Sigma sites, originally proposed as opioid receptor subtypes, are currently thought to represent unique receptors with a specific pattern of drug selectivity, a well-established anatomical distribution and broad range of functional roles including potential involvement in nociceptive mechanisms. We have recently demonstrated that intrathecal (i.t.) treatment with a sigma-1 receptor antagonist r...

The cross-tolerance technique was used to analyze the receptor mechanisms of analgesia induced by electroacupuncture (EA) of 2 Hz, 100 Hz, or 2-15 Hz. (1) Rats were given EA stimulation of 2 Hz, 100 Hz and 2-15 Hz for 30 min with 30 min intervals successively. The percentage increase in tail-flick latency (TFL) was taken to indicate the intensity of EA analgesia. Rats made tolerant to repeated ...

The clinical usefulness of morphine for treatment of chronic pain is limited by development of tolerance. So many authors have proposed the co-administration of other drugs. This study was performed to evaluate the role of gabapentin on analgesic effect of morphine. Four groups of male rats (220-250 g) were examined for time latency using tail flick test: control, morphine (M), gabapentin (GB),...

In this study we used the chronic (formalin test) and acute (tail flick) pain models of rats for evaluation of probable analgesic and anti-inflammatory effect of Sambucus ebulus (Se) rhizome extract. Sodium salicylate (SS) was used as a positive control. A total of 300 mg/kg of SS (i.p.) had no effect on tail flick latency, while 100 and 200 mg/kg i.p. of extract increased this latency (P < 0.0...

In this study, we characterized the role of delta-1 and delta-2 opioid receptors in the ventromedial medulla (VMM) in the modulation of thermal nociception. Male Sprague-Dawley rats were prepared with an intracerebral guide cannula aimed at the nucleus raphe magnus or nucleus reticularis gigantocellularis pars alpha. Microinjection of the delta-1 opioid receptor agonist [D-Pen2,D-Pen5]enkephali...

Background.  Many mechanisms are involved in pain transmission in the spinal cord.  Therefore, combination of drugs acting on different kinds of mechanisms might be useful for analgesia.  We investigated the interaction betweenγ-aminobutyric acid （GABA）B receptor agonist, baclofen, and N-methyl-D-aspartate （NMDA） receptor antagonist, AP-5, orα-amino-3-hydroxy-5-methylisoxazole-4-propionic acid ...

In order to assess possible synergistic antinociceptive interactions, the analgesic effects of intra-peritoneal tramadol and morphine administered either separately or in combination were determined using tail-flick latency test following exposure to radiant heat in rats. Groups of eight male Sprague-Dawley rats received either tramadol (3.90, 7.00, 12.50, and 22.20 mg kg-1) and morp...

Ingestion of placenta and amniotic fluid has been shown to enhance opioid-mediated analgesia produced by morphine injection, footshock, vaginal/cervical stimulation, and during late pregnancy in rats. The present study was designed to determine how soon after ingestion the enhancement begins and how long it lasts. Tail-flick latencies in Long-Evans rats were determined before and during vaginal...

The clinical usefulness of morphine for treatment of chronic pain is limited by development of tolerance. So many authors have proposed the co-administration of other drugs. This study was performed to evaluate the role of gabapentin on analgesic effect of morphine. Four groups of male rats (220-250 g) were examined for time latency using tail flick test: control, morphine (M), gabapentin (GB),...