Effects of intracerebroventricular administration of N-acetylhistamine on body temperature in mice.
The purpose of this study was to examine the effects of intracerebroventricular (i.c.v.) administration of N-acetylhistamine on rectal temperature, histamine level, histidine decarboxylase (HDC) activity, and the turnover rate of monoamines in mice. More than 60 micrograms of N-acetylhistamine induced hypothermia. The maximum effect of hypothermia was observed 20 min after administration of N-acetylhistamine (60-120 micrograms/mouse). A significant drop in rectal temperature of 3 degrees C was induced by 120 micrograms of N-acetylhistamine. Concurrent with the appearance of hypothermia, the histamine levels were increased. However, both histamine H1 and H2 antagonists did not prevent hypothermia. The i.c.v. administration of N-acetylhistamine inhibited HDC activity, but had no effect on the turnover rates of monoamines. These data confirmed that endogenous N-acetylhistamine may be a metabolite which lacks significant physiological roles, and demonstrated that exogenous N-acetylhistamine is not a good pharmacological tool for the study of the functions of the brain histaminergic system in mammals.
Onodera
K
K
Department of Pharmacology, Tohoku University School of Dentistry, Sendai, Japan.
Shinoda
H
H
Imaizumi
M
M
Hiraki-Sakurai
E
E
Yamatodani
A
A
D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism; D001831:Body Temperature / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects; D006632:Histamine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D006640:Histidine Decarboxylase / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains
D015306:Biogenic Monoamines; C021606:N-acetylhistamine; D006632:Histamine; D006640:Histidine Decarboxylase