Background: Leptin, the product of the obesity (ob) gene, acts as a signaling adipokine for modulating food intake, energy metabolism and reproductive functions in mammals. Leptin’s effects on the reproductive system at various levels of the hypothalamic-pituitary-gonadal axis have been established. Moreover, the direct and local effect of leptin on bovine oocyte maturation and corpus luteum function has been determined. Objectives: Due to species differences, this study was designed to investigate expression of leptin mRNA as well as its long isoform receptor (Ob-Rb) mRNA in sheep corpus luteum. Methods: Ovaries of sheep containing mature corpus luteum were collected in the reproductive season from abattoirs. Total RNA of corpus luteum was extracted, cDNA synthesis was carried out subsequently and PCR reaction was performed using primers which were designed specifically for each gene. Beta-actin was used as housekeeping gene to verify reactions, and adipose tissue was selected as positive sample for expression of leptin and leptin receptor. Results: Gel electrophoresis of PCR products showed the amplification of 162 and 121-bp amplicons in all samples for leptin and leptin receptor respectively. Moreover, sequencing the amplified fragments and blasting them confirmed the accuracy of results. Conclusion: Our findings confirm the expression of leptin and its functional receptor transcripts in ovine corpus luteum. More studies for determining leptin effects on corpus luteum are guaranteed.

Background:Ghrelin, an endogenous ligand for the growthsecretagogue receptor is predominantly produced in the stomach and anexpression of ghrelin has recently been identified in placenta and ovary. OBJECTIVES: Therefore, we decited to measure ovarian ghrelin as quantitative andevaluate the correlation between ghrelin and estrogen during second half ofovine pregnancy. METHODS: The ovarian samples were collected from 40pregnant sheep in 3, 3.5, 4, 4.5 and 5 months of pregnancy in a local abattoir.Follicles and active corpora lutea (CL) were dissected from surroundingtissues, separately. The samples were homogenized with phosphate buffer (0.1 M,pH=7.4) on liquid nitrogen to provide fluid samples. Ghrelin and estrogenconcentrations were measured by ELISA method and expressed as milligram (mg)and picogram (pg) per mg of tissue protein, respectively. RESULTS:There was a linear correlation between ghrelin and estrogen in ovarian follicles(r=0.97 and p=0.004), but not in CL. Follicular ghrelin significantly increasedin 4, 4.5 and 5 months (p<0.001) but CL ghrelin significantly decreased inthe 4.5 month of ovine pregnancy (p<0.01). Estrogen concentration was alsosignificantly higher in 4-5 months of pregnancy in ovarian follicles(p<0.001) but potent CL indicated higher estrogen level only in the 5thmonth of pregnancy (p<0.001). CONCLUSIONS:These results emphasize the role of ghrelin inthe reproductive system and open a new window to future studies