Skip to main content
NCBI home page
Endocrinology logoLink to Endocrinology
. 2019 Feb 12;160(4):782–790. doi: 10.1210/en.2018-00985

Tamoxifen Improves Glucose Tolerance in a Delivery-, Sex-, and Strain-Dependent Manner in Mice

Alexis M Ceasrine 1,✉, Nelmari Ruiz-Otero 1, Eugene E Lin 1, David N Lumelsky 1, Erica D Boehm 1, Rejji Kuruvilla 1
PMCID: PMC6424092  PMID: 30759201

Abstract

Tamoxifen, a selective estrogen-receptor modulator, is widely used in mouse models to temporally control gene expression but is also known to affect body composition. We report that tamoxifen has significant and sustained effects on glucose tolerance, independent of effects on insulin sensitivity, in mice. IP, but not oral, tamoxifen delivery improved glucose tolerance in three inbred mouse strains. The extent and persistence of tamoxifen-induced effects were sex and strain dependent. These findings highlight the need to revise commonly used tamoxifen-based protocols for gene manipulation in mice by including longer chase periods after injection, oral delivery, and the use of tamoxifen-treated littermate controls.

Genetic mouse models have been widely used for the study of human metabolic disorders, such as diabetes. The Cre/LoxP system provides a powerful tool to manipulate gene expression in a tissue- and/or temporal-specific manner in mice. Temporal control of the Cre/LoxP system is frequently accomplished with the CreER variant, which only enters the nucleus to induce DNA recombination upon addition of the estrogen-receptor modulator tamoxifen (1, 2). Despite the widespread use of CreER/LoxP mouse lines, phenotyping the effects of tamoxifen on control animals has not been well documented. Tamoxifen has been reported to substantially reduce food intake and body weight in ovariectomized rats (3). In ovariectomized mice, tamoxifen also protects against obesity and insulin resistance induced by a high-fat diet (4). In patients with breast cancer, tamoxifen treatment has been correlated with increased risk of diabetes (5). Together, these studies suggest that tamoxifen alters glucose homeostasis, although the effects of tamoxifen on glucose tolerance and insulin secretion have been poorly defined.

Here, we report that tamoxifen administration enhances glucose tolerance in mice. IP tamoxifen administration improved glucose tolerance in three commonly used mouse strains, BALB/cJ, C57BL/6J, and 129S1/SvImJ, although the extent and persistence of enhanced glucose tolerance varied in a sex- and strain-dependent manner. In C57BL/6J mice, IP tamoxifen delivery enhanced glucose-stimulated insulin secretion (GSIS) in males, but not females. In addition, acute tamoxifen treatment enhanced basal insulin secretion in isolated islets from male C57BL/6J mice. Tamoxifen administration had no effect on insulin sensitivity. Intriguingly, oral administration of tamoxifen through diet did not affect glucose tolerance. Together, these results highlight the need for caution in interpreting results of metabolic changes when using IP tamoxifen delivery for temporal control of gene expression in mice, and suggest revised measures, such as extended chase periods after injection, oral delivery, and comparison with tamoxifen-treated littermate controls.

Materials and Methods

Animals

All procedures relating to animal care and treatment conformed to The Johns Hopkins University Animal Care and Use Committee and National Institutes of Health guidelines. Animals were group housed under a standard 12:12 light-dark cycle. Animals of both sexes were used for all analyses, and the sex of the animals is clearly noted throughout the report. BALB/cJ (stock no. 000651), C57BL/6J (stock no. 000664), and 129S1/SvImJ (stock no. 002448) mice were obtained from Jackson Laboratories.

Tamoxifen administration

IP injection

At 6 weeks of age, mice were injected IP with 100 mg/kg tamoxifen in corn oil, or corn oil alone, daily for 5 days. Metabolic assays were performed 1 to 3 weeks after the final injection.

Oral administration

Beginning at 5 weeks of age, mice were switched from standard chow to either control diet (TD.07570; Envigo) or tamoxifen diet (TD.130856; Envigo) for 10 days with a 2-day break on standard chow after the fifth day. Because oral tamoxifen administration has been reported to reduce food intake and body weight (6), mice were given 6 days to recover on standard chow before glucose tolerance testing.

