Differences between the Lewis and Sprague-Dawley rats in chronic inflammation induced norepinephrine sensitivity of cutaneous C-fiber nociceptors.
We investigated whether there are any differences between the Lewis and Sprague-Dawley (SD) rats in chronic inflammation-induced norepinephrine (NE) sensitivity of nociceptors. Activities of C-fiber nociceptors innervating rat hairy hindpaw skin were recorded in an in vitro skin-nerve preparation. Sixty-five percent of C-fibers from inflamed Lewis rats were excited by NE (10 microM), against only 38% of C-fibers from inflamed SD rats. The average of the total impulses evoked in response to NE was also significantly higher in Lewis rats. The alpha2-adrenoceptor antagonist CH 38083 (10 microM) and yohimbine (10 microM) consistently blocked the NE-excitation of both strains. These results show that after chronic inflammation, C-fiber nociceptors of Lewis strain rats have a stronger sensitivity to NE, and that alpha2-adrenoceptors are predominately involved in the NE-sensitivity of inflamed rats in both strains.
Banik
R K
RK
Department of Neural Regulation, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan.
Sato
J
J
Yajima
H
H
Mizumura
K
K
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002908:Chronic Disease; D005620:Freund's Adjuvant / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000187:drug effects / Q000503:physiopathology; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology*; D009412:Nerve Fibers / Q000187:drug effects* / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011917:Rats, Inbred Lew / Q000502:physiology*; D017207:Rats, Sprague-Dawley / Q000502:physiology*; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects / Q000378:metabolism; D012867:Skin / Q000187:drug effects / Q000294:innervation; D017779:Sympathetic Fibers, Postganglionic / Q000503:physiopathology; D013566:Sympathomimetics / Q000494:pharmacology*
D018341:Receptors, Adrenergic, alpha-2; D013566:Sympathomimetics; D005620:Freund's Adjuvant; D009638:Norepinephrine