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Biomedical subjects

M Stanley

Publications and source records attributed to M Stanley.

At least 145 records · Page 8Linked to original sources
PubMed1984

Adverse effects of single therapeutic doses of diazepam on performance in normal geriatric subjects: relationship to plasma concentrations.

Elderly normal volunteers (N = 12, mean age 70.4 years) were administered placebo or diazepam 2.5, 5, 10 mg in four consecutive sessions separated by at least a 1-week interval. Memory and psychomotor performance and plasma diazepam concentrations were assessed at baseline and at 1 and 3 h following drug administration. Significant impairments were found in response to all doses of diazepam. The maximum impairment occurred at 1 h, which coincided with the highest plasma concentration of the drug.

Aged↗
PubMed1984

Enhancement of memory by a cholinesterase inhibitor associated with muscarinic receptor down-regulation.

Rats trained on a passive avoidance task 24 hours following a single intraperitoneal injection of diisopropyl fluorophosphate (DFP, 1.2 mg/kg) showed enhanced retention when tested 7 days later. In a parallel group of rats, reduced cortical [3H] quinuclidinyl benzilate binding was demonstrable 24 hours following DFP administration. The association of reduced muscarinic receptor binding and enhanced performance on a memory task contradicts previous reports which suggested that retention was impaired by treatments which down-regulate muscarinic receptors. This contradiction may be reconciled if pre-synaptic factors such as agonist availability are considered in conjunction with post-synaptic receptor effects.

Analysis of Variance↗
PubMed1984

Postmortem and regional changes of serotonin, 5-hydroxyindoleacetic acid, and tryptophan in brain.

Using a specific and sensitive high pressure liquid chromatographic technique for the measurement of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), and tryptophan (TRP), we found that there were no changes in 5-HT or 5-HIAA in the rat cortex when left in situ for 6 h at room temperature or 24 h at 4 degrees C. Only a minimal 14% increase in 5-HT was observed after 24 h at 4 degrees C in the striatum of the same animals. Concentrations of TRP, however, were increased significantly in both brain regions by these postmortem delay procedures. A second study revealed that there were significant regional 5-HT and 5-HIAA concentration differences within the cerebral cortex. The frontal cortex was shown to have the highest concentrations of 5-HT and 5-HIAA. Further, within the frontal cortex, 5-HIAA levels varied, showing apparent progressive rostral to caudal increases. 5-HT concentrations, however, remained constant within the frontal cortex. These results are discussed in reference to the conflicting reports of the previous human suicide and postmortem studies.

Animals↗
PubMed1984

Postmortem monoamine oxidase enzyme kinetics in the frontal cortex of suicide victims and controls.

Serotonin, a preferred monoamine oxidase (MAO) A substrate may be deficient centrally in suicide victims. In postmortem samples of frontal cortex from suicide victims we demonstrated receptor changes in the serotonergic system supportive of this hypothesis. These changes were not accompanied in this series of brain samples by alterations in either MAO A or B enzyme kinetics. Thus brain MAO A is not a useful indicator of altered serotonergic function in suicide victims. We did confirm an age-related increase in cortical MAO B but not MAO A enzyme concentrations in both controls and suicide victims.

Adult↗
PubMed1984

Cholinergic receptor binding in the frontal cortex of suicide victims.

Muscarinic binding sites were assessed in the frontal cortex of 22 suicide victims and 22 control subjects. There were no significant differences between the two groups in either the number of binding sites (Bmax) or their relative affinity (Kd). The results of this study are discussed in reference to the cholinergic hypothesis of affective disorders.

Adolescent↗
PubMed1983

Attenuation of pilocarpine-induced hypothermia in response to chronic administration of choline.

Chronic treatment of rats with choline caused a decrease in the hypothermic response to pilocarpine. The action of choline on the muscarinic receptors is consistent with electrophysiological and binding studies, supporting a direct muscarinic action for choline. Administration of direct muscarinic agonists has been shown to cause a decrease in the number of muscarinic receptors. Thus, the long-term use of cholinergic precursors could have some adverse effects on central cholinergic functioning.

Animals↗
PubMed1983

Modulating role of lithium on dopamine turnover, prolactin release, and behavioral supersensitivity following haloperidol and reserpine.