Glucose tolerance and in vivo insulin secretion

Mice were individually housed and fasted overnight (16 hours) before glucose administration. For IP glucose tolerance and insulin secretion tests, mice were administered 2 g/kg glucose and 3 g/kg glucose, respectively. For oral glucose tolerance tests and insulin secretion tests, mice were administered 3 g/kg glucose by gavage feeding needle. Blood glucose levels were measured with a OneTouch Ultra 2 glucometer (Lifescan), and plasma insulin levels were measured with an Ultrasensitive Insulin ELISA (Crystal Chem) (7). The area under the curve was determined for glucose tolerance for each animal, using GraphPad Prism, version 8.

Insulin tolerance

Mice were individually housed with food overnight before 0.75U/kg IP insulin injection (Novolin-R; Novo Nordisk). Blood glucose levels were measured with a OneTouch Ultra 2 glucometer.

Mouse islet isolations and in vitro insulin secretion

Islets were isolated from male C57BL/6J mice as previously described (8). Briefly, islets were isolated by collagenase distension through the bile duct (Collagenase P, 0.375 to 0.4 mg/mL in Hanks balanced salt solution) and digestion at 37°C. Digested pancreata were washed with Hanks balanced salt solution plus 0.1% BSA and subjected to discontinuous density gradient using Histopaque (6:5 Histopaque 1119 to Histopaque 1077; Sigma). The islet layer (found at the interface) was collected, and islets were handpicked under an inverted microscope and cultured overnight in RPMI 1640 (5% FBS, 5 U/L penicillin-streptomycin). Islets were then handpicked to be size matched, and 5 to 10 islets per mouse were washed and preincubated for 30 minutes in Krebs-Ringer HEPES buffer containing 2.8 mM glucose. Tamoxifen (10 µM) or vehicle (dimethyl sulfoxide) was added and islets were incubated for 30 minutes. Supernatant was sampled and islets were then stimulated with 16.7 mM glucose for another 30 minutes. Supernatant fractions were removed and islets lysed in acid-ethanol overnight and subsequently neutralized in Tris buffer (0.885 M). Cellular and supernatant fractions were subjected to insulin ELISA (7).

Results

IP tamoxifen injections improved glucose tolerance in mice

To assess the effects of tamoxifen on glucose metabolism in mice, we used a common paradigm for tamoxifen-inducible gene inactivation in CreER/LoxP mouse models via IP administration of tamoxifen (100 mg/kg body weight in corn oil) for 5 consecutive days (9). Control animals were administered equivalent volumes of corn oil alone. We assessed glucose tolerance, insulin tolerance, and GSIS in vivo in three inbred mouse strains: BALB/cJ, C57BL/6J, and 129S1/SvImJ. Body weights were measured weekly and were unaffected in both sexes of all strains tested after tamoxifen injection.

After tamoxifen injections, we performed glucose tolerance tests on male and female mice from all three strains 1 week after the final administration. Tamoxifen injections significantly improved glucose tolerance in male and female BALB/cJ and C57BL/6J mice (Fig. 1A–1F), and in female, but not male, 129S1/SvImJ mice (Fig. 1G–1I). Of note, tamoxifen-injected male BALB/cJ mice also had significantly lower fasted blood glucose levels compared with controls (Fig. 1A). Together, these results suggest that IP tamoxifen administration enhances glucose tolerance in mice.

Figure 1.

Figure 1.

Open in a new tab

IP tamoxifen injections improved glucose tolerance in mice. Data are presented as mean ± SEM unless otherwise indicated. (A) Male and (B) female BALB/cJ mice (n = 5 to 7 mice per sex per condition) had significantly improved glucose tolerance after IP tamoxifen (TMX) administration. (C) Area under the curve for BALB/cJ mice glucose tolerance. (D) Male and (E) female C57BL/6J mice (n = 6 to 9 mice per sex per condition) had significantly improved glucose tolerance after IP TMX administration. (F) Area under the curve for glucose tolerance in C57BL/6J mice glucose tolerance. (G) Glucose tolerance in male 129S1/SvImJ mice (n = 7 male 129S mice per condition) did not change in response to IP TMX administration. (H) TMX-injected female 129S1/SvImJ mice (n = 6 female mice per condition) had significantly improved glucose tolerance. (I) Area under the curve for 129S1/SvImJ mice glucose tolerance. Differences determined by t tests. *P < 0.05; **P < 0.01; ***P < 0.001. Veh, vehicle.

