Pharmacology & toxicology
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Pharmacology & toxicology · Aug 2001
ReviewAspects on the pathophysiology of migraine and cluster headache.
The specific cause of migraine headache remains unknown. Current theories suggest that the initiation of a migraine attack involves a primary CNS dysfunction with subsequent activation of the trigeminovascular system. ⋯ Triptan administration, activating the 5-HT(1B/1D) receptors, caused the headache to subside and the neuropeptide release to normalise. These data suggest the involvement of sensory and parasympathetic mechanisms in the pathophysiology of primary headaches.
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Pharmacology & toxicology · Aug 2001
GABA mechanisms and antinociception in mice with ligated sciatic nerve.
In the present study, the effects of GABA (gamma-aminobutyric acid) receptor agonists and antagonists on hyperalgesia induced by sciatic nerve ligation was investigated in mice. The response to morphine or GABA receptor agonists was examined 14 days after unilateral nerve ligation by hot-plate test. Intraperitoneal injection of different doses of morphine (3, 6 and 9 mg/kg), muscimol (0.5, 1 and 2 mg/kg) or baclofen (1, 2.5 and 5 mg/kg) induced a dose-related antinociception in both intact and ligated mice. ⋯ However, morphine in combination with muscimol (2 mg/kg) tends to induce higher response; the combination of the GABA receptor agonists with morphine did not show potentiation, but additive effect. The opioid receptor antagonist naloxone reduced the response induced by muscimol in nerve-ligated animals. It was concluded that although ligation of the sciatic nerve clearly reduced the analgesic effect of morphine and not that of the GABA agonists, the results nevertheless indicated that morphine and the GABA(A) agonist shared the same mechanism of action.