Learn More
Kelatorphan, an inhibitor of the enkephalin-degrading enzymes, infused by microdialysis (10(-6) M) in the striatum of anaesthetized rats, significantly increased dopamine (DA) output but left dihydroxyphenylacetic acid and homovanillic acid extracellular levels unchanged. The local application of naltrexone (10(-6) M) prevented the effect of kelatorphan on(More)
The present study investigated the role of mu and delta opioid receptors in the control of the horizontal and vertical components of locomotion. Mice received intracerebroventricularly (i.c.v.) enkephalin analogs specific for either the mu or delta opioid receptors. The administration of the specific mu agonist [D-Ala2-NMePhe4-Gly5(ol)] enkephalin (DAGO)(More)
The present study investigated the effects of a striatal lesion induced by kainic acid on the striatal modulation of dopamine (DA) release by mu- and delta-opioid peptides. The effects of [D-Pen2,D-Pen5]-enkephalin (DPDPE) and [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAGO), two highly selective delta- and mu-opioid agonists, respectively, were studied by(More)
In the hot plate test, the dopamine D2 receptor agonist RU 24926 as well as the mixed dopamine D1/D2 receptor agonist apomorphine dose dependently increased the nociceptive threshold of mice, as expressed by the jump latency. The dopamine D1 receptor agonist SKF 38393 was ineffective on this parameter. The effect of RU 24926 was antagonized by the dopamine(More)
In the present study we report the effects of inhibitors of enkephalin-degrading peptidases on spontaneous locomotion in mice and the involvement of delta opioid receptors in these effects. Animals received intracerebroventricularly (i.c.v.) or intravenously (i.v.) enkephalinase inhibitors (thiorphan and acetorphan), aminopeptidase inhibitors (bestatin and(More)
The enkephalinase inhibitor thiorphan was infused intracerebroventricularly in rats during 14 days (25 micrograms/5 microliters/hr), inducing an average inhibition of cerebral enkephalinase of about 65%. Animals were tested during the infusion for their response to acetorphan, a parenterally active derivative of thiorphan. When administered intravenously on(More)
Acetorphan, a parenterally active enkephalinase inhibitor, induced dose-dependently a naloxone-reversible analgesia on the hot-plate jump test in DBA/2J (DBA2) mice but was devoid of effects in C57BL/6J (C57) mice. By contrast, acetorphan increased locomotion in both strains; however, the DBA2 strain was much more sensitive than C57 mice to the locomotor(More)
In several pain models, tricyclic antidepressants (TCAs) have been shown to reduce nociception. In the present study, we evaluated the antinociceptive effect of metapramine (META) in 4 nociception tests: (1) the hot plate test; (2) the phenylbenzoquinone-induced writhing; (3) the tail flick test; and (4) the test of electrical stimulation of the tail. We(More)
Acetorphan, an enkephalinase inhibitor, or morphine was injected in mice which had received saline or morphine (32 mg/kg s.c. twice a day on 8 consecutive days) chronically. In the hot-plate test, the analgesia (increase in jump latency) induced by morphine (2 mg/kg i.p.) or by the mu selective opioid agonist, [D-Ala2,N-Me-Phe4, Gly5-ol]enkephalin (DAGO)(More)
In mice, rendered poikilothermic by a prior (18 hr) subcutaneous administration of reserpine (3 mg/kg), the subcutaneous administration of apomorphine increased dose-dependently the body temperature. This effect was potentiated by the specific D2 dopamine antagonist sulpiride. On the contrary, it was reduced by the specific D1 dopamine antagonist SCH 23390.(More)