Suppression of paraquat-induced wet dog shakes by nitric oxide synthase inhibitors in rats.
We have found that paraquat (PQ), a widely used herbicide, causes wet dog shakes (WDS), which involve the central opioid system, in rats. A non-selective nitric oxide (NO) synthase (NOS) inhibitor, N(omega)-nitro-L-arginine (L-NA), but not its less active enantiomer, N(omega)-nitro-D-arginine, decreased the PQ-induced WDS in a dose-related manner. A selective neuronal NOS inhibitor in vivo, 7-nitroindazole, also decreased the PQ-induced WDS. Although an opioid receptor antagonist, naloxone, reversed the suppressive effect of these NOS inhibitors on the PQ-induced WDS, L-arginine, an NO precursor, had no effect on it. These findings suggest that the suppression of the PQ-induced WDS by NOS inhibition is associated with the central opioid system and is insusceptible to exogenous L-arginine.
Hara
S
S
Department of Forensic Medicine, Tokyo Medical University, Japan. s-hara@tokyo-med.ac.jp
Mukai
T
T
Kuriiwa
T
T
Yanase
T
T
Kurosaki
K
K
Kano
S
S
Endo
T
T
D000818:Animals; D001120:Arginine / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006540:Herbicides / Q000633:toxicity*; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D019335:Nitroarginine / Q000494:pharmacology; D010269:Paraquat / Q000037:antagonists & inhibitors* / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects*
D004791:Enzyme Inhibitors; D006540:Herbicides; D007191:Indazoles; D009292:Narcotic Antagonists; D019335:Nitroarginine; D009270:Naloxone; D001120:Arginine; D019001:Nitric Oxide Synthase; D010269:Paraquat; C080122:7-nitroindazole