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J Barchas

Publications and source records attributed to J Barchas.

At least 19 recordsLinked to original sources
PubMed1983

Measurement of total opioid peptides in rat brain and pituitary by radioimmunoassay directed at the alpha-N-acetyl derivative.

A sensitive assay, which cross-reacts with and is specific for diverse opioid peptides, is described. This is based on the prior acetylation of samples and subsequent radioimmunoassay with an antiserum highly specific for the acetylated NH2 terminus of opioid peptides. The result is a procedure that can be used to investigate multiple forms of opioid peptides in extracts of biological material. The sensitivity of the assay is approximately 15 fmol of beta-endorphin per incubation tube, i.e., approximately 100-fold greater sensitivity than the radioreceptor assay used in our laboratory. The peptide concentration required for 50% displacement of trace ranged from 0.65 nM (beta-endorphin) to 1.6 nM (Met-enkephalin). The assay apparently shows an absolute requirement for a free (or acetylated) NH2 terminus corresponding to either a Leu- or Met-enkephalin sequence. Use of the assay with and without prior acetylation of sample provides a method for estimation of the ratio of acetylated:nonacetylated opioid peptides in crude or fractionated extracts. The procedure is used to investigate the forms of opioid peptide found in rat brain and pituitary.

Acetylation↗
PubMed1983

Reciprocal day/night relationship between serotonin oxidation and N-acetylation products in the rat pineal gland.

Pineal tryptophan, serotonin [5-hydroxytryptamine (5-HT)], N-acetylserotonin, melatonin, 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 5-methoxytryptophol, and 5-methoxyindoleacetic acid were measured by high pressure liquid chromatography with electrochemical detection. A complete analysis required less than the equivalent of two rat pineal glands. Samples were obtained at eight time points. A reciprocal physiological relationship was found between oxidation and N-acetylation products of 5-HT. 5-HT and the oxidation products 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 5-methoxytryptophol, and 5-methoxyindoleacetic acid decreased at night, when the N-acetylation products N-acetylserotonin and melatonin increased. These observations are consistent with the hypothesis that circadian changes in the N-acetylation of 5-HT by indoleamine N-acetyltransferase is the major factor controlling circadian changes in the amounts of 5-HT, and 5-HT oxidation and N-acetylation products in the rat pineal gland.

Acetylation↗
PubMed1978

Methylxanthine-facilitated shock-induced aggression in the rat.

The methylxanthines caffeine and aminophylline, in daily doses of 100 mg/kg, facilitated shock-induced aggression in the rat. Under the limited parameters of this study, there was no induction of mouse-killing behavior or alteration of jump thresholds. Additional studies showed the optimal dose and time course for the facilitation of shock-induced aggression by caffeine to be 50 mg/kg administered i.p. 4 h prior to testing. Facilitation of a central adrenergic system may be the mechanism of action.

Aggression↗
PubMed1977

Alkali metal cations: effects on isolation-induced aggression in the mouse.

Alkali metal cations were given in varying doses over 14 days to CF-1, male mice, isolated for 4 weeks prior to testing for isolation-induced fighting. Lithium and cesium in doses of 4.5 and 6.0 meq/kg reduced the duration of isolation-induced aggression in a 15 min test period when compared with controls. Toxicity was evident in the cesium-treated, but not the lithium-treated mice. No enhancement of aggression was seen in the rubidium-treated group.

Aggression↗