The role of neuronal nitric oxide synthase on hypobaric hypoxia-induced antinociception in writhing test.
It has been reported that hypobaric hypoxia exposure by high altitude is responsible for neuropsychological impairment. In the present study, we examined an effect of hypobaric hypoxia on the writhing test. The ICR mice were exposed in hypobaric chamber with several altitudes (5000, 10,000 or 20,000 ft) for 1 or 2 h, and then immediately injected intraperitoneally (i.p.) with 1% acetic acid for writhing test. Our results show that both 10,000 ft and 20,000 ft exposure induce antinociceptive effect in writhing test, but 5,000 ft does not. In addition, this antinociceptive effect was abolished by L-NAME (nitric oxide synthase inhibitor) pre-treated intraperitoneally, but not naloxone (non-specific opioid receptor antagonist). Furthermore, we examined that neuronal NOS immunoreactivities in the hypothalamus (paraventricular nucleus and arcuate nucleus) were increased by hypobaric hypoxic exposure (10,000ft). These results suggest that hypobaric hypoxic-induced antinociception may be associated with neuronal NOS IR in the hypothalamus.
Choi
Seung-Min
SM
Department of Pharmacology, Institute of Natural Medicine, Hallym University, ChunCheon, Korea.
Chung
Soo-Young
SY
Seol
Chang-Ahn
CA
Sul
Jin-Gon
JG
Kwon
Min-Soo
MS
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000201:enzymology*; D000860:Hypoxia / Q000201:enzymology* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D052248:Nitric Oxide Synthase Type I / Q000502:physiology*; D010147:Pain Measurement / Q000379:methods*; D010286:Paraventricular Hypothalamic Nucleus / Q000201:enzymology*; D011897:Random Allocation
D052248:Nitric Oxide Synthase Type I