Margit Szikszay

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Endomorphin-1 and endomorphin-2 were recently postulated to be endogenous mu-opioid receptor agonists. We have investigated the antinociceptive and antihyperalgesic effects of intrathecally administered endomorphins in cumulative doses (0.1-100 microg) on acute and inflammatory pain sensations in awake rats. In the tail-flick test, both peptides caused a(More)
Prolonged exposure to opioid agonists can induce adaptive changes resulting in tolerance and dependence. Here, rats were rendered tolerant by subcutaneous injections of increasing doses of morphine from 10 to 60 mg/kg for 3, 5, or 10 consecutive days. Binding parameters of the mu-opioid receptor in subcellular fractions were measured with [(3)H]DAMGO(More)
Agmatine, an endogenous ligand, interacts both with the alpha2-adrenoceptors and with the imidazoline binding sites. The effect of intrathecally administered agmatine on carrageenan-induced thermal hyperalgesia was investigated by means of a paw-withdrawal test in rats. The effect of agmatine on morphine-induced anti-hyperalgesia was also studied.(More)
Diltiazem, a calcium slow channel blocker, greatly potentiated and prolonged the antinociceptive effect of morphine in rats. Hypothermia, the primary thermoregulatory effect of morphine, was also potentiated. Verapamil, another calcium blocker elicited corresponding changes in the analgetic and thermoregulatory effects of morphine. These findings seem to be(More)
A comparison was made of the dose-effect relationship of intrathecally applied dexmedetomidine as concerns its mydriatic and antinociceptive effects in rats. Pupil diameter was measured with a photographic method without anesthesia. Antinociception was measured by means of the tail-withdrawal test. The intrathecal (i.t.) administration of dexmedetomidine(More)
Rats were subjected to prolonged footshock, intensive acoustic stress, cold water swim and restraint over a period of 10 days. The analgesic and thermoregulatory properties of morphine (2, 4 and 8 mg/kg, sc.) were tested on the 11th day. Analgesia assessment was performed by means of hot-plate (HP) and tail-flick (TF) tests, and body temperature (Tb)(More)
The hypothermic effect of capsaicin, the reduced responsiveness towards the hypothermic effect of the drug as well as the impairment of thermoregulation in a warm environment subsequent to the administration of different doses of capsaicin have been studied in rats. The mortality after capsaicin treatment has also been established. 1. Capsaicin given(More)
We describe a simple, noninvasive, nontraumatic, and reproducible ultrasonographic method to determine the effect of the alpha 2-adrenoceptor agonist dexmedetomidine in anesthetic dose (300 micrograms/kg subcutaneously) on the micturition reflex in intact rats. The bladder volumes were estimated by an ellipsoid equation. To validate the reliability of the(More)
A study was made of the effects of pretreatment with fractionated capsaicin on the changes in body temperature (Tb) induced in rats by exposure to cold and to warm environments, and by administration of histamine (40 mg·kg−1) or of pentobarbital (20 mg·kg−1) At the ambient temperature of 22 °C the Tb of capsaicin pretreated rats was lower than that of rats(More)
Our study examined whether calcium channels are involved in the anesthetic action of dexmedetomidine (100-300 micrograms/kg), a highly selective alpha 2-adrenoceptor agonist. To investigate this, we studied the effects of verapamil (1.25 or 2.5 mg/kg), a calcium channel blocker, and BAY K8644 (0.5 or 1 mg/kg), a calcium channel agonist, on the(More)