Histaminergic influence on vestibular stimulation-induced locus coeruleus inhibition in rats.
In previous reports we have shown that caloric stimulation (CS) of the vestibular apparatus inhibits locus coeruleus (LC)-noradrenergic neuronal activity in urethane-anaesthetized rats. The present study examined the effect of neural histamine depletion by alpha-fluoromethylhistidine (alpha-FMH) on CS-induced LC inhibition. In alpha-FMH treated rats, LC neuronal inhibition caused by CS was still observed. This finding indicates that the central histaminergic neuron system does not participate in the CS-induced LC-noradrenergic inhibition. It is suggested that the noradrenergic neuron system is involved in the development of vestibulo-autonomic response, independent of the histaminergic neuron system.
Nishiike
S
S
Department of Otolaryngology, Osaka University Medical School, Japan.
Takeda
N
N
Uno
A
A
Kubo
T
T
Yamatodani
A
A
Nakamura
S
S
D000818:Animals; D017776:Autonomic Pathways / Q000187:drug effects / Q000502:physiology*; D002150:Caloric Tests / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006632:Histamine / Q000032:analysis / Q000502:physiology*; D006640:Histidine Decarboxylase / Q000037:antagonists & inhibitors; D006358:Hot Temperature; D008125:Locus Coeruleus / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014722:Vestibule, Labyrinth / Q000502:physiology
D004791:Enzyme Inhibitors; D008762:Methylhistidines; C028309:alpha-fluoromethylhistidine; D006632:Histamine; D006640:Histidine Decarboxylase