Changes in biochemical composition of follicular fluid during reproductive acyclicity in water buffalo (Bubalus bubalis)

Expression of Kisspeptin and its receptor in the hypothalamus of cyclic and acyclic buffalo (Bubalus bubalis)

Kisspeptin (Kiss1), neurokinin-B (NKB) and dynorphin (Dyn) neurons regulate the surge and pulsatile centres of gonadotropin releasing hormone (GnRH) in the hypothalamus and are modulated by the ovarian steroids. Accordingly, we studied the temporospatial expression of Kiss1, its receptor and other genes that regulate GnRH in the preoptic area (POA) and arcuate (ARC) regions of hypothalamus at different phases of bubaline estrous cycle. Brain of buffalo (n = 32) was collected immediately after exsanguination and categorized into early luteal (EL), mid luteal (ML), follicular (FL) stages and acyclic (n = 8/group). Total RNA was extracted from the POA and ARC of each stage and real time PCR amplification of Kiss1, Kiss1r, NKB, NKB receptor (NKBR), Dyn, Dyn receptor (OPRK1), GnRH1, ERα, PR, LEPR and GHSR was done using GAPDH as endogenous control and acyclic stage as calibrator group. Further, immunolocalization of Kiss1 and Kiss1r was done on the hypothalamus. In the POA, significant up-regulation of Kiss1 and NKB with a concomitant down-regulation of Dyn transcripts was recorded at FL stage. There was, however, down-regulation of Kiss1 and Kiss1r during the EL perhaps due to the loss of estradiol as a consequence of ovulation. On the other hand, in the ARC, there was a significant up-regulation of Kiss1 and Dyn at FL and ML, while NKB transcript was consistently down-regulated at any stage of estrous cycle. In the POA, expression of ERα was not modulated; however, PR was down-regulated in the EL. In the ARC, the ERα expression was significantly up-regulated in the EL, whereas, PR was moderately expressed irrespective of the stage of estrous cycle. The immunolocalization study revealed the presence of Kiss1 and Kiss1r in the POA and ARC in the cyclic buffalo with relative abundance at FL. The transcriptional profile of the genes suggests that there is estrous cycle stage specific expression of Kiss1, Kiss1r and other GnRH regulating genes in the POA and ARC regions of hypothalamus in the buffalo. Up-regulation of Kiss1r in the POA during ML and ARC during EL indicates the involvement of kisspeptinergic system in the regulation of low LH pulse frequencies during the early and mid luteal phases in the cyclic buffalo.

Follicular fluid stimulates capacitation and acrosome reaction in alpaca sperm (Vicugna pacos)

The follicular fluid exerts an effect on the sperm capacitation of several species; however, these effects vary according to species, both in the sperm motility and in the subsequent acrosome reaction. In this study, the effect of alpaca follicular fluid (aFF) on the motility and acrosome reaction of alpaca spermatozoa was observed, using follicular fluid of three follicle sizes: small (<3 mm), medium (3-6 mm) and large (>6 mm), in a concentration of 30%. Sperm motility at the first hour of incubation with aFF of small follicles was 48.0%, with aFF of medium follicles it was 43.33% and with aFF of large follicles, it was 34.53%, while control averaged 26.00%. At the second hour, control achieved an average of 28.13%, treatment with aFF from small follicles showed an average of 46.53%, with aFF from medium follicles it was 40.00% and with aFF from large follicles it was 35.60%. The acrosome reaction after 4 hours of incubation was 30.06% for control, whereas for aFF of small follicles it was 66.3%, with aFF of medium follicles it was 58.86% and for aFF of large follicles, it was 67.63%. In the case of sperm motility, a significant difference is demonstrated for all treatments in relation to the control at the first hour, whereas only the treatments with aFF of small and medium follicles show a significant difference with respect to the control at the second hour. In the case of the acrosome reaction, all treatments with follicular fluid show a significant difference with respect to the control. It was concluded that alpaca follicular fluid favours sperm capacitation and the acrosome reaction in alpaca spermatozoa.

Insulin signalling and glucose transport in the ovary and ovarian function during the ovarian cycle

Data derived principally from peripheral tissues (fat, muscle and liver) show that insulin signals via diverse interconnecting intracellular pathways and that some of the major intersecting points (known as critical nodes) are the IRSs (insulin receptor substrates), PI3K (phosphoinositide kinase)/Akt and MAPK (mitogen-activated protein kinase). Most of these insulin pathways are probably also active in the ovary and their ability to interact with each other and also with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) signalling pathways enables insulin to exert direct modulating influences on ovarian function. The present paper reviews the intracellular actions of insulin and the uptake of glucose by ovarian tissues (granulosa, theca and oocyte) during the oestrous/menstrual cycle of some rodent, primate and ruminant species. Insulin signals through diverse pathways and these are discussed with specific reference to follicular cell types (granulosa, theca and oocyte). The signalling pathways for FSH in granulosa cells and LH in granulosa and theca cells are summarized. The roles of glucose and of insulin-mediated uptake of glucose in folliculogenesis are discussed. It is suggested that glucose in addition to its well-established role of providing energy for cellular function may also have insulin-mediated signalling functions in ovarian cells, involving AMPK (AMP-dependent protein kinase) and/or hexosamine. Potential interactions of insulin signalling with FSH or LH signalling at critical nodes are identified and the available evidence for such interactions in ovarian cells is discussed. Finally the action of the insulin-sensitizing drugs metformin and the thiazolidinedione rosiglitazone on follicular cells is reviewed.

Seasonal changes in some oxidant and antioxidant parameters during folliculogenesis in Egyptian buffalo

Knowledge regarding oxidant and antioxidant status in follicular fluid remains limited and its studying in vivo should enhance our understanding of the impact of them on fertility and contribute to optimization of in vitro maturation conditions. The present study was conducted on follicular fluid and serum samples obtained from 708 buffaloes. They were examined for Malondialdehyde (MDA) as indicator of lipid peroxidation as well as superoxide dismutase (SOD) and total antioxidant capacity (TAC) as antioxidant markers. The obtained results revealed that MDA levels and SOD activity in follicular fluid decreased significantly as follicle size increased, while TAC increased significantly with the increase in follicular size. Whereas MDA level was significantly higher in summer, the TAC was significantly higher in spring. Moreover, MDA levels and SOD activities were significantly higher in the follicular fluid from different size follicles during the luteal phase than follicular phase. MDA levels in medium follicles in luteal phase and small follicles in follicular and luteal phases were significantly higher in summer than other seasons. Serum MDA levels were significantly increased in summer. In addition, MDA levels, SOD activities and TAC in serum were significantly higher during luteal phase than follicular phase in summer. TAC levels were significantly higher in follicular fluid than serum, while MDA was significantly lower in follicular fluid than serum. In conclusion, the present study revealed that oxidants/antioxidants balance may play a role in normal follicular development and oxidative stress that occur in summer could be related to reproductive seasonality in buffalo.