naloxone and crocin

In this study, the effects of intraperitoneal (i.p.) injection of crocin in the absence and presence of subcutaneous (s.c.) injections of morphine and naloxone were investigated on the formalin test in rats. The formalin test was induced by intra-plantar (i.pl.) injection of formalin (50 microL, 1%), and the time spent licking and biting of the injected paw was measured for 1 h. Formalin induced a marked biphasic (first phase: 0-5 min and second phase: 15-45 min) pain response. Morphine (1 mg/kg, s.c.) significantly (p < 0.05) suppressed both phases of pain. Naloxone (2 mg/kg, s.c.) alone did not change the intensity of pain, but pretreatment with naloxone (2 mg/kg) significantly (p < 0.05) prevented morphine (1 mg/kg)-induced antinociception. Crocin at doses of 50, 100 and 200 mg/kg significantly (p < 0.05) attenuated pain. Crocin (100 mg/kg, i.p.) significantly (p < 0.05) increased the morphine (1 mg/kg, s.c.)-induced antinociception. Naloxone (2 mg/kg) did not reverse the suppressive effect of crocin (100 mg/kg) on pain. Crocin at a dose of 400 mg/kg significantly (p < 0.05) suppressed locomotor activities. These findings indicate that morphine through a naloxone-sensitive mechanism produced analgesia. Crocin produced a dose-dependent antinociceptive effect. In addition, crocin increased morphine-induced antinociception, but naloxone did not change the antinociceptive effect of crocin.

Topics: Analgesia; Analgesics, Opioid; Animals; Carotenoids; Male; Morphine; Motor Activity; Naloxone; Pain; Pain Measurement; Rats; Rats, Wistar

Crocus sativus L. has been shown to interact with the opioid system. Thus, the effects of aqueous and ethanolic extracts of stigma and its constituents were evaluated on morphine-withdrawal syndrome in mice. Dependence was induced using subcutaneous (s.c.) injections of morphine for 3 days. On day 4, morphine was injected 0.5 h prior the interaperitoneal (i.p.) injections of the extracts, crocin, safranal, clonidine (0.3 mg/kg) or normal saline. Naloxone was injected (5 mg/kg i.p.) 2 h after the final dose of morphine and the number of episodes of jumping during 30 mm was considered as the intensity of the withdrawal syndrome. Clonidine, the aqueous and ethanolic extracts of saffron reduced the jumping activity. Safranal was injected (s.c.) 30 mm prior and 1 and 2 h after the injection of morphine. It potentiated some signs of withdrawal syndrome. The aqueous extract decreased the movement in all of the doses (80, 160, 320 mg/kg) and the ethanolic extract decreased it in the dose of 800 mg/kg in open field test. But crocin and the dose of 400 mg/kg ethanolic extract showed no effect on activity in this test. It is concluded that the extracts and crocin may have interaction with the opioid system to reduce withdrawal syndrome.

Topics: Animals; Carotenoids; Clonidine; Crocus; Cyclohexenes; Male; Mice; Morphine; Morphine Dependence; Motor Activity; Naloxone; Plant Extracts; Substance Withdrawal Syndrome; Terpenes

In this study, the effects of intraperitoneal (i.p.) and intracerebroventricular (i.c.v.) injection of crocin in separate and combined treatments with i.p. injections of morphine (an opioid receptor agonist) and naloxone (an opioid receptor antagonist) were investigated on acute corneal pain in rats. Acute corneal pain was induced by local application of a drop of 5 M NaCl solution on the corneal surface. The number of eye wipes was taken as a pain response, and counted during the first 30 s. Crocin injected i.p. and i.c.v. and morphine injected i.p. significantly (p < 0.05) decreased the number of eye wipes. Morphine (i.p.)-induced antinociception was significantly (p < 0.05) increased by the systemically and centrally injected crocin. The antinociceptive effects induced by i.p. and i.c.v. injections of crocin were not reversed by i.p. injection of naloxone. These findings indicated that both crocin and morphine attenuated hypertonic saline-induced corneal pain. The opioid receptors may not be involved in the analgesic mechanism of crocin.

Topics: Analgesics, Opioid; Animals; Carotenoids; Cornea; Drug Combinations; Injections, Intraperitoneal; Injections, Intraventricular; Male; Morphine; Naloxone; Pain; Pain Measurement; Rats; Rats, Wistar