Articles: hyperalgesia.
-
Some abdominal pain syndromes are characterized by persistent pain without demonstrable pathology. Many of them are prevalent in women and it is known that sex hormones are associated with differences in pain perception between males and females. To model a process of functional abdominal pain in females we studied the time course and estrogen dependency of a hyperalgesic state induced by ovariectomy in adult mice. ⋯ In another series of experiments a slow release pellet containing 17beta-estradiol was implanted in half of the OVX mice and a similar pellet without the hormone in the other half. Hormone replacement prevented the development of hyperalgesia in OVX animals but did not stop the involution of the internal reproductive organs. We conclude that OVX in mice provides a useful model for a hormonally dependent hyperalgesic state resembling functional pain.
-
In neuropathic rats sensitive to phentolamine (alpha-adrenoreceptor antagonist, 2 mg/kg, i.p.), prazosin (alpha1-adrenoreceptor antagonist, 0.5 mg/kg, i.p.) significantly attenuated cold allodynia whereas yohimbine (alpha2-adrenoreceptor antagonist, 0.5 mg/kg, i.p.) had no significant effect. In neuropathic rats insensitive to phentolamine, yohimbine significantly exacerbated cold allodynia whereas prazosin had no significant effect. These results suggest that the individual differences in the sensitivity of cold allodynia to phentolamine may be due to the difference in the alpha-adrenoreceptor subtype predominantly involved in cold allodynia.
-
J. Neurosci. Methods · Oct 2005
Characterization of a model of cutaneous inflammatory pain produced by an ultraviolet irradiation-evoked sterile injury in the rat.
Neuroimmune interactions are of known importance in the genesis and maintenance of inflammatory pain states. However, the immune response to tissue damage is likely to differ depending on whether or not the injury is accompanied by infection. Many clinically important inflammatory pain states involve a sterile tissue injury. ⋯ The animals develop heat-hyperalgesia, mechano-hyperalgesia, mechano-allodynia, and cold-allodynia that last for several days. Cold-allodynia appears within 6 h or less, but the other symptoms are not clearly evident until 12-36 h after exposure. This model offers several advantages for the experimental analysis of the causes of inflammatory allodynia and hyperalgesia.
-
Neuroscience letters · Oct 2005
Intracisternal administration of mitogen-activated protein kinase inhibitors reduced IL-1beta-induced mirror-image mechanical allodynia in the orofacial area of rats.
The present study investigated the role of central mitogen-activated protein kinases (MAPKs) in interleukin-1beta (IL-1beta)-induced mirror-image mechanical allodynia in the orofacial area. Experiments were carried out on Sprague-Dawley rats. Under pentobarbital sodium anesthesia, a polyethylene tube was implanted in the subcutaneous area of one vibrissa pad, which enabled us to inject IL-1beta. ⋯ Intracisternal pretreatment with PD98059, a p44/42 MAPK inhibitor, or SB203580, a p38 MAPK inhibitor, significantly reduced the decrease in the threshold of air puffs ipsilateral to the IL-1beta injection site produced by 10 pg of IL-1beta. IL-1beta-induced mirror-image mechanical allodynia was also reduced significantly by intracisternal pretreatment with both PD98059 and SB203580. These results indicate that central MAPK pathways mediate IL-1beta-induced mirror-image mechanical allodynia in the orofacial area.