Effect of loperamide and naltrexone treatment on gonadotrophin concentration in the mare
Abstract
To investigate the involvement of opioids in the regulation of the reproductive axis, the
opioid agonist loperamide was given via stomach tube to oestrus mares. In order to
assess whether the opioid antagonist naltrexone is as effective as naloxone in overriding
the inhibition of endogenous opioid pep tides on luteinizing hormone (LH) and
follicle stimulating hormone (FSH) in the mare, naltrexone (NTX) was given to three
dioestrus and seven anoestrus mares. Mares were given 20 and 40 mg NTX i.v.. In a
third experiment, two anoestrus mares were given a dose of 80 mg NTX. Loperamide
had no significant effect on either LH or FSH plasma concentrations in jugular blood.
During dioestrus, both 20 and 40 mg NTX were effective in increasing LH and FSH
plasma concentrations significantly. During anoestrus, two mares responded to the 20
mg dose, while four responded to the 40 mg dose. One mare responded to the 80 mg
dose. These results encourage the use of the opioid antagonist naltrexone to study
opioid inhibition of LH and FSH in the mare.... [Show full abstract]
Keywords
opioids; loperamide; naltrexone; mare; reproductionFields of Research
070206 Animal Reproduction; 0707 Veterinary SciencesDate
1995Type
DissertationCollections
- Dissertations [445]
- Department of Agricultural Sciences [1445]