The androgen-conjugating uridine diphosphoglucuronosyltransferase-2B enzymes are differentially expressed temporally and spatially in the monkey follicle throughout the menstrual cycle

UDP-glucuronosyltransferase (UGT) enzymes enhance the polarity of steroid h ormones by catalyzing their conjugation with the sugar group from UDP-glucu ronic acid. Previous results have shown that the monkey is a suitable anima l model to study steroid glucuronidation in steroid target tissues. In huma ns, as in the monkey, the main androgen metabolites found in the circulatio n are 5 alpha -androstane-3 alpha ,17 beta -diol-glucuronide and androstero ne glucuronide, and high levels of androsterone glucuronide were also measu red in human follicular fluid. Ovarian androgens play a significant role as precursors for estrogens and may modulate the recruitment and growth of fo llicles. To analyze the expression pattern of UGT2B enzymes involved in and rogen metabolism throughout the menstrual cycle, cynomolgus monkey ovaries were collected during the mid and late follicular and luteal phases. Micros omal proteins and total RNA were analyzed for UGT2B expression in the whole ovary. Western blot and specific RT-PCR analyses demonstrated no significa nt changes in the expression of UGT2B protein or transcripts during the men strual cycle. Immunocytochemistry analysis showed that UGT2B proteins are e xpressed in the cytoplasm of thecal and granulosa cells of growing follicle s. Interestingly, the thecal cells of secondary follicles and of corpus lut eum were extensively stained, whereas luteal granulosa cells were not label ed. These results suggest an important regulation of cell type-specific UGT 2B expression during follicular development. Previous results demonstrated similar changes in the expression of the androgen receptor. The colocalizat ion of the androgen receptor and UCT2B enzymes in the same cell types of th e ovary provide evidence for a potential role of glucuronidation as a modul ator of the intracellular androgen response during follicular development.