Intrinsic control of cerobro-vascular tone-role of central nor-advenergic system

点击翻译按钮获取中文摘要

We have investigated the role of the central dorsal and rentral noradrenergic systems (Locus Coeruleus Complex, LC, Medullary Reticular Formation, MRF) and the cholinoceptive pontine area (CPA) in control of cerebral vasomotor tone. The experiments were performed on 30 chloralose-anesthetized cats with or without Kaolin induced hydrocephalus.[I] Microinjection of glutamate or carbochol into the LC or the MRF induced decrease of ICP in association with a slight rise of BP.On the other hand microinjection of carbachol or Ach into the CPA produced "plateau wave" like ICP-variations.[II] Tonic discharges of the LC neuron were gradually suppressed at 10 to 30 sec. prior to the onset of plateau waves, almost completely silenced during the plateau phase. Tonic MRF-neuron discharges were gradually suppressed about 30 sec. before onset o fplateau wave like ICP-variations and sharply suppressed during the plateau phase. Recovery began 10 to 30 sec. before the ICP decrease. On the other hand, the firing rate of the CPA-neuron was increased in phase with the plateau waves.[III] Electrophysiological studies show that the CPA neurons suppress both the LC and MRF-neurons which make up the central noradrenergic system. Activation of the CPA neurons should suppress activity in the central noradrenergic system. The increase in CBV then occurrs in response to dilatation of cerebral vessels.These results suggest that activity within the CPA, LC and MRF contributes to ICP changes and is the endogenous neuronal origin of plateau waves occurring in some conditions such as Kaolin induced hydrocephalus.