Implication of ATP-sensitive K+ channels in various stress-induced analgesia (SIA) in mice.
Exposure to footshock (2 mA, 1-sec duration, 0.2 Hz for 15 min; FS), forced swimming (water at 20 degrees C for 3 min, SW) or psychological stress (using a communication box for 5 min, PSY) produced antinociceptive effects (stress-induced analgesia, SIA). Intracerebroventricular (i.c.v.) injection of glibenclamide (10-40 micrograms/mouse), an ATP-sensitive K+ (KATP) channel blocker, antagonized FS-SIA, while SW- and PSY-SIA were unaffected by the compound. Cromakalim (0.1-10 micrograms/mouse, i.c.v.), a KATP-channel opener, did not affect FS-, SW- or PSY-SIA. Thus, we provided evidence that central KATP channels participate in the production of FS-SIA but not production of SW- or PSY-SIA; and we suggest that glibenclamide, through closing of KATP channels, suppresses mu-opioid receptor functions, which subsequently leads to the inhibition of FS-SIA since antinociception is produced by the activation of mu-receptors.
Nakao
K
K
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Nagasaki University, Japan.
Takahashi
M
M
Kaneto
H
H
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000698:Analgesia; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D019806:Cromakalim; D005905:Glyburide / Q000494:pharmacology; D008297:Male; D051379:Mice; D015221:Potassium Channels / Q000502:physiology*; D011758:Pyrroles / Q000494:pharmacology; D013312:Stress, Physiological / Q000503:physiopathology*
D001578:Benzopyrans; D015221:Potassium Channels; D011758:Pyrroles; D019806:Cromakalim; D000255:Adenosine Triphosphate; D005905:Glyburide