Charles E. Rauh

Human brain receptor alterations in suicide victims

A comparison was made of human postmortem muscarinic-cholinergic, beta-adrenergic and serotonergic (presynaptic) recognition sites in cortical tissues derived from suicide and homicide (control) victims. An elevation of 47% and 35% in the suicide group compared to controls was observed in receptor ligand binding for 3H-quinuclidinyl benzilate (QNB, muscarinic antagonist) and 3H-imipramine (IMI, a presynaptic serotonin marker), respectively. In contrast, no appreciable differences in 3H-dihydroalprenolol (DHA, beta-adrenergic antagonist) binding were observed between the two groups. Additionally, tissues from both groups of subjects were analyzed for tricyclic antidepressive agent (TAD) content. High performance liquid chromatographic (HPLC) tissue analysis revealed no detectable levels of tricyclic agents with an assay sensitivity of 50 picograms/mg tissue. The results presented herein demonstrate neurotransmitter-receptor alterations in suicide subjects compared to homicide (control) victims. The attendant roles of serotonergic and muscarinic-cholinergic processes in the psychobiology of suicide and depression are addressed.

Neuropeptide Y stimulates inositol phospholipid hydrolysis in rat brain miniprisms

Neuropeptide Y (NPY) stimulates the hydrolysis of inositol phospholipid in rat brain miniprisms. The stimulation was two-fold in the frontal cortex and in the hippocampus, and 1.5-fold in the striatum. NPY produced no significant effects on basal inositol monophosphate levels in hypothalamic miniprisms. However, those basal levels were much higher than in the other brain regions.

3H-Spiroperidol binding to dopamine receptors in rat striatal membranes: influence of loxapine and its hydroxylated metabolites.

The effects of loxapine and its hydroxylated metabolites 7-hydroxyloxapine and 8-hydroxyloxapine on 3H-spiroperidol binding to rat striatal membranes were investigated. Whereas 7-hydroxyloxapine and loxapine displayed strong affinities for 3H-spiroperidol binding sites, 8-hydroxyloxapine was essentially inactive. The potency of 7-hydroxyloxapine to displace 3H-spiroperidol is 1.5 times and 8 times those of haloperidol and chlorpromazine, respectively. These results suggest that the combined effects of loxapine and 7-hydroxyloxapine on the postsynaptic dopamine receptors in the brain may explain the clinical efficacy of loxapine in the treatment of schizophrenia.

The anticonvulsant action of the carbonic anhydrase inhibitor methazolamide: Possible involvement of a noradrenergic mechanism

Abstract In contrast to previous concepts, the noradrenergic mechanism required for the anticonvulsant action of inhibitors of carbonic anhydrase in mice is extracerebral on the basis of the following: (1) the l-aromatic amino acid decarboxylase inhibitor Ro 4-4602/1 abolished the restorative action of d,1-dopa in reserpine- and phenoxy-benzamine-treated mice without evidence of significant inhibition of 1-aromatic amino acid decarboxylase in brain, (2) depletion of extracerebral stores of norepinehrine by the i.v. administration of 6-hydroxydopamine abolished the anticonvulsant effect of methazolamide, and (3) the anticonvulsant action of the carbonic anhydrase inhibitor in 6-hydroxydopamine-treated mice was restored by the administration of d,1-dopa. The noradrenergic mechanism appears to be of the α-type. Consistent antagonist action was shown by the α-blockers varied in action. The antagonist action of the α-blockers studied appeared to be specifically related to α-adrenergic blockade because (1) potency and duration of antagonist action correspond with potency and duration of α-adrenergic blockade, (2) phenoxybenzamine failed to antagonize the anticonvulsant action of diphenylhydantoin, (3) the anticonvulsant action of methazolamide was not abolished when phenoxybenzamine was given after the carbonic anhydrase inhibitor, (4) d,1-dopa administration reversed the antagonist action of phenoxybenzamine, and (5) the dopamine β-hydroxylase inhibitor U-14624 annulled the reversal of phenoxybenzamines antagonist action by d,1-dopa. The anticonvusant action of methazolamide in rats was not affected by depletion of cerebral or extracerebral stores of norepinephrine by 6-hydroxydopamine. Anticonvulsant action was abolished by the administration of reserpine to rats injected i.vent. with 6-hydroxydopamine. The data suggest that norepinephrine and serotonin both are involved in the anticonvulsant action of inhibitors of carbonic anhydrase in rats.

