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Biomedical subjects

D A Longman

Publications and source records attributed to D A Longman.

8 recordsLinked to original sources
PubMed1982

Effects of intrapallidal drugs on hyperactivity induced by nucleus accumbens dopamine receptor stimulation.

The effect of manipulating globus pallidus (GP) transmitters on the locomotor hyperactivity induced by administration of the dopamine agonist ADTN in the nucleus accumbens was investigated in rats with permanent intracerebral cannulae. Hyperactivity was antagonized by the GABA agonists muscimol and baclofen and the GABA antagonist bicuculline. Atropine, ADTN and ethylketazocine in GP had no effects on the response. Both morphine and the 5-HT agonist 5-methoxy-N,N-dimethyltryptamine prevented the hyperactivity. The findings emphasize the role of GP GABA in the NA-induced hyperactivity and provide information about the functions of some other GP transmitters.

Animals↗
PubMed1982

A method for measuring drug-induced changes in limb muscle tone in the rat.

A method for measuring the time-course and magnitude of changes in rat hind leg muscle tone in vivo is described in detail. The rat is held in a restraining box and the apparatus pushes each hindpaw from behind a distance of 1 cm and measures the force required to briefly hold each leg in the displaced position. The push-relax cycle is repeated every 45 s. Identical measurements were obtained from the 2 hind legs. Experimental results are presented to demonstrate the potential of the technique for investigating the effects of drugs on muscle tone. Morphine, which is known to cause rigidity, increased the force required to displace the hind legs. Muscle tone was reduced in rats that were lightly anaesthetized.

Animals↗
PubMed1980

An in vivo method for testing putative GABA-like compounds.

A technique is described that enables compounds with GABA-ergic properties to be rapidly identified in vivo. Electrical stimulation of the neostriatum in the conscious rat evoked a contralateral head-turn. Evidence is presented that this easily timed motor response involves, at least in part, GABA-ergic mechanisms in the globus pallidus. GABA drugs were injected through a cannula into the ipsilateral globus pallidus and their effects on head-turning observed. Known GABA agonists including muscimol slowed the head-turn, whereas the GABA antagonist picrotoxin facilitated it. A number of drugs such as baclofen, diazepam, and pentobarbitone which have been attributed with GABA-like properties behaved like GABA agonists in the head-turn model following either intrapallidal or intraperitoneal injection. Other drugs, e.g. tranquillizers, with no known GABA-like properties, did not effect the head-turn time.

Animals↗