اثر محرك لپتين بر ترشح گونادوتروپينها در ميشهاي تحت محدوديت انرژي

Stimulatory Effect of Leptin on Gonadotropins Secretion in Energy-Restricted Ewes

This study was conducted to investigate the effect of intravascular (peripheral) leptin injection on gonadotropins secretion in energy-restricted ewes. Six acyclic (LH pulses secretion lacking) Chal ewes each received 250 µg cloprostenol one day prior to treatment (day 0). Ewes were assigned to two groups (n=3), receiving the following treatments for a duration of 4 days. Groups 1 and 11 received intravenous injection with 1 µg and 4 µg/Kg BW leptin, respectively. Ewes were fed a ration that provided 60% of the maintenance energy requirements. Blood samples were collected (3 ml) at 20 minutes and hourly intervals for 3 hours on days 0 and 5 (before feeding) to determine LH and FSH secretion pattern. In addition, blood samples were collected for 3 hours before and after leptin injection on days 2 and 4 the same way as above. Ovulation rate was also dctenuined after treatment period through laparoscopy. Mean plasma concentration (p<0.05), pulse frequency (p<0.01), and LH amplitude (p<0.05) as well as mean plasma FSH concentration (p<0.01) were significantly increased in either groups. Ovulation rate was not affected. The Results indicate that intravascular (peripheral) leptin injection can restore gonadotropins secretion (limited in energy-restricted ewes).