Sex hormones change visceral pigmentation in Eupemphix nattereri (Anura): effects in testicular melanocytes and hepatic melanomacrophages

Abstract

Melanomacrophages and melanocytes are able to modify pigment intensity on the body surface as a response to temperature change, hibernation, hypoxia, infection, oxidative stress and exogenous use of hormones. This study evaluated the effect of the sex hormones 17β-estradiol and testosterone cypionate on the hepatic melanomacrophages and testicular melanocytes of Eupemphix nattereri under hyperestrogenic and hyperandrogenic conditions, eight days after daily hormonal administration as well as after a 15-day recovery period. Animals were injected subcutaneously with 17β-estradiol, testosterone cypionate or the carrier medium (as control). Histological analysis was used to examine the effect of the treatments. The results show that sex hormones altered the pigmentation of hepatic melanomacrophages and testicular melanocytes. Both liver melanomacrophages and testicular melanocytes in E. nattereri males displayed increased pigmentation after testosterone treatment, while estradiol decreased liver pigmentation only. This study describes, for the first time, the effects of sex hormones on visceral pigmentation of anura, showing the responsiveness of melanocytes and melanomacrophages to sex hormones.