Corticosterone in ovo modifies aggressive behaviors and reproductive performances through alterations of the hypothalamic-pituitary-gonadal axis in the chicken

摘要

Exposure to excess glucocorticoids during embryonic development affects offspring reproduction and suppresses the hypothalamic-pituitary-gonadal (MPG) axis in mammals. However, whether corticosterone (CURT) causes similar effects in the chicken remains unclear. In the present study, we injected low (0.2 mu g) and high (1 mu g) doses of CURT in ovo before incubation and detected changes in aggressive behavior, tonic immobility (TO, reproductive performances, and MPG axis gene expression in posthatch chickens of different ages. High dose of CURT suppressed growth rate from 3 weeks of age, increased the frequency of aggressive behaviors, which was associated with elevated plasma CURT concentration. High-dose CURT significantly (P< 0.05) down-regulated arginine vasotocin (AVT), corticotropin-releasing hormone (CRH), 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2) and gonadotropin-releasing hormone 1 (GnRH1), while significantly (P< 0.05) up-regulated gonadotropin-inhibitory hormone (GnIH) and 11 beta-HSD1 mRNA expression in the hypothalamus. Glucocorticoid receptor (GR) and 20-hydroxysteroid dehydrogenase (20-HSD) mRNA levels were not affected by CURT treatment. High-dose CURT significantly (P< 0.05) reduced egg production and egg quality, which was associated with decreased ovary and oviduct weight. Moreover, CURT exposure significantly decreased (P< 0.05) luteinizing hormone (LH) receptor and follicle-stimulating hormone (FSH) receptor mRNA abundance in theca cells of ovarian follicles 1 (Fl), F2 and F3. In addition, yolk CURT concentration was significantly higher in eggs laid by hens prenatally exposed to high-dose CURT. Our findings suggest that in ova administration of CURT programs the aggressive behaviors and reproductive functions in the chicken through alterations of HPG axis