ALPHA-ADRENERGIC, NEUROKININ AND MUSCARINIC RECEPTORS IN RAT MESENTERIC-ARTERY - AN MESSENGER-RNA STUDY DURING POSTNATAL-DEVELOPMENT

Developmental studies show that the innervation of autonomic targets i s accompanied by increases in the density of receptors, maturation of receptor-signalling pathways and changes in receptor subtype. The inne rvation of the rat mesenteric artery occurs over the first 3 postnatal weeks. In this study, we investigated whether alterations in receptor gene expression may underlie physiological changes recorded during de velopment and maturity in this vessel; Total RNA, from mesenteric arte ries of rats at birth and postnatal days 7, 14, 28, 240 and 360, was r everse transcribed and amplified using primers specific for the alpha( 1(A, B, D))- and alpha(2(A, B, C))-adrenergic, neurokinin (NK1-NK3) an d muscarinic (m(1)-m(5)) receptors. Results showed that all receptor g enes expressed at 28 days, except the alpha(1D)-adrenergic receptor, w ere already expressed at birth. Some receptor subtypes showed no chang e in their relative expression, always being either strongly (alpha(1A ), alpha(2B), NK3) or weakly (alpha(2A), alpha(2C), NK1) expressed. Re lative to the expression of these receptors, others showed a developme ntal increase in expression up to 14 days postnatal (alpha(1B), alpha( 1D), m(2), m(3), m(5)) but no further change with maturity. These latt er changes coincide with the development of sympathetic and sensory ne rve plexuses in the mesenteric artery, but do not correlate with the p hysiological changes seen during development and ageing. (C) 1996 Else vier Science Ireland Ltd.