Naunyn-Schmiedeberg's archives of pharmacology
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Naunyn Schmiedebergs Arch. Pharmacol. · May 1993
Prevention and reversal of motor and sensory peripheral nerve conduction abnormalities in streptozotocin-diabetic rats by the prostacyclin analogue iloprost.
The effects of the prostacyclin analogue iloprost on nerve function were examined in streptozotocin-diabetic rats. Rats were treated either with iloprost from induction of diabetes over 2 months in a preventive experiment, or for 1 month following a 1 month untreated period of diabetes in a reversal experiment. One and 2 months untreated diabetic control, non-diabetic control, and iloprost-treated non-diabetic groups were also used. ⋯ Iloprost treatment significantly attenuated this for both preventive (47%, P < 0.001) and reversal (50%, P < 0.001) studies. There was no effect on hypoxic resistance for non-diabetic rats. In the preventive group there was a 28% increase in sciatic nerve endoneurial capillary density (P < 0.001), a lesser effect (16%, P < 0.05) in the reversal group, and no effect in non-diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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Naunyn Schmiedebergs Arch. Pharmacol. · May 1993
Role of dopamine receptors in the dual effect of naloxone on quinpirole-induced yawning in morphine pretreated rats.
The present study was undertaken to determine the state of sensitivity of dopamine D2/D3 receptors involved in the mediation of yawning behaviour at various times following acute morphine administration to rats. Morphine (3.0 mg/kg, s.c.) induced a biphasic effect on locomotor activity: an initial inhibitory phase lasting for about 30 min was after about an hour followed by a phase of locomotor activation lasting for about 60 min. Dopamine D2/D3 receptor agonist quinpirole (0.01-0.1 mg/kg, s.c.) induced yawning behaviour in rats. ⋯ D1 receptor antagonist SCH 23390 [R-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3- benzazepin-7-ol hemimaleate] at 0.01 mg/kg did not affect quinpirole-induced yawning or its inhibition by morphine. However, in rats which received morphine 90 min prior to testing yawning, SCH 23390 enhanced quinpirole-induced yawning behaviour as compared with morphine- or saline-pretreated animals. The data obtained in the present study indicate that morphine pretreatment initially induces a lack of responsiveness of the D2/D3 receptors mediating yawning behaviour and subsequently increases their sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)