Persistence of improved glucose tolerance in tamoxifen-injected mice was sex and strain dependent

To determine if the effects of tamoxifen injection on glucose tolerance persisted, we extended the recovery period to 21 days after the final tamoxifen injection. Three weeks after tamoxifen delivery, male and female BALB/cJ mice and male C57BL/6J mice still had improved glucose tolerance (Fig. 2A–2D and 2F), albeit to a lower extent than the tamoxifen-induced effects observed 1 week after injections (Fig. 1A–1F). However, in female C57BL/6J mice, tamoxifen-induced enhancement of glucose tolerance was corrected by 3 weeks (Fig. 2E and 2F). Female 129S1/SvImJ mice still showed a modest improvement in glucose tolerance 3 weeks after injections (Fig. 2H and 2I). Glucose tolerance in male 129S1/SvImJ mice was still unaffected 3 weeks after injection (Fig. 2G and 2I). Together, these results suggest that the effects of IP tamoxifen delivery on improving glucose tolerance persist in a sex- and strain-dependent manner at 3 weeks after injections, with male mice tending to exhibit more long-lasting effects. Overall, the effects of tamoxifen on enhancing glucose tolerance 3 weeks postinjection were modest compared with 1-week postinjection, suggesting that extended recovery periods after tamoxifen delivery in CreER mouse lines may be sufficient to avoid tamoxifen-induced effects on glucose tolerance.

Figure 2.

Figure 2.

Open in a new tab

Persistence of improved glucose tolerance in tamoxifen-injected mice was sex and strain dependent. Data are presented as mean ± SEM unless otherwise indicated. (A) Male and (B) female BALB/cJ mice (n = 5 to 8 mice per sex per condition) retained significantly improved glucose tolerance 3 weeks after IP tamoxifen (TMX) administration. (C) Area under the curve for BALB/cJ glucose tolerance. (D) Male, but not (E) female, C57BL/6J mice (n = 6 to 7 mice per sex per condition) retained significantly improved glucose tolerance 3 weeks after IP TMX administration. (F) Area under the curve for C57BL/6J mice glucose tolerance. (G) Glucose tolerance did not change in male 129S1/SvImJ mice (n = 4 per condition) in response to IP TMX administration. (H) Glucose tolerance in TMX-injected female 129S1/SvImJ mice (n = 4 per condition) was modestly improved 3 weeks after final injection. (I) Area under the curve remained significantly lower for female 129S1/SvImJ mice. Differences determined by t tests. *P < 0.05; **P < 0.01. Veh, vehicle.

IP tamoxifen administration enhanced insulin secretion in male C57BL/6J mice, but insulin sensitivity was unaffected

Improved glucose tolerance can be caused by a variety of factors, including enhanced insulin secretion from pancreatic islets or improved insulin sensitivity in peripheral tissues. Estrogen-receptor signaling promotes GSIS in isolated islets, and tamoxifen can bind to pancreatic estrogen receptors (10, 11). Furthermore, tamoxifen-induced Cre-mediated recombination persists up to 4 weeks after tamoxifen injection in pancreatic islets (12). Therefore, we asked if tamoxifen injection improves glucose tolerance by influencing insulin secretion.We assessed GSIS in vivo in male and female C57BL/6J mice, the most commonly used inbred mouse strain (13), 1 week after final IP tamoxifen injection. Tamoxifen injections enhanced GSIS in male, but not female, C57BL/6J mice (Fig. 3A and 3B), suggesting sex-specific effects of tamoxifen on insulin secretion. Insulin tolerance tests revealed that tamoxifen injections had no effect on insulin sensitivity in male and female C57BL/6J mice (Fig. 3C and 3D). To assess if tamoxifen directly acts on β cells to influence insulin secretion, we isolated islets from male C57BL/6J mice and stimulated them with 10 µM tamoxifen before assessing insulin secretion. At low-glucose concentration (2.8 mM), tamoxifen treatment significantly increased insulin secretion (Fig. 3E). However, tamoxifen treatment did not augment insulin secretion in response to high-glucose concentration (16.7 mM; data not shown). Together, these results suggest that although tamoxifen can induce insulin secretion, tamoxifen-induced improvement of glucose tolerance in male C57BL/6J mice arises from islet-specific and islet-extrinsic factors. Furthermore, enhanced insulin sensitivity is not a contributing factor to the tamoxifen-induced improved glucose tolerance.

