in the present study, the effect of gaba (γ-aminobutyric acid) receptor agonists and antagonists on morphine-induced antinociception was investigated in formalin test in rats. intraperitoneal (i.p.) injection of different doses of morphine (1, 3, 6 and 9 mg/kg) and intracerebroventricular (i.c.v.) injection of different doses of muscimol (0.5, 1 and 2 g/rat) or baclofen (0.25, 0.5 and 1 g/rat) ...

Fentanyl has been shown to be a potent analgesic with a lower propensity to produce tolerance and physical dependence in the clinical setting. The present study was designed to investigate the mechanisms of fentanylor morphine-induced antinociception at both supraspinal and spinal sites. In the mouse tail-flick test, the antinociceptive effects induced by both fentanyl and morphine were blocked...

The postictal state is generally followed by antinociception. It is known that connections between the dorsal raphe nucleus, the periaqueductal gray matter, and the locus coeruleus, an important noradrenergic brainstem nucleus, are involved in the descending control of ascending nociceptive pathways. The aim of the present study was to determine whether noradrenergic mechanisms in the locus coe...

Previous studies have shown that systemic administration of 6'-hydroxy-2',4'-dimethoxychalcone (flavokawin B, FKB) exerts significant peripheral and central antinociceptive effects in laboratory animals. However, the mechanisms underlying these peripheral and central antinociceptive effects have yet to be elucidated. Therefore, the objective of the present study was to evaluate the participatio...

Exposure to stressful or fear-inducing environmental stimuli activates descending antinociceptive systems resulting in a decreased pain response to peripheral noxious stimuli. Stimulating mu opioid receptors in the basolateral nucleus of the amygdala (BLA) in anesthetized rats produces antinociception that is similar to environmentally induced antinociception in awake rats. Recent evidence sugg...

Substantial evidence has been accumulated which suggests that opioid delta receptors may be distinguished on the basis of their involvement in the modulation (i.e., increase or decrease in potency) of mu-mediated antinociception. On this basis, it has been hypothesized that some opioid delta receptors exist within a functional complex with mu receptors (delta complexed (delta cx) receptors) whi...

The present study was conducted on rats with inflammation induced by subcutaneous injection of carrageenan into the left hindpaw. Intrathecal administration of oxytocin produced dose-dependent increases in the hindpaw withdrawal latency (HWL) to thermal and mechanical stimulation in rats with inflammation. The antinociceptive effect of oxytocin was blocked by intrathecal administration of atosi...

BACKGROUND Opioid analgesics are effective in relieving chronic pain, but they have serious adverse effects, including development of tolerance and dependence. Ibudilast, an inhibitor of glial activation and cyclic nucleotide phosphodiesterases, has shown potential in the treatment of neuropathic pain and opioid withdrawal. Because glial cell activation could also be involved in the development...

the amygdala is a forebrain region, which is known as a modulator of pain sensation. the amygdala, particularly the central nucleus, has high concentrations of enkephalins relative to dynorphins and has high concentrations of opioid receptors. we here studied the role of central nuclei of amygdala in morphine antinociception. methods: in this study, we used 130 male wistar rats (200- 250g). bil...

In the present study the effects of both CCK receptor agonists and antagonists on antinociception induced by morphine in the tail-flick test have been evaluated. M orphine induced dose-dependent antinociception in mice. The response of morphine was potentiated by sulfated cholecystokinin-8 (CCK-8S) but not by unsulfated cholecystokinin-8 (CCK-8U). The CCK receptor antagonists MK-329 and L-...