The authors investigated the analgesic effects of small morphine doses injected into the paraventricular nucleus (PVN) of normal rats and hypophysectomized (Hx) rats. An injection cannula was stereotactically inserted into the PVN or third ventricle. On the 5-7th postoperative day, morphine (7 micrograms) was injected and the pain threshold (paw lick latency: PLL) was measured using a hot plate...

Opioids are considered a "gold standard" in clinical practice for the treatment of postoperative pain. The spinal administration of an opioid drug does not guarantee selective action and segmental analgesia in the spine. Evidence from experimental studies in animals indicates that bioavailability in the spinal cord biophase is negatively correlated with liposolubility, and is higher for hydroph...

The authors conducted a randomized, prospective study comparing epidural morphine with patient-controlled intravenous (iv) morphine in 30 patients recovering from total hip or total knee arthroplasty. Six, 18, and 24 hr postoperatively, patients used a 10 cm visual-analogue scale to indicate both their current degree of discomfort and the maximum discomfort they had experienced since the previo...

Morphine is a well-known mu-opioid receptor (MOR) agonist and an efficient analgesic, but its long-term use inevitably leads to drug addiction and tolerance. Here, we show that specific inhibition of beta-arrestin2 with its siRNA lentivirus microinjected in mice periaqueductal gray matter (PAG) significantly improved both acute and chronic morphine analgesia and delayed the tolerance in the hot...

  In this study, the effects of lead acetate on two types of pain (nociception and inflammation) induced by formalin and its interaction with the opioid system and morphine-induced analgesia were examined. Male albino mice weighing 22-27 g were used in the experiments. Morphine was administered subcutaneously 30 minutes before formalin injection. Lead acetate was intraperitoneally administered ...

Previous studies have shown that the extract of Papaver rhoeas reduces morphine dependence, locomotor activity and reward. In present study, the effects of hydro-alcohol extract of Papaver Rhoeas on the tolerance to analgesic effects of morphine in mice have been investigated using tail flick method. Subcutaneous (s.c.) administration of morphine (1, 2, 5 and 10 mg/kg) induced analgesia. Howeve...

Previous studies have shown that the extract of Papaver rhoeas reduces morphine dependence, locomotor activity and reward. In present study, the effects of hydro-alcohol extract of Papaver Rhoeas on the tolerance to analgesic effects of morphine in mice have been investigated using tail flick method. Subcutaneous (s.c.) administration of morphine (1, 2, 5 and 10 mg/kg) induced analgesia. Howeve...

UNLABELLED Sex differences in pain perception and in response to opioids have been described, but the findings are inconsistent. We sought to determine the effect of sex on pain perception, morphine consumption, and morphine analgesia after surgery. We designed a prospective cohort study and included 423 women and 277 men who emerged from general anesthesia after surgical procedures and who rep...

Introduction: Several researches have reported that stress is able to inhibit the development of morphine tolerance via activating of Hypothalamic-Pituitary-Adrenal (HPA) axis. In the present study we tried to examine the effect of epinephrine, the product of adrenal medulla, on the development of morphine tolerance. Methods: Analgesic tolerance was induced by intrathecal (i.t.) injection of...

Pain is one of the most distressing post-operative consequences of surgeries. Opioids have been the mainstay in providing pain relief. Morphine is the considered to be the “gold standard” amongst opioids as an analgesic. Nalbuphine, a synthetic opioid agonist/antagonist has analgesic potency almost equivalent to that of morphine on a milligram basis and fewer complications like respiratory depr...