Figure 3.

Figure 3.

Open in a new tab

IP tamoxifen (TMX) administration enhanced insulin secretion in male C57BL/6J mice, but insulin sensitivity was unaffected. Data are presented as mean ± SEM unless otherwise indicated. Differences were determined by t tests. (A) GSIS was improved after IP TMX administration in male C57BL/6J mice (n = 5 to 11 mice per condition). (B) GSIS was unchanged by IP TMX administration in female C57BL/6J mice (n = 5 to 8 mice per condition). Insulin sensitivity was unaffected by IP TMX administration in (C) male and (D) female C57BL/6J mice (n = 5 to 6 mice per condition per sex). (E) TMX stimulation significantly increased islet insulin secretion in low-glucose (2.8 mM) conditions (n = 6 vehicle-treated islet cultures and n = 5 TMX-treated islet cultures from six mice). One-sample t test; *P < 0.05. (F) Male TMX-injected C57BL/6J mice (n = 3 to 4 mice per condition) had improved glucose tolerance in response to an oral glucose challenge 1 week after the final TMX injection. (G) Area under the curve for oral glucose tolerance was significantly lower in TMX-injected male C57BL/6J mice. (H) Oral GSIS was improved after IP TMX administration in male C57BL/6J mice (n = 3 to 5 mice per condition). *P < 0.05. Veh, vehicle.

Release of intestinal incretin hormones modulates GSIS in vivo. Incretin release is stimulated by oral, but not IP, glucose delivery in mice (14). We assessed the effects of tamoxifen on glucose tolerance and insulin secretion in vivo in response to an oral glucose challenge via gavage. Male tamoxifen-injected C57BL/6J mice had enhanced glucose tolerance and insulin secretion in response to oral glucose compared with controls, and the tamoxifen effects were similar in magnitude to that seen with IP glucose delivery (Fig. 3F–3H). These results suggest that effects of tamoxifen on glucose tolerance are likely independent of incretin signaling.

Oral tamoxifen delivery did not affect glucose tolerance

Recent studies have described the use of tamoxifen-supplemented chow as an effective and noninvasive means for spatiotemporal gene activation in CreER mouse lines (15, 16). Furthermore, plasma tamoxifen levels are lower after oral tamoxifen delivery vs injection (17). Thus, we asked if oral tamoxifen delivery would also affect glucose tolerance in mice.

We fed mice commercially available tamoxifen-supplemented or control diets for 10 days with a 2-daybreak after the fifth day. This paradigm was based on the assumption that mice consume an average of 3 to 4 g of food daily and weigh 20 to 25 g, corresponding to ∼40 mg of tamoxifen per kilogram of body weight per day (18). Approximate tamoxifen consumption was estimated by weighing tamoxifen-supplemented chow before and after the treatment period and calculating the milligrams of tamoxifen consumed per animal (based on 250 mg tamoxifen per kilogram of food).

These analyses suggested that comparable amounts of tamoxifen were delivered between IP injection and diet delivery [∼500 mg/kg total from injection vs 440 ± 77 mg/kg for males and 432 ± 73 mg/kg for females from diet (values are mean ± SD for 10 males and 11 females from all three strains)]. Interestingly, glucose tolerance was unaffected by oral tamoxifen administration in males and females in all three mouse strains tested 6 days after treatment (Fig. 4A–4I). These results suggest that the mode of tamoxifen administration significantly influences its effects on glycemic control.

Figure 4.

Figure 4.

