The positive relationship between androgens and hematocrit levels in the Japanese quail (Coturnix japonica).

Studies have confirmed the involvement of androgens in bird erythropoiesis, suggesting its potential function as a mediator thereof. However, little is known on whether anti-androgenic treatment reduces erythropoiesis and whether changes in endogenous androgen levels are reflected in red blood cell (RBC) indices in birds. Clarifying such issues would highlight the importance of androgens in mediating avian erythropoiesis and bring attention to the effects of endocrine-disrupting chemicals with anti-androgenic activity on their ecology. The present study focused on hematocrit levels among the RBC indices, as well as the relationship between androgens and hematocrit levels in the Japanese quail (Coturnix japonica). In experiment 1, daily injections (i.m.) of testosterone propionate administered to immature quails for a week dose-dependently increased their hematocrit levels. In experiment 2, daily injections (i.m.) of flutamide, a general antagonist of the androgen receptor (AR), administered to adult male quails for a week dose-dependently decreased their hematocrit levels. In experiment 3, weekly blood collection from male quails through the immature to mature stages revealed that changes in endogenous testosterone concentrations were correlated with changes in hematocrit levels along with sexual maturation. The aforementioned results suggested that androgen stimulates erythropoiesis via the ARs and further highlighted the biological importance of androgens on erythropoiesis in quails. Moreover, given that hematocrit is considered a key determinant of aerobic performance related to migration in birds, these findings highlight the need for investigating the effects of anti-androgenic chemicals on the hematology of migratory species for their conservation.

Effects of Phytosterols as Food Additives on Adrenal and Reproductive Endocrine Function during Sexual Maturation in Male Japanese Quail (Coturnix coturnix japonica).

Varying amounts of phytosterols (PS) occur naturally in several foods of plant origin. PS, which are structurally and functionally similar to cholesterol, have been shown to reduce plasma total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels. Moreover, PS disrupts endocrine function in certain animals. In the present study, we investigated the effects of high doses of PS on adrenal and reproductive endocrine function during sexual maturation in Japanese male quails. Two experiments were conducted; in the first experiment, quail chicks were subjected to long-term chronic feeding of PS (8, 80, and 800 mg/kg body weight [BW]) and the chemicals were gavaged into the crop sac from 7-50 days post-hatching. From the forty-fourth day, half of the animals in each group were subjected to a 6-day adrenocorticotropic hormone (ACTH) challenge for artificial stimulation of the adrenal gland and evaluation of long-term PS effects; in the second experiment, single doses of PS were subcutaneously injected (SC) into adult males (10-weeks-old) to assess the acute direct effect. Results indicated that chronically PS-fed animals showed a better adrenal response to ACTH challenge, and the corticosterone levels were higher (P<0.05) than those of the controls. Moreover, corticosterone levels were also high (P<0.05) 3 h after SC injection of PS. In contrast, testosterone levels and the testes weights were significantly lower (P<0.05) in the groups chronically administered with PS. No differences were observed in the testosterone levels in the acute experiment or luteinizing hormone (LH) levels in either experiment. In conclusion, the differential effects of PS on the adrenal gland and testis might be due to preferential use of different lipoprotein-cholesterol forms for steroid production. In addition, PS might locally perturb testosterone production by its accumulation or delay in testicular maturation.