The paradoxical response of growth hormone (GH) to thyrotropin-releasing hormone (TRH) in constitutionally tall children involves a cholinergic pathway

Abstract
To investigate whether or not a cholinergic pathway is involved in the paradoxical response of GH to TRH in constitutionally tall children, we studied 8 healthy prepubertal children aged $4^{2}/{_{_{12}}} - 7^{10}/{_{_{12}}} {? yr}$, whose heights were over the 95th percentile of the NCHS tables. We defined as ?paradoxical? a GH increment greater than 5 ng/ml in response to TRH. Five out of 8 children showed a paradoxical response of GH to TRH (mean GH peak after TRH of 10.7 ? 1.1 ng/ml). Pretreatment with atropine (0.01 mg/kg IM 30 min prior to the TRH administration) abolished the TRH induced GH rise (peak GH after TRH of 1.5 ? 1.0 ng/ml, p < 0.01) but did not modify the TSH response (peak TSH after TRH: basal conditions 8.7 ? 0.8 ?U/ml, post atropine: 9.5 ? 1.4 ?U/ml, p > 0.05). Our results demonstrate that a cholinergic pathway is involved in the paradoxical response of GH to TRH in constitutionally tall children.
Description
Keywords
Growth Hormone, Thyrotropin-Releasing-Hormone, Cholinergic Athway, Atropine, Tall stature
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