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Clonidine lowers alpha-MSH-like immunoreactivity in human plasma
P Limone1, V D'Alessandro, I Rainero
1Institute of Internal Medicine, University of Turin, Italy.
Life Sciences
|January 1, 1993
Summary
Clonidine, a selective alpha 2 receptor stimulator, was found to significantly lower plasma alpha-melanocyte-stimulating hormone (alpha-MSH-LI) concentrations in healthy subjects. This suggests distinct regulatory pathways for pituitary peptide secretion.
Area of Science:
- Neuroendocrinology
- Pharmacology
Background:
- Alpha-melanocyte-stimulating hormone (alpha-MSH) is a key peptide in the pro-opiomelanocortin (POMC) family.
- The regulation of POMC-derived peptides, including alpha-MSH, ACTH, and cortisol, involves complex pituitary mechanisms.
Purpose of the Study:
- To investigate the effect of clonidine, a selective alpha 2 receptor agonist, on plasma alpha-MSH-LI concentrations.
- To explore the potential involvement of alpha 2 adrenergic receptors in the regulation of alpha-MSH secretion.
Main Methods:
- Acute intravenous administration of clonidine (0.075 mg) or saline in seven healthy subjects.
- Measurement of plasma alpha-MSH-LI, ACTH, and cortisol concentrations at various time points post-administration.
Main Results:
- Clonidine significantly reduced plasma alpha-MSH-LI concentrations compared to saline.
- The maximum decrease in alpha-MSH-LI occurred between 30 and 60 minutes, returning to baseline by 120 minutes.
- No significant changes were observed in plasma ACTH and cortisol levels.
Conclusions:
- Clonidine administration suppresses alpha-MSH-LI secretion in humans.
- Separate regulatory mechanisms likely control POMC peptide release from human pituitary corticotroph and melanotroph cells.