Objective: Determination of the Naloxone opioid antagonist effect on the LH and FSH secretion in ewe in non-breeding season.
Design: Repeted measures.
Animals: Six zandi breed ewes with average (±SE) of weight and age, 42.4 ±4.2 and 760:t8 respectively and all of ewes had one birth.
Procedure: Ewes were received five injections of 0.5 or 0.2 mg naloxone/kg BW and followed by injection of 1 1 g gonadorelin /kg BW. Blood samples were collected every 15 minutes for 4 hours before injections until 4 hours after injections of naloxone and every 15 minutes for 1 hours after injection of gonadroline.
Statistical analysis: Analysis of variation.
Results: Mean plasma LH concentrations had been significantly increased in both groups after naloxone injections. LH pulses frequencies in both groups significantly increased after naloxone injections. Naloxone failed to alter pulsatile LH amplitudes in both groups. LH base concentrations increased in both groups after injections of naloxone but it was not significant. Also mean plasma LH concentrations had been significantly increased after gonadorelin injection. Mean plasma FSH concentrations, pulsatile frequencies, amplitudes and base concentrations of FSH did not change significantly.
Clinical Implications: The results of this study indicate that the opioids may affect on LH pattern secretion in the ewes in nonbreeding season, but the effect of opioid on FSH secretion is not observed.J.Fac. Vet. Med. Univ. Tehran. 59,4: 345-350,2004.
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