Current models of endogenous pain control circuitry emphasize neural substrates within the brainstem and spinal cord. We have recently shown, however, that the central nucleus of the amygdala (Ce) contributes to morphine-induced suppression of formalin-induced nociceptive behaviors. In the four experiments reported here, we investigated the possibility that the Ce also contributes to morphine-i...

Purpose: In this study, we evaluated the analgesic potential of demethylating drugs on oral cancer pain. Althoughdemethylating drugs could affect expressionofmany genes,we focused on themu-opioid receptor (OPRM1) gene pathway, because of its role in pain processing. We determined the antinociceptive effect of OPRM1 re-expression in a mouse oral cancer model. Experimental Design: Using a mouse o...

Epibatidine, a neurotoxin isolated from the skin of Epipedobates tricolor, is an efficacious antinociceptive agent with a potency 200 times that of morphine. The toxicity of epibatidine, because of its nonspecificity for both peripheral and central nicotinic receptors, precludes its development as an analgesic. During the synthesis of epibatidine analogs we developed potent antinociceptive agen...

The role of the acetylcholine-mediated system in the organization of postictal antinociception was investigated. For this purpose, nicotinic and muscarinic cholinergic receptor antagonists were microinjected into the nucleus raphe magnus (NRM), a key structure of the endogenous pain inhibitory system. After the tail-flick test baseline recording, male Wistar rats (N=8 per group) were submitted ...

Pain associated-anxiety induced by formalin, which resulted in a significant delay in the development of tolerance to morphine antinociception, failed to prevent the development of physical dependence as evidenced by naloxone challenge. Dependence also developed in mice rendered tolerant to morphine. Thus, the development of morphine dependence was observed in the absence and presence of tolera...

The present study focused on the evaluation of a role of opioid system in nicotine-induced antinociception and physical dependence in mice. The results indicate that nicotine (3 mg/kg) produced a significant antinociception in the hot plate test. Additionally, the opioid receptor antagonist naloxone (0.5 and 1 mg/kg), dose-dependently attenuated this effect. Our second experimental protocol con...

In the present study, effects of intracerebroventricular (icv) administration of histamine, mepyramine (H1-receptor antagonist) and famotidine (H2-receptor antagonist) have been investigated on the formalin test in rats. Subcutaneous injection of formalin (50 microl, 1%) into the ventral surface of the left hind paw produced a marked biphasic pain response (first phase: 0-5 min and second phase...

Metoclopramide, a prokinetic drug, has been documented to produce antinociceptive response in animal models through opioid pathways. Morphine has been shown to act through ATP sensitive potassium channels (KATP) to produce antinociceptive response. However, such a possibility has not been examined for metoclopramide. The present study investigated this using pharmacological tools. Acetic acid i...

The effects of caerulin, a CCK receptor agonist, and proglumide, a receptor antagonist, on hyperalgesia induced by sciatic nerve ligation, was studied in mice. Tolerance to the morphine response was obtained 3,7, 14,21 and 28 days after unilateral sciatic nerve ligation. Maximum hyperalgesia was found 14 days after nerve ligation. Caerulin increased morphine antinociception in nerve-ligated ani...

objective: vitex agnus-castus (vac) and its essential oil have been traditionally used to treat many conditions and symptoms such as premenstrual problems, mastalgia, inflammation, sexual dysfunction, and pain. in this study, the effects of essential oil extracted from vitex agnus-castus (eovac) leaves were investigated in three behavioral models of nociception in adult male wistar rats. materi...