Journal of Neuroscience, Vol 1, 641-649, Copyright © 1981 by Society for Neuroscience
Cerebral compensation for chronic noradrenergic denervation induced by locus ceruleus lesion: recovery of receptor binding, isoproterenol- induced adenylate cyclase activity, and oxidative metabolism
SI Harik, RB Duckrow, JC LaManna, M Rosenthal, VK Sharma and SP Banerjee
The long term effects of specific noradrenergic denervation of rat cerebral
cortex were considered in parallel studies of in vitro noradrenergic
receptor binding and isoproterenol-induced adenosine 3':5'-monophosphate
(cycle AMP) generation and of in vivo oxidative metabolism. Noradrenergic
denervation was achieved by the local, unilateral injection of
6-hydroxydopamine into the locus ceruleus. Cerebral noradrenaline remained
depleted throughout the 8-week duration of the study. Ligand-binding assays
showed increased beta-adrenergic receptors 2 weeks after locus ceruleus
lesion with recovery occurring by 4 weeks. There were no changes in alpha
1-adrenergic receptors. Isoproterenol-induced cyclic AMP generation
increased at 2 weeks after lesion but recovered at 8 weeks. Dual wavelength
reflection spectrophotometric measurements of cytochrome oxidase
reduction/oxidation and local blood volume shifts, provoked in situ by
direct cortical stimulation, also demonstrated abnormalities at 2 weeks
with recovery by 4 weeks after lesion. Thus, in vivo and in vitro changes
after locus ceruleus lesion are reversible and the time course of these
changes is related temporally. These data suggest that cerebral cortex has
adaptive capabilities which are activated to compensate for prolonged
noradrenaline depletion. We also speculate that there may be a causal
relationship between the in vitro and in vivo parameters studied.