Alternation of galanin in nociceptive modulation in the central nervous system of rats during morphine tolerance: a behavioral and immunohistochemical study.
The present study was performed to investigate the alternation of galanin in nociceptive modulation and galanin-like immunoreactivity in the central nervous system of rats after morphine tolerance. The hindpaw withdrawal latencies to both thermal and mechanical stimulation increased significantly after intracerebroventricular injection of 3 nmol of galanin in opioid-naive rats. The antinociceptive effect induced by galanin was attenuated remarkably at the same dose in morphine-tolerant rats. Furthermore, an up-regulation of galanin-like immunoreactivity in the arcuate nucleus of hypothalamus of morphine-tolerant rat was observed by immunohistochemical methods, whereas no significant changes were detected in periaqueductal gray. The present study demonstrated that there are alternations in both galanin-induced antinociception and galanin-like immunoreactivity in the brain of rat after morphine tolerance. The results suggest an involvement of galanin in the central nervous system in morphine tolerance.
Wu
Xia
X
Neurobiology Laboratory and National Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, PR China.
Yu
Long-Chuan
LC
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D002490:Central Nervous System / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D019004:Galanin / Q000008:administration & dosage / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D007276:Injections, Intraventricular / Q000379:methods; D008297:Male; D009021:Morphine Dependence / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology*; D010147:Pain Measurement / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D019004:Galanin