Modulation of 6-hydroxydopamine induced alteration of the postnatal development of central noradrenaline neurons.
The effect of substance P and morphine on the 6-hydroxydopamine (6-OHDA) induced alteration of the postnatal development of central noradrenaline (NA) neurons in the rat has been investigated using neurochemical techniques. Neonatal administration of 6-OHDA systemically leads to permanent NA denervations of distant NA projections, while the projections close to the NA cell bodies are increased, leading to NA hyperinnervation. Intracisternal injection of substance P was found to counteract both the NA denervation and hyperinnervation induced by 6-OHDA. The effect of substance P disclosed a clear dose-dependent relationship. Morphine, on the other hand, was observed to potentiate the alterations induced by 6-OHDA, both the NA denervation and hyperinnervation. The effect of morphine was dose-dependent and could be blocked by the morphine antagonist naloxone. The present results give further support for the view that the 6-OHDA induced alteration of the postnatal development of central NA neurons is related to a "pruning effect." The data furthermore imply that the end-result from a 6-OHDA induced degeneration of central NA neurons during ontogeny may be modulated by the functional state of the neurons.
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects*; D002531:Cerebellum / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology*; D009020:Morphine / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism*; D009830:Olfactory Bulb / Q000187:drug effects; D016627:Oxidopamine; D051381:Rats; D013116:Spinal Cord / Q000187:drug effects*; D013373:Substance P / Q000494:pharmacology
D006892:Hydroxydopamines; D013373:Substance P; D009020:Morphine; D016627:Oxidopamine; D009638:Norepinephrine