Fig. 1.
SSTCre:γ2f/fmice are resilient to chronic stress-induced downregulation of SST. A–E) Quantification of SST- and PV-IP interneurons in NS and UCMS-exposed SSTCre:γ2f/f and γ2f/f mice. A) Representative micrographs of PLC sections immuno-stained for SST (red), PV (cyan) and NeuN (green). Scale bar, 150 μm. B-E) Summary statistics of interneuron densities normalized to NeuN-positive neurons. B) UCMS reduced the density of SST-IP cells in the PLC of γ2f/f mice (F1, 22 = 7.435, p = 0.012, ANOVA, p = 0.01, Fisher's test) but not SSTCre:γ2f/f mice (p = 0.33). The density of SST-IP cells was greater in UCMS SSTCre:γ2f/f than UCMS γ2f/f mice (p = 0.004). C) In the ILC, UCMS reduced the density of SST-IP cells in γ2f/f (F1,20 = 9.923, p = 0.005, ANOVA; p = 0.004, Fisher's test) but not SSTCre:γ2f/f mice (p = 0.24). The density of SST-IP cells was greater in UCMS SSTCre:γ2f/f than UCMS γ2f/f mice (p = 0.002). D,E) The density of PV-IP cells in the PLC (D) and ILC (E) was unaffected by UCMS and genotype. F) In the PLC of males, UCMS reduced the density of SST-IP cells in γ2f/f mice (F1,13 = 7.03, p = 0.020, ANOVA; p = 0.028, Fisher's test) but not SSTCre:γ2f/f mice (p = 0.24). G) Similarly, in the ILC, UCMS reduced the density of SST-IP cells in γ2f/f (F1,11 = 5.44, p = 0.040, ANOVA; p = 0.038, Fisher's LSD) but not SSTCre:γ2f/f mice (p = 0.35). The density of SST-IP cells trended higher in UCMS SSTCre:γ2f/f vs UCMS γ2f/f mice (p = 0.096). H,I) The density of PV-IP cells in the PLC (H) and ILC (I) of males was unaffected by UCMS and genotype. J,K) The density of SST-IP cells of female mice was increased in SSTCre:γ2f/f vs. γ2f/f mice in both PLC (J) (F1,5 = 6.85, p = 0.047) and ILC (K) (F1,5 = 65.44, p = 0.0005) with a trend for increased density of SST-IP cells in UCMS SSTCre:γ2f/f vs. UCMS γ2f/f mice (p = 0.06). In the ILC, the density of SST-IP cells was reduced by UCMS (F1,5 = 13.86, p = 0.014) and increased in NS SSTCre:γ2f/f vs. NS γ2f/f mice (p = 0.006) and increased in UCMS SSTCre:γ2f/f vs. UCMS γ2f/f mice (p = 0.0009). UCMS selectively reduced the density of SST-IP cells in γ2f/f (p = 0.018) but not SSTCre:γ2f/f mice. L,M) The density of PV-IP cells in the PLC (L) and ILC (M) was unaffected by stress (PLC: F1,5 = 4.21, p = 0.10; ILC: F1,5 = 0.0042, p = 0.95) but increased in PLC of SSTCre:γ2f/f vs. γ2f/f mice. No such genotype effect was evident in the ILC (F1,5 = 0.77, p = 0.42). The density of PV-IP cells in the PLC was increased in SSTCre:γ2f/f vs. γ2f/f mice independent of stress (F1,5 = 6.67, p = 0.049). N) STPT of NS and UCMS SSTCre:γ2f/+:Ai9 mice, with micrographs illustrating tdT-positive cells from the PLC, ILC and ventral hippocampus (HIPP). Square insets in the first column of images highlight areas enlarged in the second and third column. Dotted lines demarcate the anterior cingulate cortex (ACAd) from the PLC and the postpiriform transition area from the hippocampus (HIPP), respectively. O) Summary data comparing densities of tdT-positive cells in NS vs. UCMS treated SSTCre:γ2f/+:Ai9 mice. Scale bar, 200 μm. Data represent 2-way ANOVA and Fisher's test. Graphs represent means ± SE. *p < 0.05, **p < 0.01, ***p < 0.001. For a complete list of ANOVAs and posthoc tests see Supplement 2. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)