Melatonin prevents testosterone-induced suppression of immune parameters and splenocyte proliferation in Indian tropical jungle bush quail, Perdicula asiatica.

During reproductive inactive phase (winter months) peripheral high melatonin and low testosterone was noted in male Indian tropical bird, Perdicula asiatica. During this phase exogenous testosterone (1 mg/100 g Bwt./day) suppressed the immune parameters [spleen weight, total leukocyte count (TLC), lymphocyte count (LC), and percent stimulation ratio (% SR)] and depleted splenic cellular density, while melatonin (25 microg/100g Bwt./day) restored the immune parameters and splenic cellular density to the level of control birds. In vitro suppression of splenocyte proliferation by testosterone (3 ng/ml) was also reversed by melatonin (500 pg/ml) supplementation. Therefore, high melatonin in circulation during the reproductive inactive phase acts as immunostimulator and is of high adaptive significance to this bird for survival during the adverse conditions of season and reproductive phase.