Search PubMed⌕ Search

Biomedical subjects

I Creese

Publications and source records attributed to I Creese.

138 records · Page 8Linked to original sources
PubMed1975

The pharmacological and anatomical substrates of the amphetamine response in the rat.

Bilateral 6-hydroxydopamine microinjections into the substantia nigra abolished both the locomotor and stereotyped responses to d-amphetamine in adult rats. The lesions resulted in a depletion of over 99 per cent of striatal tyrosine hydroxylase activity (indicating a near total lesion of the nigro-striatal dopamine pathway) as well as severe noradrenaline depletions. However, lesion of the dorsal or ventral noradrenergic pathways resulted in similar noradrenaline depletions but with no effect on striatal tyrosine hydroxylase levels and without the concomitant blockage of the amphetamine response. The substantia nigra lesioned rats were behaviourally supersensitive to apomorphine and L-DOPA and did not show a locomotor response to cocaine. The substantia nigra lesioned rats were not aphagic or adipsic. It was concluded that both the locomotor and stereotyped responses induced by amphetamine are dependent on the functional integrity of the nigro-striatal dopamine pathway.

Animals↗
PubMed1975

Dopamine receptor binding in the corpus striatum of mammalian brain.

Specific binding of [3H]dopamine to membranes from the corpus striatum of rat and calf brain appears to involve the postsynaptic dopamine receptor. Specific [3H]dopamine binding is saturable, wnd with half-maximal binding in calf membranes at 7 nM. Apomorphine is about twice as potent as dopamine in competing for binding sites, whereas (-)norepinephrine is 5% as potent as dopamine and isoproterenol is virtually inactive. The relative potencies of phenothiazines as inhibitors of specific dopamine binding correlates with their clinical potencies and actions on the dopamine-sensitive adenylate cyclase.

Animals↗
PubMed1975

Receptor binding and pharmacological activity of opiates in the guinea-pig intestine.

A comparison was made between the affinities of a wide range of opiate agonists, mixed agonist-antagonists and antagonists for opiate receptor binding sites in the guniea-pig intestine longitudinal muscle and myenteric plexus preparation, and their pharmacological potency in influencing the electrically induced contraction of this in vitro functional system. The relative affinities of drugs and the degree of stereospecificity for intestinal binding sites are closely similar to these properties in the brain. Receptor binding correlates extremely well with pharmacological potency, both for agonists and antagonists, indicating that binding involves pharmacologically relevant opiate receptors. Pharmacological activity correlates best with receptor binding assayed in the presence of sodium.

Analgesics, Opioid↗
PubMedDate not supplied

Dopaminergic D-3 binding sites are not presynaptic autoreceptors.

Postsynaptic dopamine (DA) receptors have been classified biochemically and pharmacologically into two types: D-1 receptors mediate adenylate cyclase stimulation, demonstrating micromolar affinity for DA and butyrophenone antagonists; D-2 receptors mediate adenylate cyclase inhibition, demonstrating nanomolar affinity for DA and butyrophenone antagonists. D-1 receptors are labelled by 3H-thioxanthene antagonists, while D-2 receptors are labelled by both 3H-agonists and all 3H-antagonists. A third class of dopaminergic binding site, termed D-3, represents high-affinity 3H-agonist binding sites demonstrating low, micromolar, affinity for butyrophenones. In the rat striatum, D-3 sites were decreased 50% by 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal DA pathway, suggesting that such D-3 binding labels presynaptic DA autoreceptors on nigrostriatal terminals. However, nigrostriatal denervation produces a concomitant depletion of striatal DA. Here we demonstrate that a reserpine-induced depletion of DA produces a decrease in D-3 binding comparable to that seen with nigrostriatal denervation, independent of presynaptic terminal degeneration. This loss in binding, or that caused by 6-OHDA lesions, is recovered by preincubating the striatal membranes with DA or with the supernatant from control striatal membrane preparations. We therefore suggest that the loss of D-3 binding following 6-OHDA lesions results from the depletion of endogenous DA rather than the degeneration of terminals and their putatively associated autoreceptors.

Animals↗