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Published on: September 7, 2013
Reversal by vasotocin of pinealectomy and constant light effects on the pituitary melanocyte-stimulating hormone
Abstract:
A single injection of 1 pg synthetic arginine vasotocin (AVT) into the third ventricle of the mouse completely prevented the pituitary MSH increase which occurs seven days after pinealectomy or 24 h after exposure to constant light. The same concentration of AVT injected into the third ventricle of normal mice markedly decreased the pituitary MSH content at 20 min following the injection. The present results suggest that AVT injected into the third ventricle of the mouse inhibits synthesis and/or release of MSH-release inhibiting factor (MIF).
Insights
Arginine vasotocin (AVT) prevents pituitary MSH increases after pinealectomy or constant light exposure. This suggests AVT inhibits the synthesis or release of melanocyte-stimulating hormone-release inhibiting factor (MIF).
Area of Science:
- Neuroendocrinology
- Hormone regulation
- Pituitary gland function
Background:
- Pinealectomy and constant light exposure disrupt normal hormonal rhythms.
- Melanocyte-stimulating hormone (MSH) regulation involves complex feedback mechanisms.
- The role of arginine vasotocin (AVT) in MSH regulation is not fully understood.
Purpose of the Study:
- To investigate the effect of centrally administered AVT on pituitary MSH levels in mice.
- To determine if AVT influences MSH regulation following pinealectomy or constant light exposure.
Main Methods:
- Intraventricular injection of synthetic AVT in mice.
- Measurement of pituitary MSH content at various time points.
- Experimental groups included pinealectomized mice, mice exposed to constant light, and normal control mice.
Main Results:
- A single 1 pg injection of AVT into the third ventricle completely prevented the MSH increase observed after pinealectomy or constant light exposure.
- In normal mice, the same AVT concentration significantly decreased pituitary MSH content within 20 minutes.
- These findings indicate a potent inhibitory effect of AVT on MSH regulation.
Conclusions:
- Central administration of AVT inhibits the synthesis and/or release of melanocyte-stimulating hormone-release inhibiting factor (MIF).
- AVT plays a significant role in modulating MSH secretion, potentially via its influence on MIF.
- Further research is warranted to elucidate the precise mechanisms of AVT-MIF interaction in neuroendocrine control.
