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Oxytocin release induced by melatonin in the ewe
Developmental Pharmacology and Therapeutics
|January 1, 1985
Summary
Melatonin, a pineal gland hormone, may influence mammalian estrus cycles. This study found melatonin increased oxytocin levels in nonpregnant ewes, suggesting a reproductive interaction.
Area of Science:
- Reproductive Endocrinology
- Neuroendocrinology
- Mammalian Physiology
Background:
- The pineal gland hormone melatonin is a key regulator of estrus timing in mammals.
- Neurohypophyseal nonapeptides, arginine vasotocin and oxytocin, have been detected in mammalian pineal glands.
- Potential interactions between melatonin and these neurohypophyseal hormones warrant investigation.
Purpose of the Study:
- To investigate the potential interaction between melatonin and neurohypophyseal hormones (arginine vasotocin and oxytocin).
- To determine if melatonin influences the plasma levels of arginine vasotocin and oxytocin in ewes.
Main Methods:
- An acute infusion of melatonin (216 mumol) was administered to both pregnant and nonpregnant ewes.
- Plasma levels of arginine vasopressin, arginine vasotocin, and oxytocin were measured before and after melatonin administration.
Main Results:
- Melatonin infusion did not alter plasma arginine vasopressin or arginine vasotocin levels in either pregnant or nonpregnant ewes.
- A significant increase in plasma oxytocin was observed in nonpregnant ewes following melatonin infusion.
- This effect on oxytocin was not observed in pregnant ewes.
Conclusions:
- Melatonin may interact with oxytocin in the regulation of mammalian reproductive cycles.
- The findings suggest a potential role for melatonin-oxytocin interplay in estrus timing, particularly in nonpregnant states.