The ontogeny of spinal cord monoamines and the post-decapitation reflex.
The ontogeny of the post-decapitation reflex (PDR) was examined in neonatal systemic 6-hydroxydopamine (6-OHDA) treated rats. The PDR was absent in the youngest (5 day) and oldest (60 day) 6-OHDA treated rats but present with attenuated characteristics at around 15 and 20 days. The reappearance of the PDR in these rats closely paralleled age-related fluctuations in spinal cord noradrenaline (NE) which increased until 15 days, then precipitously declined, but did not correlate with spinal dopamine (DA) or serotonin (5-HT). The failure of the alpha noradrenergic blocking agents chlorpromazine, phenoxybenzamine, prazosin, or yohimbine to eliminate the vestigial PDR in the 15-20-day-old, 6-OHDA-treated rats indicates that this is probably not mediated by remaining, undamaged spinal NE neurons at this age. Neither is it likely to be mediated by spinal 5-HT neurons since inhibition of 5-HT synthesis had no effect upon the PDR latency in normal or neonatal 6-OHDA-treated, 17-day-old rats. In contrast to NE levels which increased with age in normal rats, spinal cord 5-HT and DA levels at least as high at 5 days of age as at adulthood.
D000375:Aging; D000818:Animals; D004298:Dopamine / Q000502:physiology; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology; D008125:Locus Coeruleus / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects; D018377:Neurotransmitter Agents / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000502:physiology*; D012701:Serotonin / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*
D006892:Hydroxydopamines; D018377:Neurotransmitter Agents; D012701:Serotonin; D016627:Oxidopamine; D004298:Dopamine; D009638:Norepinephrine