Open in a new tab

Oral tamoxifen (TMX) administration did not affect glucose tolerance. Data are presented as mean ± SEM unless otherwise indicated. Glucose tolerance did not change in (A) male and (B) female BALB/cJ mice (n = 4 to 5 mice per sex per condition) in response to TMX diet. (C) Area under the curve for BALB/cJ mice glucose tolerance. Glucose tolerance did not change in (D) male or (E) female C57BL/6J mice (n = 4 to 5 mice per sex per condition) in response to TMX diet. (F) Area under the curve for C57BL/6J mice glucose tolerance. Glucose tolerance did not change in (G) male or (H) female 129S1/SvImJ mice (n = 3 to 5 mice per sex per condition) in response to TMX diet. (I) Area under the curve for 129S1/SvImJ mice glucose tolerance. Veh, vehicle.

Discussion

Here, we report that IP, but not oral, tamoxifen administration to three common inbred mouse strains induced a significant and often sustained improvement of glucose tolerance without affecting insulin sensitivity. Interestingly, male, but not female, C57BL/6J mice had increased GSIS in vivo. In isolated islets from male C57BL/6J mice, acute tamoxifen stimulation increased insulin secretion under basal conditions (2.8 mM glucose) but did not augment insulin secretion in response to high (16.7 mM) glucose concentration. These results suggest that although tamoxifen can promote islet insulin secretion, the enhanced GSIS in vivo is likely due to a combination of islet-dependent and islet-independent effects of tamoxifen.

Estrogens and estrogen-receptor signaling play important roles in β-cell function as well as protection of β-cell mass (11, 19–23). β cells express the estrogen receptors ERα, ERβ, and GPER, and all three have been implicated in aspects of β-cell biology. Specifically, ERα primarily promotes β-cell survival as well as glucose-stimulated insulin biosynthesis (11, 19–21). ERβ promotes insulin secretion via membrane depolarization, and GPER promotes β-cell survival and insulin secretion (19, 22). The actions of these estrogen receptors, combined with our results, suggest tamoxifen may act as an agonist for β-cell estrogen receptor(s) to increase insulin secretion in low-glucose conditions. This mechanism is consistent with previous studies demonstrating the role of estrogen signaling in depolarizing β-cell membranes to induce insulin secretion in low, but not high, glucose conditions in a mouse β-cell line (MIN6) and human islets (23). Our observations that GSIS in vivo was increased after IP tamoxifen delivery suggests that although tamoxifen can increase basal insulin secretion in isolated islets, islet-extrinsic factors may contribute to tamoxifen effects on glucose-stimulated insulin secretion and glucose tolerance in vivo. Our results suggest that incretin release, which is known to augment GSIS in vivo, is not a contributing factor to the effects of tamoxifen; we found similar effects of tamoxifen on improving glucose tolerance and insulin secretion with IP and oral glucose delivery. In addition to the role of estrogens in promoting β-cell insulin secretion, estrogen signaling promotes neural-dependent insulin secretion in male mice (24), and neuronal signaling might underlie the tamoxifen-induced increase in GSIS in male C57BL/6J mice. We found that tamoxifen administration had no effect on insulin sensitivity. However, glucose-clamp experiments are required to more precisely dissect the effects of tamoxifen on insulin sensitivity.

Enhanced glucose tolerance in female C57BL/6J mice upon tamoxifen treatment was not coupled with increased in vivo GSIS, as was the case in males. Enhanced glucose tolerance in female C57BL/6J mice could arise from changes in insulin-independent glucose uptake mechanisms. Results of previous studies suggest insulin-independent glucose uptake is prominent during hyperglycemia in tissues such as skeletal muscle (25). Notably, estrogen-receptor signaling in skeletal muscle promotes membrane localization of the glucose transporter GLUT4 in an insulin-independent manner (26). These findings, together with our observations, suggest that tamoxifen may regulate glucose tolerance in female C57BL/6J mice by promoting insulin-independent glucose uptake.

