beta-endorphin binding sites in pars distalis of the frog, Rana esculenta

The participation of POMC-derived peptides in the control of reproductive function is not clear; however, evidence indicate that in mammals the opioid peptide beta-endorphin (beta-EP), has a physiological role in regulating pituitary hormone secretion, including gonadotropins. To investigate this aspect, we assessed whether beta-EP binding sites would be present in pars distalis, and the wild population of anuran Rana esculenta was considered a good model; therefore, beta-EP specific binding sites were visualized by confocal laser scanning microscopy in primary cell culture.