Leptin and Pregnancy: preliminary results in buffalo cows (Bubalus bubalis)

Leptin is a 16.4 kDa peptide hormone, encoded by the obese gene (ob) and synthesized mainly by adipocytes, but gene expression has been found in several additional peripheral tissues such as placenta and fetal tissues, mammary gland, brain and pituitary, stomach, skeletal muscle, duodenum, abomasum and calf rumen. Beyond the primary role in food intake and energy expenditure, leptin has been implicated in numerous regulatory functions, including glucose metabolism, lipid oxidation, endocrine system, blood pressure, haematopoiesis, angiogenesis, brain and bone development, wound healing and cell differentiation and proliferation. Recent findings suggest that leptin could be implicated in important reproductive process such as embryonic development and implantation. Thus, the aim of the present study was to verify whether the maternal blood concentrations of leptin may be related to the successful establishment and maintenance of pregnancy in buffalo. Thirteen buffalo cows that become pregnant after artificial insemination (group A) and 13 that did not conceived (group B) were used. Blood samples were collected at day 0, 14, 23, 25, 28 and 40 from both groups, plus at day 60 and 80 in pregnant animals (day 0 = AI) for leptin, progesterone (P4) and pregnancy-associated glycoproteins (PAG). Starting from day 0, plasma leptin concentrations were constantly low in all the cows that failed to conceive (3.44 +/- 0.94 ng/mL), while constantly high levels were found in animals become pregnant (19.7 +/- 2.85 ng/mL). The present data appear to show a relationship between the concentration of leptin in maternal blood and the ability of buffalo cows to become pregnant.