title: Acute stress regulates nociception and inflammatory response induced by bee venom in rats: possible mechanisms.
abstract: Restraint stress modulates pain and inflammation. The present study was designed to evaluate the effect of acute restraint stress on inflammatory pain induced by subcutaneous injection of bee venom (BV). First, we investigated the effect of 1 h restraint on the spontaneous paw-flinching reflex (SPFR), decrease in paw withdrawal mechanical threshold (PWMT) and increase in paw volume (PV) of the injected paw induced by BV. SPFR was measured immediately after BV injection, and PWMT and PV were measured 2 h before BV and 2-8 h after BV. The results showed that acute restraint inhibited significantly the SPFR but failed to affect mechanical hyperalgesia. In contrast, stress enhanced significantly inflammatory swelling of the injected paw. In a second series of experiments, the effects of pretreatment with capsaicin locally applied to the sciatic nerve, systemic 6-hydroxydopamine (6-OHDA), and systemic naloxone were examined on the antinociception and proinflammation produced by acute restraint stress. Local capsaicin pretreatment inhibited BV-induced nociception and inflammatory edema, and had additive effects with stress on nociception but reduced stress enhancement of edema. Systemic 6-OHDA treatment attenuated the proinflammatory effect of stress, but did not affect the antinociceptive effect. Systemic naloxone pretreatment eliminated the antinociceptive effect of stress, but did not affect proinflammation. Taken together, our data indicate that acute restraint stress contributes to antinociception via activating an endogenous opioid system, while sympathetic postganglionic fibers may contribute to enhanced inflammation in the BV pain model.
authors.affiliation: Department of Neurology, General Hospital of Shen-Yang Military Region, Shen Yang 110840, China. chszh@yahoo.com.cn
authors.forename: Hui-Sheng
authors.initials: HS
authors.lastname: Chen
authors.forename: Feng-Peng
authors.initials: FP
authors.lastname: Li
authors.forename: Xiao-Qiu
authors.initials: XQ
authors.lastname: Li
authors.forename: Bao-Jun
authors.initials: BJ
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Qu
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Wen
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Qing
authors.initials: Q
authors.lastname: Lin
mesh_terms: D000818:Animals; D001514:Bee Venoms / Q000009:adverse effects*; D002211:Capsaicin / Q000008:administration & dosage; D004195:Disease Models, Animal; D004487:Edema / Q000139:chemically induced / Q000473:pathology; D006614:Hindlimb / Q000187:drug effects; D006930:Hyperalgesia / Q000209:etiology* / Q000473:pathology; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology*; D008297:Male; D009270:Naloxone / Q000627:therapeutic use; D059225:Nociception / Q000502:physiology*; D016627:Oxidopamine / Q000627:therapeutic use; D010146:Pain / Q000139:chemically induced; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D012584:Sciatic Nerve / Q000187:drug effects; D013315:Stress, Psychological / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000502:physiology
chemical_list: D001514:Bee Venoms; D009270:Naloxone; D016627:Oxidopamine; D002211:Capsaicin