Studies have reported on sex and stain differences in glucose metabolism in mice (27). Our results indicate that the magnitude and persistence of tamoxifen-induced enhancement of glucose tolerance were sex and strain dependent. The persistence of tamoxifen in the body has reported to be age dependent, with older animals being unable to effectively clear tamoxifen (28). We used young animals (2 months old), and tamoxifen-injected animals were always compared with age-matched, vehicle-injected controls. Therefore, age is unlikely to be a factor in the observed sex- and strain-dependent effects of tamoxifen on glucose tolerance. Tamoxifen persists differentially in different tissues. For example, tamoxifen has acute effects in the brain (28) and more long-lasting effects in pancreatic islets, with tamoxifen-induced Cre activity persisting for as long as 4 weeks after IP injections (12). Therefore, tamoxifen may act differently in distinct tissues in a sex- and strain-specific manner to influence glucose tolerance. C57BL/6J mice carry a genomic mutation resulting in diminished levels of the mitochondrial pump nicotinamide nucleotide transhydrogenase (Nnt), and NNT levels are thought to positively correlate with insulin secretion (29, 30). We found that BALB/cJ and female 129S1/SvImJ mice, which have not been reported to carry the NNT mutation, have improved glucose tolerance upon tamoxifen treatment, similar to C57BL/6J mice that carry the mutation. Therefore, the NNT mutation in C57BL/6J mice is unlikely to be a critical factor in the effects of tamoxifen on glucose tolerance and insulin secretion. However, a rigorous comparison of C57BL/6J and C57BL/6N mice, which do not carry the Nnt mutation (30), would shed light on this possibility.

Intriguingly, oral administration of tamoxifen did not affect glucose tolerance. Compared with injection-based tamoxifen administration, oral tamoxifen delivery results in lower plasma tamoxifen levels but higher circulating levels of tamoxifen metabolites, such as 4-hydroxytamoxifen (17). Improved glucose tolerance with tamoxifen injection might be due to the higher and persistent circulating tamoxifen levels compared with oral administration. This suggests that the effects of tamoxifen may be dose dependent; low doses of tamoxifen, even delivered IP, may not affect glucose tolerance. However, in the case of CreER lines, such low doses may not be effective for inducing gene recombination (31). In addition, this suggests that enhanced glucose tolerance after IP tamoxifen administration is likely due to tamoxifen itself, not one of its metabolites. If this is the case, then injection of 4-hydroxytamoxifen, a tamoxifen metabolite that is a potent activator of CreER, may bypass the tamoxifen-dependent effects, similarly to oral tamoxifen administration (2). Our findings highlight the need to revise commonly used tamoxifen-based protocols for gene manipulation in mice, including considering oral delivery, allowing longer chase periods after injection, and the use of tamoxifen-treated littermate controls.

Acknowledgments

Financial Support: This work was supported by the National Institutes of Health (NIH; Grant DK108267 to R.K.) and an NIH National Research Service Award (Postdoctoral Fellowship F32DK116482 to E.E.L.). A.M.C., N.R.-O., and E.D.B. are supported by NIH Training Grant T32GM007231 awarded to the Johns Hopkins University Cell, Molecular, Developmental Biology, and Biophysics program.

Author Contributions: A.M.C. designed and performed experiments, analyzed data, wrote the manuscript, and is the guarantor of this work. N.R.-O. performed experiments, analyzed data, and reviewed and edited the manuscript. E.E.L. performed experiments and reviewed and edited the manuscript. D.N.L. and E.D.B. performed experiments. R.K. designed experiments and reviewed and edited the manuscript.

Disclosure Summary: The authors have nothing to disclose.

Glossary

Abbreviations:

