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...

in the present study, interactive effects of d1 and d2 dopamine receptors antagonists and different periods of lithium pretreatment on morphine dependence in mice have been investigated. this study was designed to investigate whether the hypothesis that lithium and dopaminergic mechanisms via their effects on phosphoinositide pathways and calcium flux could influence morphine withdrawal respons...

In the present study, interactive effects of D1 and D2 dopamine receptors antagonists and different periods of lithium pretreatment on morphine dependence in mice have been investigated. This study was designed to investigate whether the hypothesis that lithium and dopaminergic mechanisms via their effects on phosphoinositide pathways and calcium flux could influence morphine withdrawal respons...

In the present study, interactive effects of D1 and D2 dopamine receptors antagonists and different periods of lithium pretreatment on morphine dependence in mice have been investigated. This study was designed to investigate whether the hypothesis that lithium and dopaminergic mechanisms via their effects on phosphoinositide pathways and calcium flux could influence morphine withdrawal respons...

We have previously demonstrated that the antinociception induced by either endomorphin-1 or endomorphin-2 given supraspinally is mediated by the stimulation of mu-opioid receptors. However, the antinociception induced by endomorphin-2 given supraspinally contains additional components, which are mediated by the spinal release of dynorphin A (1-17) acting on kappa-opioid receptors and the spinal...

PURPOSE In nonocular systems, activation of opioid receptors has been shown to ameliorate tissue damage induced by ischemic stress. The current study was an investigation of whether opioid receptors activated by endogenous or exogenous agonists can ameliorate ischemic retinal injury. METHODS In an investigation of whether endogenous opioid receptor-activation reduces ischemic injury, the effe...

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, oxy...

Antagonistic properties of buprenorphine for and -opioid receptors were characterized in -endorphinand [D-Ala,NMe-Phe,Gly-ol]-enkephalin (DAMGO)-induced antinociception, respectively, with the tail-flick test in male ICR mice. -Opioid receptor agonist -endorphin (0.1–1 g), -opioid receptor agonist DAMGO (0.5–20 ng), or buprenorphine (0.1–20 g) administered i.c.v. dose dependently produced antin...

Opioid antagonists can be classified as inverse agonists and neutral antagonists. In the opioid-dependent state, neutral antagonists are significantly less potent in precipitating withdrawal than inverse agonists. Consequently, neutral opioid antagonists may offer advantages over inverse agonists in the management of opioid overdose. In this study, the relative potency of three opioid antagonis...

Intrathecal (i.t.) pretreatment with a low dose (0.3 nmol) of morphine causes an attenuation of i.t. morphine-produced analgesia; the phenomenon has been defined as morphine-induced antianalgesia. The opioid-produced analgesia was measured with the tail-flick (TF) test in male CD-1 mice. Intrathecal pretreatment with low dose (0.3 nmol) of morphine time dependently attenuated i.t. morphine-prod...