Therapeutical doses of salbutamol inhibit the somatotropic responsiveness to growth hormone-releasing hormone in asthmatic children

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Abstract
In humans β-adrenergic receptors mediate an inhibitory effect on somatotropic function, likely via stimulation of hypothalamic somatostatin release. Accordingly, salbutamol (SAL), a β2-agonist, given iv abolishes the GH response to GH-releasing hormone (GHRH) in adults. Taking into account that in bronchial asthma an alteration in the β-adrenergic neural control of airways has been hypothesized, we aimed to verify whether, in asthmatic children, β-adrenergic activation inhibits or not GH secretion. To this goal, we studied the effect of therapeutical doses of SAL on GH response to GHRH in 15 asthmatic children (12 M and 3 F, 5.9–11.1 yr, pubertal stage l-ll). All children underwent a GHRH test (1 µg/kg iv). Moreover, in 7 children (group A), SAL was administered orally (0.125 mg/kg) 1 h before GHRH, while in 8 (group B) by inhaled aerosol (2 mg) 30 min before GHRH. Oral SAL (group A) abolished the GHRH-induced GH rise (AUC, mean±SE 165.1±33.3 vs 959.9±158.1 µg/L/h; pvs 1378.8±315.6 µg/L/h; p