The functional interactions between supraspinal p, and 8 receptors were characterized in the mouse using p, receptor-selective antagonists. The effects of pretreatment with the p, opioid antagonists, /~-funaltrexamine (/'/-FNA) and naloxonazine on the modulation of morphine antinociception by the 8 agonists [D-PenZ,D-PenS]enkephalin (DPI)PE) and [D-AlaZ,MetS]enkephalinamide (DAMA) were studied....

Roles of endogenous opioid peptides and their receptors in modulation of the nocifensive responses to formalin in mice were studied. Mice were pretreated i.c.v. or intrathecally (i.t.) with selective opioid receptor antagonists or intrathecally with antisera against endogenous opioid peptides and the nocifensive licking responses to intraplantar injection of formalin (0.5%, 25 microl) were then...

Morphine was used as a remedy for the control of diarrhea centuries before it's sedative-analgesic effect was discovered. Although several mechanisms have been proposed for the morphine-induced inhibition of gastrointestinal transit (OIT), the exact mechanism has not yet been identified. On this basis the possible involvement of the dopaminergic system in morphine-induced inhibition of tra...

The effects of pretreatment with endomorphin-1 (EM-1) and endomorphin-2 (EM-2) given into the ventral periaqueductal gray (vPAG) to induce antianalgesia against the tail-flick (TF) inhibition produced by morphine given into the vPAG were studied in rats. Pretreatment with EM-1 (3.5-28 nmol) given into vPAG for 45 min dose-dependently attenuated the TF inhibition produced by morphine (9 nmol) gi...

ziziphora tenuior has been used in iranian folk medicine as an analgesic and for treament of digestive diseases.this study was designed to investigate the antinociceptive effects of hydroalcoholic extract of z. tenuior on visceral pain and its possible involvement in opioidergic and serotoninergic systems in male albino n-mri mice. antinociceptive effect of was determined by writhing test as a ...

We have previously demonstrated that both endomorphin-1 (EM-1) and endomorphin-2 (EM-2) at high doses (1.75-35 nmol) given intrathecally (i.t.) or intracerebroventricularly produce antinociception by stimulation of mu-opioid receptors. Now, we report that EM-2 at small doses (0.05-1.75 nmol), which injected alone did not produce antinociception, produces anti-analgesia against opioid agonist-in...

The present study investigated the effects of intra-dentate gyrus microinjection of naloxone (an opioid antagonist) and thioperamide (an antagonist of histamine H3 receptors) in the formalin test in rats. Subcutaneous injection of formalin (50 μl, 2.5 %) in the ventral surface of right hind paw produced a biphasic pattern (first phase: 0-5 min and second phase: 15 - 60 min) of licking/biting an...

the role of opioid receptor and voltage dependent calcium channels on the kindling induced by the convulsant pentylenetetrazole (ptz) were investigated in the rats. experiment involved 24 rats which were divided into four groups. kindling was established with ptz in subconvulsive dose (37.5 mg/kg i.p.) every 48 h and effects were observed within 20 min using five-point scoring system. all anima...

The antinociception induced by i.t. or i.c.v. administration of endomorphins is mediated via mu-opioid receptors. However, although endomorphins do not have an appreciable affinity for kappa-opioid receptors, pretreatment with the kappa-opioid receptor antagonist norbinaltorphimine markedly reduces the antinociceptive response to i.c.v. or i.t. administered endomorphin-2 but not endomorphin-1. ...

introduction: oxytocin is a active neuropeptide of central nervous system. in this study the effects of naloxone (opioid receptor antagonist) and yohimbine (α-2 adrenergic receptor antagonist) on analgesic effect of oxytocin applied into the locus coeruleus (lc) nucleus were investigated. methods: adult male wistar rats were used. animals divided into different groups receiving saline, oxytocin...