The intracellular localization of carbonic anhydrase and a carbonic anhydrase inhibitor in the brains of mice

Abstract Homogenates prepared from the perfused brains of mice were differentially centrifuged in 0.25 M sucrose. On the basis of activity per mg of nitrogen, only the supernatant showed a concentration of carbonic anhydrase activity greater than that of the original homogenate (about two- to three-fold). No concentration of activity was found in the particulate fraction, in any of its components studied, or in the washes of the various residues. Partition of per cent activity varied with the procedure used, but approximately two-thirds of the total activity of the original homogenate were in the supernatant fraction; the total particulate matter accounted for about one-third. No differences of any consequence were found amongst whole brain, cortex, and brain with the cortex removed. The data are believed to demonstrate the intracellular localization of carbonic anhydrase in the soluble fraction of cells; the activity of particulate matter is considered to be the result of contamination. The inhibitor of carbonic anhydrase found in the brains of mice following the intravenous administration of methazolamide was almost entirely localized in the supernatant fractions; an intercellular localization in the soluble fraction is also postulated. The localization of both carbonic anhydrase and carbonic anhydrase inhibitor in the soluble fraction of homogenates of the brains of mice does not constitute evidence of the inhibition of the enzyme in the brain in vivo . However, the concentrations of inhibitor found in the whole homogenates 15 min and 2 hr after the administration of doses of methazolamide at the level of the ED 95 for anticonvulsant effect were theoretically capable of causing maximum inhibition of carbonic anhydrase in the brains of mice. Anticonvulsant action and inhibition of carbonic anhydrase are probably related.

Assay of brain calmodulin levels using high-performance liquid chromatography.

Abstract: A simple, sensitive, and efficient HPLC method for the determination of calmodulin levels in brain tissue extracts is described. The assay is linear with respect to both calmodulin and protein concentrations. The specificity and validity of this assay for calmodulin is demonstrated by parallel radioimmunoassay determinations which give equivalent results. Determination of calmodulin levels in various brain regions revealed a high concentration of this protein in the hypothalamus, by comparison to other areas examined.

The effects of acute administration of diazepam on the binding of [3H]-diazepam and [3H]-GABA to rat cortical membranes

Specific [3H]-diazepam binding and [3H]-GABA binding were measured in cortical membranes of untreated rats and rats which had been administered unlabeled diazepam (5.0 mg/kg, IP) thirty minutes prior to sacrifice. Washed and unwashed membranes from control animals showed identical levels of [3H]-diazepam binding. Unwashed membranes of diazepam-treated animals showed consistently and significantly lower binding of [3H]-diazepam than membranes derived from control animals and treated similarly. [3H]-GABA was almost non-existent in unwashed membranes of either group of animals. The binding capability of membranes of treated animals for [3H]-diazepam returned to control levels upon washing with buffer prior to the binding assay. The specific binding of [3H]-GABA in membranes derived from either group of animals also improved after the buffer washes. However, no difference could be detected in [3H]-GABA binding between control and diazepam-treated animals. The failure of diazepam to modulate [3H]-GABA binding in unwashed membranes and the participation of an endogenous inhibitory material repressing [3H]-GABA binding are discussed.

Method for the measurement of respiration in unanesthetized rats: Effect of selected analgesics and hypnotics

Summary An apparatus and procedure for the measurement of minute volume and respiratory rate in the unanesthetized rat has been described. A change of ±10% or greater from pretreatment minute volume indicates a significant ( P P At equal analgesic dosages, morphine was shown to be quantitatively more depressant to respiration than meperidine or codeine. Sodium phenobarbital was shown to exert a more sustained respiratory depression than methyprylon at a dose producing a comparable degree of locomotor ataxia. Nalorphine administered alone was found to exhibit a moderate respiratory depressant effect regardless of the dosage used, but when given in conjunction with either morphine, meperidine, or codeine a dose-dependent antagonism was observed.

Striatally-mediated response of some structurally rigid analogues of dopamine

The potency of structurally rigid analogues of dopamine (DA) at striatal dopamine receptors was evaluated in rats using three types of assessments: (a) effectiveness in producing rotational and sniffing behaviors by intrastriatal injections (b) inhibition of [3H]-spiroperidol binding and (c) stimulation of adenylate cyclase activity. The compounds included apomorphine (APO) and its analogues, (R)-2,10,11-trihydroxyaporphine (R-THA) and (R)-2-hydroxy-10,11-methylenedioxyaporphine (MDO-APO), 2-amino-6,7-dihydroxyaminotetraline (ADTN) and its analogue, exo-2-amino-6,7-dihydroxybenzonorbornene (exo-amine). (R)-THA produced no stereotypy yet it was a potent inhibitor of [3H]-spiroperidol binding and adenylate cyclase activity. MDO-APO was quite active in inducing stereotypy and stimulating cyclase activity, but it showed low potency in displacing [3H]-spiroperidol. The exo-amine and ADTN were equally potent in enhancing rotation and sniffing intensity, however, the former was completely inactive in biochemical assessments. Except for (R)-THA, all DA analogues studied elicited dopaminomimetic behavioral activities of circling and sniffing. Relationships between the actions of these drugs in the behavioral and biochemical assessments are discussed.