Pharmacology, biochemistry, and behavior
-
Pharmacol. Biochem. Behav. · Jan 2005
Comparative StudyKnock down of the alpha 5 nicotinic acetylcholine receptor in spinal nerve-ligated rats alleviates mechanical allodynia.
Nicotinic acetylcholine receptor (nAChR) agonists are known to alleviate neuropathic and inflammatory pain via activation of a heterogeneous population of receptors. However, the function of nAChRs in the maintenance of neuropathic pain is not known. Spinal nerve ligation (SNL) increases the spinal expression of the alpha5 nAChR subunit ipsilateral to injury. ⋯ Furthermore, using the phosphorylation of cAMP response element-binding protein (pCREB) as a general marker of neuronal activation, a significant increase in pCREB immunoreactivity was observed in SNL rats. Treatment of SNL rats with alpha5-antisense significantly reduced pCREB immunoreactivity. These results suggest that the increased expression of the alpha5 nAChR subunit following SNL contributes to spinal CREB phosphorylation and the maintenance of mechanical allodynia.
-
Pharmacol. Biochem. Behav. · Jan 2005
Comparative StudyInvolvement of potassium channels and nitric oxide in tramadol antinociception.
It has been considered that tramadol, a centrally acting analgesic, shows its effect via opiatergic, noradrenergic, and serotonergic systems. It has a low affinity for opioid receptors, and its effect can be partly blocked by naloxone. Since the noradrenergic and serotonergic mechanisms are still unknown, other systems which are associated with pain and analgesia may have a role on the antinociceptive effect of tramadol. ⋯ However, L-NAME augmented the antinociceptive effect of tramadol. The reduction of the effects of tramadol by L-arginine was reversed by L-NAME. The results of our study suggest that nonspecific voltage-dependent K+ channels and nitrergic system have a role on the antinociceptive effect of tramadol in mice hot plate test.
-
Pharmacol. Biochem. Behav. · Jan 2005
Comparative StudyComparison of five different rat models of peripheral nerve injury.
Described here is a comparison of five peripheral sciatic nerve injury models in rats which all result in various degrees of neuropathic pain symptoms. They are the chronic constriction injury (CCI), the spinal nerve ligation (SNL), the partial sciatic ligation (PSL), the tibial and sural transection (TST), and the complete sciatic transection (CST) model. ⋯ Overall, all five models of neuropathic pain produced signs of allodynia and hyperalgesia to various stimuli. However, the duration and magnitude of the evoked responses varied considerably between the different models.