Activation of alpha1-adrenoceptors inhibits growth hormone secretion in humans

In order to determine whether an alpha1-adrenergic mechanism is involved in the secretion of Growth Hormone (GH) in humans, we studied the effect of the alpha1-adrenergic-stimulating agent methoxamine on serum GH levels in twelve normal males (age range 22-32 years). Intravenous infusion of methoxamine (dose: 6 microg/kg/min; duration: 150 min) significantly reduced serum GH levels at time 120 and 150, and on integrated concentrations. These data suggest that alpha1-adrenergic receptors inhibit tonic GH secretion in humans.