Gender differences in brain metabolic and plasma catecholamine responses to alpha 2-adrenoceptor blockade.
alpha 2-Adrenergic receptors modulate the release of several neurotransmitters implicated in the treatment and pathophysiology of mood and anxiety disorders. Significant sex differences occur in the prevalence of both disorders. To test whether gender affects alpha 2 function, the plasma catecholamine and brain metabolic responses to alpha 2 blockade were measured in male and female volunteers. Ten female and thirteen male volunteers underwent [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans before and after infusion of idazoxan (200 micrograms/kg). Measures of plasma catecholamines, blood pressure, and anxiety were obtained. Norepinephrine responses were larger in males. Women showed global increases in metabolism, whereas males had no global changes and some regional decreases in FDG uptake following idazoxan administration. The differences in norepinephrine increases are consistent with previously reported effects of gender on sympathetic activation. The PET data suggest gender differences in responses to alpha 2-receptor blockade in brain as well.
Schmidt
M E
ME
Experimental Therapeutics Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA.
Matochik
J A
JA
Goldstein
D S
DS
Schouten
J L
JL
Zametkin
A J
AJ
Potter
W Z
WZ
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000493:pharmacokinetics / Q000494:pharmacology*; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects*; D002395:Catecholamines / Q000097:blood*; D003847:Deoxyglucose / Q000031:analogs & derivatives; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D019329:Idazoxan / Q000493:pharmacokinetics / Q000494:pharmacology; D008297:Male; D012727:Sex Characteristics; D014055:Tomography, Emission-Computed
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D002395:Catecholamines; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose; D005947:Glucose; D019329:Idazoxan