Hypoalgesia in response to sensitization during acute noise stress.
Three experiments examined the antinociceptive response shown by rats during exposure to loud noise. Noise exposure resulted in a time-dependent elevation of radiant heat tail flick latency that varied as a function of stimulus intensity. Noise stress hypoalgesia in response to a 90-dB stimulus was blocked by pretreatment with the opioid antagonist naltrexone (0.1-7.0 mg/kg). Systemic administration of midazolam (2 mg/kg) prior to exposure to the stressor attenuated the elevation in tail flick latency. Because topographically similar antinociceptive responses may be elicited with a low intensity noise stimulus that has served as a Pavlovian conditional stimulus for shock, the use of this paradigm may permit direct comparisons of associative and nonassociative fear responses using qualitatively similar auditory stimuli.
Helmstetter
F J
FJ
Department of Psychology, University of Wisconsin-Milwaukee 53201.
Bellgowan
P S
PS
D000161:Acoustic Stimulation; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D001288:Attention / Q000187:drug effects / Q000502:physiology; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D005239:Fear / Q000187:drug effects / Q000502:physiology; D008144:Loudness Perception / Q000187:drug effects / Q000502:physiology; D008297:Male; D008874:Midazolam / Q000494:pharmacology; D009271:Naltrexone / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D009622:Noise / Q000009:adverse effects*; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology; D013623:Tail / Q000294:innervation; D013697:Thermosensing / Q000187:drug effects / Q000502:physiology
D011957:Receptors, Opioid; D009271:Naltrexone; D008874:Midazolam