Margit Szikszay

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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)
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)
  • Margit Szikszay, F. Obál, F. Obál
  • 1982
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)
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)
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)
BACKGROUND The spinal administration of some N-methyl-d-aspartate receptor antagonists results in antinociception and potentiates the effects of opioids and alpha2-adrenoceptor agonists, but ketamine and its enantiomers have not been examined. The present study investigated the interactions of racemic ketamine, R(-)-ketamine and S(+)-ketamine with morphine(More)
UNLABELLED Ketamine exerts antinociceptive effects in many pain tests. We investigated the antinociceptive effect of intrathecally administered racemic ketamine and its S(+)- and R(-)-enantiomer on carrageenan-induced thermal hyperalgesia with a paw withdrawal test and acute pain (hot plate and tailflick) tests. Rats were prepared with a chronic lumbar(More)
Morphine was provided to rats in drinking water for 21 days. Profound analgesic tolerance was detected both in hot-plate and tail-flick tests. The density of [3H]DAMGO binding sites increased by 76% in spinal cord membranes due to morphine exposure compared to those in opioid naive animals. Slightly augmented [3H]DAMGO binding was measured in the synaptic(More)
The purpose of this study was to assess the effects of calcium channel antagonist, verapamil, and agonist, Bay K 8644, on the alpha 2-adrenoceptor agonist, dexmedetomidine-induced (300 micrograms kg-1 subcutaneously) diuresis and overflow incontinence, in rats. Ultrasonography study revealed that verapamil (2.5 mg kg-1 subcutaneously) or Bay K 8644 (0.5 mg(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)