Different control mechanisms of growth hormone (GH) secretion between gamma-amino- and gamma-hydroxy-butyric acid: neuroendocrine evidence in Parkinson's disease.
The observation that baclofen stimulates growth hormone (GH) secretion in normal men, but not in parkinsonian patients led us to test the GH releasing effect of other gamma-amino-butyric acid (GABA)ergic agents with different mechanisms of action in Parkinson's disease. For this purpose 10 normal men and 10 de novo parkinsonian patients were tested with sodium valproate (800 mg PO), gamma-hydroxybutyric acid (GHB) (25 mg/kg body weight PO) and baclofen (10 mg PO). All drugs induced a significant increment in serum GH levels in the normal controls. On the other hand, GH secretion in parkinsonian patients did not change after baclofen or sodium valproate administration, whereas it showed normal responsiveness to GHB. These data suggest that the mechanism underlying the GH response to GHB is different from that (or those) mediating sodium valproate and/or baclofen action. In addition, the former, but not the latter mechanism appears to be preserved in the parkinsonian brain.
Volpi
R
R
Department of Internal Medicine, School of Medicine, University of Parma, Italy. volpi@ipruniv.cce.unipr.it
Chiodera
P
P
Caffarra
P
P
Scaglioni
A
A
Saccani
A
A
Coiro
V
V
D000368:Aged; D001418:Baclofen; D018682:GABA Agents; D018755:GABA Agonists / Q000494:pharmacology; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood / Q000378:metabolism*; D012978:Sodium Oxybate / Q000097:blood*; D014635:Valproic Acid; D005680:gamma-Aminobutyric Acid / Q000097:blood*
D018682:GABA Agents; D018755:GABA Agonists; D005680:gamma-Aminobutyric Acid; D014635:Valproic Acid; D012978:Sodium Oxybate; D013006:Growth Hormone; D001418:Baclofen