Abundance of adiponectin mRNA transcript in the buffalo corpus luteum during the estrous cycle and effects on progesterone secretion in vitro.

Adiponectin is an adipocyte derived cytokine implicated in energy homeostasis, insulin resistance and is involved in the regulation of reproduction both centrally and peripherally in animals. The present study was conducted to investigate adiponectin (ADIPOQ) and its receptors ADIPOR1 and ADIPOR2 abundance of mRNA transcript and protein in different stages of corpora lutea (CL) development during the estrous cycle of water buffalo and to determine the effect of adiponectin on cultured luteal cells of water buffalo (Bubalus bubalis). The results indicate adiponectin, ADIPOR1, and ADIPOR2 were present in buffalo corpora lutea (CL) throughout the estrous cycle. The abundance of adiponectin and its receptors was greater in the early and regressing and was less in mid- and late-stages of CL functionality. Adiponectin and its receptors were localized in the cytoplasm of small and large luteal cells. Furthermore, luteal cells were cultured in the in-vitro culture system and were treated with 1 and 10 µg/mL dose of adiponectin for 48 h. Adiponectin at both doses decreased (P < 0.05) progesterone (P4) secretion from cultured luteal cells and also suppressed the abundance of factors involved in P4productionv [Steroidogenic Acute Regulatory Protein (STAR), cytochrome P45011A1 (CYP11A1) and 3ß-hydroxysteroid dehydrogenase (HSD3B1) at the 10 µg/mL dose as compared to adiponectin non-supplemented cells]. In conclusion, results of the present study indicate adiponectin and its receptors are present in bubaline CL and adiponectin inhibits P4 production in cultured luteal cells. The findings indicate adiponectin affects luteal dynamics and reproductive functions in water buffalo.

Expression and localization of adiponectin and its receptors in ovarian follicles during different stages of development and the modulatory effect of adiponectin on steroid production in water buffalo.

Adiponectin is an adipocyte-derived hormone regulating energy metabolism, insulin sensitivity and recently found to regulate reproduction. The current study was carried out to investigate gene and protein expression, immunolocalization of adiponectin and its receptors AdipoR1 and AdipoR2 in ovarian follicles of different developmental stages in water buffalo (Bubalus bubalis) and to investigate the effect of adiponectin on steroid production in cultured bubaline granulosa cells. qPCR, western blotting and immunohistochemistry were applied to demonstrate mRNA expression, protein expression and immunolocalization, respectively. The results indicate that adiponectin, AdipoR1 and AdipoR2 were present in granulosa cells (GC) and theca interna (TI) of ovarian follicles and the expression of adiponectin, AdipoR1, AdipoR2 in GC and AdipoR1 and AdipoR2 in TI increased with increase in follicle size (p < .05). Expression of adiponectin was high in small and medium size follicles in TI. The adiponectin and its receptors were immunolocalized in the cytoplasm of GC and TI cells. Further, in the in-vitro study, GCs were cultured and treated with recombinant adiponectin each at 0, 1 and 10 µg/ml alone or with follicle stimulating hormone (FSH) at 30 ng/ml) or Insulin-like growth factor I (IGF-I) at 10 ng/ml for 48 hr after obtaining 75%-80%s confluency. Adiponectin at 10 µg/ml increased IGF-I-induced estradiol (E2 ) and progesterone (P4 ) secretion and FSH-induced E2 secretion from GC and also increased the abundance of factors involved in E2 and P4 production (cytochrome P45019A1 [CYP19A1] and 3-beta-hydroxysteroid dehydrogenase [3ß-HSD]). In conclusion, this study provides novel evidence for the presence of adiponectin and its receptors in ovarian follicles and modulatory role of adiponectin on steroid production in buffalo.