CENTRAL NEURAL SYSTEMS REGULATING ADRENAL TYROSINE HYDROXYLASE.

摘要

This work concerns the role of spinal sympathetic pathways in the transynaptic regulation of adrenal medullary tyrosine hydroxylase activity (ATHA) and catecholamines. Cord transection in adult rats above the origin of the sympatho-adrenal preganglionic neurons (SAPN) causes after 3 days progressive reductions of ATHA, of the Vmax for tyrosine hydroxylation and of adrenal dopamine content. These effects are prevented by prior splanchnicotomy; they may result from a lowering of modulatory impulses of decentralized SAPN. The effect of spinal section on ATHA is accentuated by the repeated injection of serotonergic and muscarinic agonists which could inhibit the SAPN. Following spinal hemisection at various levels, the responses of ATHA and of adrenal epinephrine content to immobilization stress or to administration of apomorphine, insulin or 2-deoxyglucose are mediated by direct and crossed descending projections from supraspinal neurons generating net facilitatory and possibly inhibitory effects. A high performance liquid chromatographic method with amperometric detection was developed to measure simultaneously the three main adrenal catecholamines.