The effects of haloperidol, reserpine, and concomitant lithium were evaluated in biochemical, endocrine, and behavioral studies in the rat. Concomitant administration of a chronic regimen of haloperidol and lithium did not prevent the development of tolerance as noted by dopamine metabolites in the striatum or olfactory tuberculum. Nor did chronic lithium alter behavioral response in rats treated with reserpine and challenged with the dopamine agonist apomorphine. Additionally, prolactin release was increased by haloperidol, but was not altered by acute or chronic lithium treatment. These findings are discussed in the light of present knowledge of pre- and postsynaptic receptor changes and the effects of lithium.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1983

Lack of potency of metoclopramide's metabolites in various dopaminergic models.

The dopaminergic properties of metoclopramide and four of its metabolites were determined in a series of in vivo and in vitro tests. In vivo measures included changes in dopamine turnover, serum prolactin levels and antagonism of apomorphine-induced stereotyped behavior. In each of these tests the four metabolites were either completely inactive or significantly less potent than the parent compound. The potency of metoclopramide and its metabolites in in vitro dopamine/neuroleptic receptor models was compared to the potency of standard reference compounds. In vitro results indicate that none of the four metabolites tested had antagonist activity in any of the receptor models in which they were evaluated. These findings will be discussed in light of the current understanding of receptor models as they relate to antipsychotic efficacy.

Animals↗
PubMed1983

Aging and cortisol resistance to suppression by dexamethasone: a positive correlation.

Cortisol resistance to suppression by 0.5 mg of dexamethasone given at 11 p.m. was studied in 30 normal subjects, 17 to 78 years of age. Serum cortisol concentrations were determined by radioimmunoassay. A strong positive correlation was found between age and cortisol concentrations 9 hours after dexamethasone administration. The data suggest that aging, per se, might contribute to the increased cortisol resistance to suppression by dexamethasone reported in depression and dementia.

Adolescent↗
PubMed1983

Effect of electroconvulsive shock on muscarinic cholinergic receptors in rat cerebral cortex and hippocampus.

Single electroconvulsive shock (ECS) induced no change in [3H]quinuclidinyl benzilate ([3H]QNB) binding to muscarinic cholinergic receptors in rat cortex and hippocampus. ECS administered once daily for 7 days induced a significant reduction in [3H]QNB binding in both brain areas. Concurrent ECS reversed the significant increase in cortical [3H]QNB binding induced by chronic atropine administration. These findings may have relevance to the antidepressant or amnestic effects of electroconvulsive therapy.

Animals↗
PubMed1983

Central catecholamine metabolism in vivo and the cognitive and motor deficits in Parkinson's disease.

Cerebrospinal fluid levels of homovanillic acid (HVA) in unmedicated patients with Parkinson's disease were 45% of levels in control subjects. Levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) and platelet monoamine oxidase activity (MAO) did not differ. Within the Parkinson's disease group platelet MAO B activity correlated with HVA (an MAO B substrate) but not MHPG (an MAO A substrate). A mild global dementia was found that did not correlate with the more severe motor deficit. There was a negative correlation between the motor deficit and HVA levels but not with MHPG. Cognitive functioning correlated positively with platelet MAO, and the ratio of HVA to MHPG levels and negatively with MHPG alone. It is postulated that dopaminergic and noradrenergic activity or the functional balance between these systems may contribute to the observed cognitive dysfunction.

Blood Platelets↗
PubMed1983

Glycine: a possible role in lithium's action and affective illness.

In addition to its incorporation into proteins, glycine functions as both a regulator of one-carbon metabolism and as an inhibitory neurotransmitter. Clinical recognition of the hyperglycinemias and reported elevations of erythrocyte glycine concentrations in patients with bipolar disorders have implicated this amino acid in the etiopathology of some neuropsychiatric disorders. Moreover, chronic lithium administration, an almost specific intervention for the treatment and prophylaxis of bipolar disorders, has been shown to induce elevations in brain and erythrocyte glycine levels. In view of glycine's complex metabolic interrelationships and neurotransmitter function, additional research exploring its possible role in either affective illness or lithium's action is indicated.

Amino Acid Metabolism, Inborn Errors↗