Comparison of pre-and postpartum serum leptin, ghrelin, and lipid levels in sheep

Abstract

Serum leptin and ghrelin play important roles in energy metabolism and inducing appetite during pregnancy and lactation. We investigated the serum levels of leptin and ghrelin and their relationship with the duration of lactation and serum biochemical responses during the prepartum (last week before lambing) and postpartum periods in sheep. They were also evaluated between pregnant and nonpregnant (control ewes) ewes. For these purposes, pregnant (n = 15) and control Awassi ewes (n = 15) that were 2 years of age were used in this study. Blood samples were collected 1 week before the expected date of lambing (baseline) and for 12 weeks after parturitions. Serum leptin, ghrelin, cholesterol, triglyceride, VLDL, LDL, HDL, NEFA, and phospholipid levels were assayed. Leptin and ghrelin levels of the prepartum period in pregnant and control ewes were 4.5 ng/mL and 3.4 ng/mL (P < 0.05) and 75 pg/mL and 166 pg/ mL (P < 0.01), respectively. The baseline value of ghrelin (81 pg/mL) decreased to 43 pg/mL within 1 week after parturition (P < 0.01). Serum ghrelin levels increased after 1 week. There was also a significant difference in serum ghrelin levels between control ewes and those a week before parturition in pregnant ewes (P < 0.001). The NEFA level was higher in pregnant than in control sheep (P < 0.001). In conclusion, leptin levels tended to decrease during the lactation period, which could be associated with a negative energy balance. Additionally, ghrelin levels tended to gradually increase during lactation to adapt to a negative energy balance. We think that variations in serum leptin and ghrelin might be used to monitor metabolic adaptation during lactation.