PSX-A-24 - Late-Breaking: Testosterone production by theca cells of large preovulatory follicles is affected by growth hormone depending on the hen age and the presence of granulosa cells

Testosterone produced by theca cells may be involved in regulating of the growth and ovulation of hen preovulatory follicles (Rangel, Gutierrez, Gen Comp Endocrinol, 203:250, 2014). In the current research, we studied effects of growth hormone (GH), a known regulator of the hen ovarian function, on in vitro testosterone production by the theca layer (TL) from the two largest yellow follicles in relation to the hen age and the presence of the granulosa layer (GL). Young hens with long clutch (YLC, 32-33 week-old, >10 eggs per clutch) and old hens with short clutch (OSC, 74-76 week-old, 3-6 eggs per clutch) were used. After isolation, TL from F1 and F2 follicles (n = 8-9) was cultured for 18 h in two systems, separately or together with the corresponding GL, in the presence or absence of chicken GH (25 ng/ml). Concentrations of testosterone in the spent media were measured by ELISA. The data were analyzed by RM-ANOVA. In the case of separate TL culture, GH did not change significantly testosterone production in both follicles of YLC hens and reduced it from 338±105 to 152±52 fmol/mg tissue (P < 0.05) in F1 follicles of OSC hens. When TL was cultured in the presence of GL, GH enhanced 1.8-2.6-fold (P < 0.05) the secretion of testosterone in the case of F1 follicles and decreased it 1.8-2.5-fold (P < 0.05) in the case of F2 follicles in both young and old hens. Regardless of the treatment, follicular size or culture system, the production of testosterone in OSC hens was 2-5 times higher than in YLC hens. The results indicate that the interaction between TL and GL changes the steroidogenic response of theca cells from preovulatory follicles to GH in young and old hens. Furthermore, testosterone production is obviously increased with reproductive aging of laying hens. The study was supported by RFBR (19-016-00216).