Effects of neonatal 6-hydroxydopamine administration on different substance P-containing sensory neurones.
Rats were treated neonatally with 6-hydroxydopamine. This resulted in a greater than 93% depletion of noradrenaline content of all tissues examined in adult animals. There was a significant increase in the substance P content of semilunar ganglion, L5 dorsal root ganglion and of sciatic nerve. There was a corresponding increase in substance P synthesis as measured by axonal transport in the sciatic nerve. The noradrenaline content and ratio of noradrenaline: substance P in the iris of control animals were 2102 pg/mg and 24 respectively and, confirming the results of other workers, 6-hydroxydopamine treatment caused a doubling of this substance P content. Terminal fields in skin of face and paw had noradrenaline contents of 75 and 41 pg/mg respectively and noradrenaline: substance P ratios of 4.0 and 2.2 respectively and in these areas 6-hydroxydopamine treatment caused a much lesser increase in substance P content. We conclude that the response of sensory neurones to 6-hydroxydopamine is governed by the relative density of the sympathetic and sensory innervations in their terminal areas, possibly reflecting intensity of competition for nerve growth factor.
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001369:Axons / Q000378:metabolism; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000187:drug effects / Q000378:metabolism; D013373:Substance P / Q000502:physiology*; D013563:Sympathectomy, Chemical; D014276:Trigeminal Nerve / Q000187:drug effects / Q000378:metabolism
D006892:Hydroxydopamines; D013373:Substance P; D016627:Oxidopamine; D009638:Norepinephrine