A role for @entity935 in growth hormone regulation in the XXXX .

@entity7831 @entity1766 @entity1 @entity935 @entity235 @entity5521 @entity391 @entity3826 @entity1767 @entity2211 @entity3897 @entity1063
The role of @entity935 (DA) in the secretion of GH in most animal species is still controversial. We examined in the @entity235 the effect on GH release of @entity7831 , a drug which activates both noradrenergic and dopaminergic neurotransmission. @entity7831 (0.4-2.8 mg/kg, iv), administered into 12 unanesthetized male and female beagles, induced short-dose-related rises in @entity235 GH (cGH) levels. Blockade of alpha-adrenergic receptors by @entity5521 prevented the GH stimulatory effect of 2.8 mg/kg @entity7831 , and an iv bolus injection of @entity1767 (a neuroleptic which antagonizes both @entity1063 and DA receptor function) given 45 min before was equally effective. Selective blockade of DA receptors by @entity1766 significantly reduced the GH-releasing effect of @entity7831 . In sum, these data indicated that the effect of @entity7831 was the consequence of an enhanced noradrenergic and dopaminergic-neurotransmission. Pretreatment with @entity2211 , a DA receptor blocker unable to cross the blood-brain barrier, failed to modify the GH-releasing effect of @entity7831 , suggesting that the DA component subserving the neuroendocrine effect of the drug lies within the blood-brain barrier. Further evidence for a stimulatory role of DA on GH release was the fact that @entity3826 , a direct stimulant of DA receptors, induced a rise in cGH levels when administered to @entity235 pretreated with @entity2211 . The latter drug was used to prevent @entity391 and distress due to activation of peripheral DA receptors by @entity3826 . However, @entity3826 was only active in the @entity235 at doses (250 and 500 microgram/kg, sc) greatly exceeding those active in releasing GH in @entity1 , suggesting that the role of DA in cGH regulation is ancillary to that exerted by noradrenergic neurotransmission. In a final study, @entity3897 , a muscarinic cholinergic receptor antagonist, abolished the neuroendocrine effect of @entity7831 , a finding which suggests that cholinergic medication plays an important role in cGH regulation.
