Seasonal Fluctuations In Luteinizing Hormones (lh), Follicle Stimulating Hormones (FSH) And Testosterone Levels In Male African Giant Rats.

As part of the several efforts to understand the biology of the African Giant rats (AGR) (Cricetomys gambianus), seasonal changes in the gonadotropin and testosterone levels of the adult male African giant rats of about 1 – 1½ years of age in captivity were investigated during wet and dry seasons in the tropics. Male giant rats (n = 10) were kept for 12 months and blood samples were collected monthly (on 15th of each month), during the dry (November – February) and wet (March – June) seasons for Luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone assays. The hormones’ levels were evaluated to suggest the best breeding season for giant rat in South-West Nigeria. The result showed that there were significant variation (p<0.001) in LH and FSH levels in the giant rat in the wet season when compared with the dry season. However, testosterone level was significantly lower (p<0.001) in the wet season than in the dry season. The study showed that sexual activities in the male AGR might be higher in the dry season with peak activities in December in the tropics while the gonadotropins prepare the animals for sexual activities in the dry season. Further studies on the seasonal activities of gonadotropins in the female will give more insight into the sexual receptivity and performance in these animals.