GSIS

glucose-stimulated insulin secretion

NNT

nicotinamide nucleotide transhydrogenase

References

  • 1. Metzger D, Chambon P. Site- and time-specific gene targeting in the mouse. Methods. 2001;24(1):71–80. [DOI] [PubMed] [Google Scholar]
  • 2. Feil R, Wagner J, Metzger D, Chambon P. Regulation of Cre recombinase activity by mutated estrogen receptor ligand-binding domains. Biochem Biophys Res Commun. 1997;237(3):752–757. [DOI] [PubMed] [Google Scholar]
  • 3. Wade GN, Heller HW. Tamoxifen mimics the effects of estradiol on food intake, body weight, and body composition in rats. Am J Physiol. 1993;264(6 Pt 2):R1219–R1223. [DOI] [PubMed] [Google Scholar]
  • 4. Guillaume M, Handgraaf S, Fabre A, Raymond-Letron I, Riant E, Montagner A, Vinel A, Buscato M, Smirnova N, Fontaine C, Guillou H, Arnal JF, Gourdy P. Selective activation of estrogen receptor α activation function-1 is sufficient to prevent obesity, steatosis, and insulin resistance in mouse. Am J Pathol. 2017;187(6):1273–1287. [DOI] [PubMed] [Google Scholar]
  • 5. Lipscombe LL, Fischer HD, Yun L, Gruneir A, Austin P, Paszat L, Anderson GM, Rochon PA. Association between tamoxifen treatment and diabetes: a population-based study. Cancer. 2012;118(10):2615–2622. [DOI] [PubMed] [Google Scholar]
  • 6. Chiang PM, Ling J, Jeong YH, Price DL, Aja SM, Wong PC. Deletion of TDP-43 down-regulates Tbc1d1, a gene linked to obesity, and alters body fat metabolism. Proc Natl Acad Sci USA. 2010;107(37):16320–16324. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7. RRID:AB_2783626.
  • 8. Wollheim CB, Meda P, Halban PA. Isolation of pancreatic islets and primary culture of the intact microorgans or of dispersed islet cells. Methods Enzymol. 1990;192:188–223. [DOI] [PubMed] [Google Scholar]
  • 9. Jahn HM, Kasakow CV, Helfer A, Michely J, Verkhratsky A, Maurer HH, Scheller A, Kirchhoff F. Refined protocols of tamoxifen injection for inducible DNA recombination in mouse astroglia. Sci Rep. 2018;8(1):5913. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 10. Zhou Z, Ribas V, Rajbhandari P, Drew BG, Moore TM, Fluitt AH, Reddish BR, Whitney KA, Georgia S, Vergnes L, Reue K, Liesa M, Shirihai O, van der Bliek AM, Chi NW, Mahata SK, Tiano JP, Hewitt SC, Tontonoz P, Korach KS, Mauvais-Jarvis F, Hevener AL. Estrogen receptor α protects pancreatic β-cells from apoptosis by preserving mitochondrial function and suppressing endoplasmic reticulum stress. J Biol Chem. 2018;293(13):4735–4751. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11. Le May C, Chu K, Hu M, Ortega CS, Simpson ER, Korach KS, Tsai MJ, Mauvais-Jarvis F. Estrogens protect pancreatic beta-cells from apoptosis and prevent insulin-deficient diabetes mellitus in mice. Proc Natl Acad Sci USA. 2006;103(24):9232–9237. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12. Reinert RB, Kantz J, Misfeldt AA, Poffenberger G, Gannon M, Brissova M, Powers AC. Tamoxifen-induced Cre-loxP recombination is prolonged in pancreatic islets of adult mice. PLoS One. 2012;7(3):e33529. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 13. Battey J, Jordan E, Cox D, Dove W. An action plan for mouse genomics. Nat Genet. 1999;21(1):73–75. [DOI] [PubMed] [Google Scholar]
  • 14. Andrikopoulos S, Blair AR, Deluca N, Fam BC, Proietto J. Evaluating the glucose tolerance test in mice. Am J Physiol Endocrinol Metab. 2008;295(6):E1323–E1332. [DOI] [PubMed] [Google Scholar]
  • 15. Kiermayer C, Conrad M, Schneider M, Schmidt J, Brielmeier M. Optimization of spatiotemporal gene inactivation in mouse heart by oral application of tamoxifen citrate. Genesis. 2007;45(1):11–16. [DOI] [PubMed] [Google Scholar]
  • 16. Andersson KB, Winer LH, Mørk HK, Molkentin JD, Jaisser F. Tamoxifen administration routes and dosage for inducible Cre-mediated gene disruption in mouse hearts. Transgenic Res. 2010;19(4):715–725. [DOI] [PubMed] [Google Scholar]
