Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1977 Mar;265(3):597–613. doi: 10.1113/jphysiol.1977.sp011733

Gonadotrophin secretion in the ovariectomized guinea-pig: effects of electrical stimulation of the hypothalamus and of LH-RH.

B T Donovan, M B Haar, N Parvizi
PMCID: PMC1307837  PMID: 323467

Abstract

1. Serial blood samples were collected from anaesthetized spayed guinea-pigs subjected to anterior hypothalamic stimulation or injected with luteinizing hormone-releasing hormone (LH-RH), and the effect on the secretion of follicle-stimulating hormone (FSH) and LH followed. 2. Hypothalamic stimulation enhanced LH secretion, although the response waned during the course of the 1 hr period of stimulation; the secretion of FSH was not increased. After stimulation, FSH and LH levels fell below control values. 3. The response to stimulation of the hypothalamus was greater 2 weeks after spaying than after 1 week. 4. Since repeated periods of hypothalamic stimulation induced repeated surges of LH secretion, the decline in LH secretion during stimulation was not likely to have resulted from hypothalamic damage, while the observation that the plasma concentration of FSH and LH declined below control values after brain stimulation implies the operation of inhibitory mechanisms. 5. Pre-treatment of spayed guinea-pigs with progesterone depressed the resting plasma concentration of LH but did not affect the immediate response to hypothalamic stimulation. After hypothalamic stimulation the plasma gonadotrophin levels did not fall below control values. 6. Pre-treatment with oestradiol benzoate depressed the resting plasma level of LH and slightly reduced the size of the LH surge produced by hypothalamic stimulation. However, the raised plasma LH concentration was sustained after stimulation ended. 7. The response to hypothalamic stimulation after pre-treatment with progesterone and oestradiol benzoate showed features of the reaction to each steroid given singly. 8. The I.V. injection of 0-5 microng LH-RH induced a surge of LH secretions without affecting FSH discharge. 9. Pre-treatment with progesterone did not greatly modify the response to LH-RH but after an injection of oestradiol the high level of LH produced by the releasing factor was sustained for about 2 hr. 10. Injections of LH-RH during the phase of depressed LH release after hypothalamic stimulation produced a surge of LH secretion which matched that seen in non-stimulated animals.

Full text

PDF
597

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Blatchley F. R., Donovan B. T., Ter Haar M. B. Plasma progesterone and gonadotrophin levels during the estrous cycle of the guinea pig. Biol Reprod. 1976 Aug;15(1):29–38. doi: 10.1095/biolreprod15.1.29. [DOI] [PubMed] [Google Scholar]
  2. Booth J. E., Donovan B. T. Implantation of oestrogen in the brain and the induction of ovulation in the guinea-pig. J Endocrinol. 1974 Jul;62(1):153–160. doi: 10.1677/joe.0.0620153. [DOI] [PubMed] [Google Scholar]
  3. Booth J. E., Donovan B. T. Stimulation of the hypothalamus and ovulation in the guinea-pig. J Physiol. 1974 Sep;241(2):373–388. doi: 10.1113/jphysiol.1974.sp010661. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Butler J. E., Donovan B. T. The effect of surgical isolation of the hypothalamus upon reproductive function in the female guinea-pig. J Endocrinol. 1971 Jul;50(3):507–514. doi: 10.1677/joe.0.0500507. [DOI] [PubMed] [Google Scholar]
  5. Donovan B. T., ter Haar M. B., Lockhart A. N., MacKinnon P. C., Mattock J. M., Peddie M. J. Changes in the concentration of luteinizing hormone in plasma during development in the guinea-pig. J Endocrinol. 1975 Mar;64(3):511–520. doi: 10.1677/joe.0.0640511. [DOI] [PubMed] [Google Scholar]
  6. Donovan B. T., ter Haar M. B., Lockhart A. N., Peddit M. J. Changes in the concentration of follicle-stimulating hormone in plasma during development in the guinea-pig. J Endocrinol. 1975 Mar;64(3):521–528. doi: 10.1677/joe.0.0640521. [DOI] [PubMed] [Google Scholar]
  7. Harris G. W., Manabe Y., Ruf K. B. A study of the parameters of electrical stimulation of unmyelinated fibres in the pituitary stalk. J Physiol. 1969 Jul;203(1):67–81. doi: 10.1113/jphysiol.1969.sp008850. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Quinn D. L. Comparative aspects of premature ovulation in the guinea pig and the rat following electrochemical stimulation of the hypothalamus. Endocrinology. 1974 Sep;95(3):926–929. doi: 10.1210/endo-95-3-926. [DOI] [PubMed] [Google Scholar]
  9. Quinn D. L. Hypothalamic mechanisms involved in the control of gonadotropic hormone secretion in the guinea pig: evidence of elevated brain thresholds to electrical stimulation in the medial preoptic-anterior hypothalamic region during "early" diestrus. Endocrinology. 1970 Aug;87(2):343–349. doi: 10.1210/endo-87-2-343. [DOI] [PubMed] [Google Scholar]
  10. Quinn D. L. Neural activation of gonadotropic hormone release by electrical stimulation in the hypothalamus of the guinea pig and the rat. Neuroendocrinology. 1969;4(4):254–263. doi: 10.1159/000121755. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES