Fig. 5: Chronic social isolation enhances oxytocin receptor expression and sensory neuron responses in the vomeronasal organ.

A The relative quantitative expression of Oxtr transcripts is increased in the VNO of WT isol (burgundy; n = 7, 3 males and 4 females) compared to WT group (gray; n = 6, 3 males and 3 females), with no significant changes in Gapdh transcripts or in MOE or OB tissues. Both transcripts are normalized to Actb housekeeping transcript levels. B Subcellular quantification of fluorescent in situ hybridization puncta in WT group (n = 4, 2 males and 2 females) and WT isol (burgundy, n = 4, 1 male and 3 females), along with representative pictures (C) confirmed an enrichment of Oxtr transcripts (green; DAPI counterstaining, blue) in the VNE (arrowheads) of WT isol (right) compared to WT group males (left), the difference was not statistically significant. Calcium imaging showed that a higher percentage of VSN cells from WT isol (burgundy; n = 4 males) responded to urine (D), but not to oxytocin (1 µM; E), compared to WT group (gray; n = 5 males). In contrast, KO group (turquoise; n = 5 males) displayed a decreased percentage of cells responding to both stimuli, which was restored by chronic social isolation (KO isol; purple; n = 5 males). F Representative calcium imaging traces showed VSN responses to urine and oxytocin stimulations. Data are presented as mean ± sd. Statistical significance was determined using Kruskal-Wallis tests (A), a two-tailed Student’s t-test (B) or Fisher’s exact test (D–E) between groups. *: p value < 0.05, **: p < 0.01, ***: p < 0.001, ****: p < 0.0001. MOE, main olfactory epithelium; NSE, non-sensory tissue; OB, olfactory bulb; KO group, Shank3 KO raised in groups; KO isol, Shank3 KO exposed to 4-week chronic social isolation; Oxtr, oxytocin receptor; VNE, vomeronasal sensory epithelium; VNO, vomeronasal organ; VSN, vomeronasal sensory neurons; WT group, WT raised in groups; WT isol, WT exposed to 4-week chronic social isolation.