Growth hormone response to baclofen in patients with mania: a pilot study.
BACKGROUND
Growth hormone (GH) response to a challenge with a GABAB receptor agonist, baclofen, is considered to provide an in vivo index of hypothalamic GABAB receptor function in humans.


OBJECTIVE
The purpose of this study was to explore the role of GABAB receptors in the pathophysiology of mania by measuring plasma GH response to baclofen in ten manic patients and ten matched healthy controls.


METHODS
After obtaining blood samples for baseline GH levels, a single dose of 20 mg baclofen was administered orally to all the subjects, and further blood samples were obtained at 30-min intervals for the following 3 h.


RESULTS
We found that baclofen administration led to a significant increase in GH release both in manic patients and healthy controls, but the GH response to baclofen in manic patients was significantly enhanced when compared to healthy controls.


CONCLUSIONS
Our results suggest that manic patients may have an up-regulated hypothalamic GABAB receptor function. However, in light of the limitations including small sample size and absence of placebo control, our results should be viewed as preliminary. Further studies with a larger number of manic patients and a placebo control design are needed to replicate our finding before any firm conclusion can be drawn.
Shiah
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Department of Psychiatry, University of British Columbia, Vancouver, Canada.
Yatham
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Lam
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Tam
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Zis
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AP
D000208:Acute Disease; D000328:Adult; D019540:Area Under Curve; D001418:Baclofen / Q000494:pharmacology*; D001714:Bipolar Disorder / Q000097:blood* / Q000523:psychology; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology*; D058786:GABA-B Receptor Agonists; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D013997:Time Factors
D018755:GABA Agonists; D058786:GABA-B Receptor Agonists; D019382:Human Growth Hormone; D001418:Baclofen