EFFECTS OF ADRENERGIC AGENTS ON VENTRAL HORN CELLS IN RAT SPINAL CORD SLICES

Abstract

The effects of noradrenaline, and of other adrenoceptor agonists and antagonists on the synaptic activity of ventral horn cells were investigated using spinal cord slices prepared from adult rats. Noradrenaline (0.03-3 μM) facilitated the cell discharges induced by local stimulation of the ventral horn. The facilitation was abolished by prazosin but not by propranolol or yohimbine. In the presence of prazosin, noradrenaline (1-3 μM) reduced cell discharges, and the suppression was abolished by yohimbine. Phenylephrine, methoxamine and clonidine facilitated the neuronal activity. In the presence of prazosin, clonidine but not phenylephrine reduced the cell discharges. It is suggested that the facilitation and suppression ofsynaptic activity produced by noradrenaline are mediated through α₁- and α₂-adrenoceptors respectively, and that facilitatory action through α₁-adrenoceptors is dominant in adrenergic transmission in the motor nuclei of the ventral horn.