  • 17. Reid JM, Goetz MP, Buhrow SA, Walden C, Safgren SL, Kuffel MJ, Reinicke KE, Suman V, Haluska P, Hou X, Ames MM. Pharmacokinetics of endoxifen and tamoxifen in female mice: implications for comparative in vivo activity studies. Cancer Chemother Pharmacol. 2014;74(6):1271–1278. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18. Welle S, Burgess K, Thornton CA, Tawil R. Relation between extent of myostatin depletion and muscle growth in mature mice. Am J Physiol Endocrinol Metab. 2009;297(4):E935–E940. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19. Liu S, Le May C, Wong WP, Ward RD, Clegg DJ, Marcelli M, Korach KS, Mauvais-Jarvis F. Importance of extranuclear estrogen receptor-alpha and membrane G protein-coupled estrogen receptor in pancreatic islet survival. Diabetes. 2009;58(10):2292–2302. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20. Wong WP, Tiano JP, Liu S, Hewitt SC, Le May C, Dalle S, Katzenellenbogen JA, Katzenellenbogen BS, Korach KS, Mauvais-Jarvis F. Extranuclear estrogen receptor-α stimulates NeuroD1 binding to the insulin promoter and favors insulin synthesis. Proc Natl Acad Sci USA. 2010;107(29):13057–13062. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21. Liu S, Mauvais-Jarvis F. Rapid, nongenomic estrogen actions protect pancreatic islet survival. Islets. 2009;1(3):273–275. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22. Soriano S, Ropero AB, Alonso-Magdalena P, Ripoll C, Quesada I, Gassner B, Kuhn M, Gustafsson JA, Nadal A. Rapid regulation of K(ATP) channel activity by 17beta-estradiol in pancreatic beta-cells involves the estrogen receptor beta and the atrial natriuretic peptide receptor. Mol Endocrinol. 2009;23(12):1973–1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23. Al-Majed HT, Squires PE, Persaud SJ, Huang GC, Amiel S, Whitehouse BJ, Jones PM. Effect of 17beta-estradiol on insulin secretion and cytosolic calcium in Min6 mouse insulinoma cells and human islets of Langerhans. Pancreas. 2005;30(4):307–313. [DOI] [PubMed] [Google Scholar]
  • 24. Allard C, Morford JJ, Xu B, Salwen B, Xu W, Desmoulins L, Zsombok A, Kim JK, Levin ER, Mauvais-Jarvis F. Loss of nuclear and membrane estrogen receptor-α differentially impairs insulin secretion and action in male and female mice [published online ahead of print 10 October 2018] Diabetes. doi: 10.2337/db18-0293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 25. Baron AD, Brechtel G, Wallace P, Edelman SV. Rates and tissue sites of non-insulin- and insulin-mediated glucose uptake in humans. Am J Physiol. 1988;255(6 Pt 1):E769–E774. [DOI] [PubMed] [Google Scholar]
  • 26. Deng JY, Hsieh PS, Huang JP, Lu LS, Hung LM. Activation of estrogen receptor is crucial for resveratrol-stimulating muscular glucose uptake via both insulin-dependent and -independent pathways. Diabetes. 2008;57(7):1814–1823. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 27. Berglund ED, Li CY, Poffenberger G, Ayala JE, Fueger PT, Willis SE, Jewell MM, Powers AC, Wasserman DH. Glucose metabolism in vivo in four commonly used inbred mouse strains. Diabetes. 2008;57(7):1790–1799. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 28. Valny M, Honsa P, Kirdajova D, Kamenik Z, Anderova M. Tamoxifen in the mouse brain: implications for fate-mapping studies using the tamoxifen-inducible Cre-loxP system. Front Cell Neurosci. 2016;10:243. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29. Toye AA, Lippiat JD, Proks P, Shimomura K, Bentley L, Hugill A, Mijat V, Goldsworthy M, Moir L, Haynes A, Quarterman J, Freeman HC, Ashcroft FM, Cox RD. A genetic and physiological study of impaired glucose homeostasis control in C57BL/6J mice. Diabetologia. 2005;48(4):675–686. [DOI] [PubMed] [Google Scholar]
  • 30. Wong N, Blair AR, Morahan G, Andrikopoulos S. The deletion variant of nicotinamide nucleotide transhydrogenase (Nnt) does not affect insulin secretion or glucose tolerance. Endocrinology. 2010;151(1):96–102. [DOI] [PubMed] [Google Scholar]
  • 31. Zhang H, Fujitani Y, Wright CV, Gannon M. Efficient recombination in pancreatic islets by a tamoxifen-inducible Cre-recombinase. Genesis. 2005;42(3):210–217. [DOI] [PubMed] [Google Scholar]

Articles from Endocrinology are provided here courtesy of The Endocrine Society

RESOURCES