Stress－Indused Hypothermia Involves Stimulation of Adenosine A1－Receptors in Rats

Stress－Indused Hypothermia Involves Stimulation of Adenosine A1－Receptors in Rats

Creators Ushijima Itsuko

Creators Mizuki Yasushi

Creators Hara Takahide

Creators Soeda Koichiro

Creators Kudo Ryoji

Creators Miyoshi Akira

Creators Watanabe Katsumi

Creators Kajimura Naofumi

Creators Yamada Michio

Subcutaneous (s.c.) injection of adenosine produced hyperthermia in non-stressed rats and potentiated hypotermia in stressed rats. The potent adenosine A1-recepter stimulants, N6-cyclohexyl adenosine (CHA) and N6-(L-phenylisopropyl) adenosine (L-PIA) prodused hypothermia even in non-stressed rats, which was markedly potentiated in stressed trats. Futhermore, intracerbral ventricular (I.c.v.) injection of adenosine or adenosine analogues produced potentiation of stress-induced hypotermia relative to that induced with s.c.injection. N6-(D-phenylisoprophyl) adenosine (D-PIA) did not affect core temperature. When rats were treated with adenosine 1 h before atress, and then exposed to stress, the hyperthemia exhibited in the non-stressed state changed to hypothermia in the stressed state. When the rats which were treated with adenosine and then atressed for 1 h were released from stress, the hypothermia observed in the atressed state progressively changed to hyperthemia. Low doses of β-endorphin (I.c.v.) and morphine (s.c.)reversed stress-induced hypothermia which was potentiated by CHA, although high doses of β-endorphin (I.c.v.) and morphine (s.c.) potentiated the stress-induced hypothermia. These results suggest that the effects of adenosine on core temperature in rats are altered depending upon the state of animals. Stress-induced hypothermia may be, at least in part, mediated by endogenous adenosine which seems to selectively activate A1-receptor in the stressed state.

[ISSN]0513-1812

[NCID]AA00594272