Recent neuroanatomical and behavioral evidence has indicated that vasopressin (VA) increases pain threshold. The dorsal raphe nucleus (DRN) is an important nucleus in pain modulation. Anatomical studies have shown that DRN receives vasopressinergic fibers originating in the hypothalamic paraventricular nucleus. The aim of the present study was to examine the effects of intra-DRN injection of de...

The current study has investigated the involvement of periaqueductal gray (PAG) metabotropic glutamate subtype 7 and 8 receptors (mGluR(7) and mGluR(8)) in modulating rostral ventromedial medulla (RVM) ongoing and tail flick-related on and off cell activities. Our study has also investigated the role of PAG mGluR(7) on thermoceptive threshold and PAG glutamate and GABA release. Intra-ventrolate...

The leaves of Mitragyna speciosa were chewed as a substitute to opium in Thailand and Malaysia. A study was therefore undertaken to compare the antinociceptive activity of morphine and paracetamol to that of mitragynine, a major constituent of fresh leaves of M. speciosa. The tests employed were acetic acid induced writhings, hot tail-flick and cold tail flick. All test drugs were administered ...

bulbospinal noradrenergic pathways are shown to have an important role in descending inhibition of pain sensation. locus ceruleus (lc), as a rich noradrenergic nucleus in the brain stem which has projections into the dorsal horn of the spinal cord, was evaluated for antinociceptive activity by using tonic and phasic pain models in the rat. lc-lesioned rats demonstrated moderate increase in both...

This study investigated the antinociceptive mechanisms of khat extract (100, 200, and 400 mg/kg, i.p.) in four pain models: two thermic (hot plate, tail-flick) and two chemical (acetic acid, formalin) models. Male mice were pretreated intraperitoneally (i.p.) with the opioid receptor blocker naloxone (5 mg/kg), the cholinergic antagonist atropine (2 mg/kg), the selective α1 blocker prazosin (1 ...

The present study aims to investigate the analgesic activity of the methanol extract of the galls of Quercus infectoria in rats using hot plate and tail-flick methods. The extract was administered intraperitoneally at a dose of 20 mg/kg while morphine sulfate and sodium salicylate (10 mg/kg) served as standards. The methanol extract exhibited significant analgesic activity in the tail-flick mod...

The effects of the tricyclic antidepressants desipramine HCI and chlorimipramine HCI on buprenorphine HCI antinociceptive activity were studied in mice using the hot-plate and the tail-flick methods. In the hot-plate test, desipramine caused a transient antinociceptive effect at low doses, but it decreased buprenorphine analgesia. Chlorimipramine in this test caused a more sustained antinocicep...

Recent neuroanatomical and behavioral evidence has indicated that vasopressin (VA) increases pain threshold. The dorsal raphe nucleus (DRN) is an important nucleus in pain modulation. Anatomical studies have shown that DRN receives vasopressinergic fibers originating in the hypothalamic paraventricular nucleus. The aim of the present study was to examine the effects of intra-DRN injection of de...