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Biomedical subjects

S N Pradhan

Publications and source records attributed to S N Pradhan.

At least 55 records · Page 3Linked to original sources
PubMed1976

Temporal and regional differences in brain concentrations of lithium in rats.

Lithium (Li) concentrations have been estimated in several peripheral tissues (serum, heart, kidney, liver and skeletal muscle) and different brain areas (cortex, caudate nucleus, hypothalamus, diencephalon, midbrain, pons-medulla and cerebellum) at different intervals (0.5 to 48 h) after administrations of 3 mEq/kg of lithium chloride (LiCl). The Li concentrations in the brain areas increased gradually, reaching their peak at 8 h; the hypothalamus showed the highest concentration measured between 0.5 and 8 h; after 8 h the highest concentration was observed in the caudate nucleus, followed approximately by those of the cortex, rest of the diencephalon, and other areas. Concentration of Li in the skeletal muscle, although initially less, was maintained at a higher percentage of the initial level for more than 24 h compared to the other peripheral tissues.

Animals↗
PubMed1976

Carcinogenicity of Camellia sinensis (tea) and some tannin-containing folk medicinal herbs administered subcutaneously in rats.

In an attempt to correlate the high incidence of esophageal carcinoma in natives of certain places with their habit of using herbaceous folk medicines, we performed bioassays of several plant extracts and the fractions prepared from them. Fourteen extracts and fractions from 6 plants were injected sc into NIH Black rats. The tannin fractions from Quercus falcata pagodaefolia, Diospyros virginiana, and Camellia sinensis were very active and produced tumors at the injection site in 66% or more of the treated animals. Tannin fractions from 3 other plants and total aqueous extracts from 5 to 6 tested plants were also tumorigenic rats. The induced tumors were malignant fibrous histiocytomas similar, if not identical, to those encountered in humans. The experiment indicated a possibility of induction of tumor in man by the tested plant materials.

Animals↗
PubMed1976

Effects of sound stimulus on gastric secretion and plasma corticosterone level in rats.

The effects of sound stimulus were studied on the gastric secretion in rats with chronically implanted cannulas. Attempts were made to correlate the changes in the secretion with those of the plasma corticosterone level. Exposure of the animals to sound stimulus (1 hr or 2 hr) produced a marked decrease in gastric secretion and a concomitant increase in plasma corticosterone. It appears that in producing these effects sound stimulus acted as a stressor. Furthermore, a paradoxical increase in secretion was noted in the first hour collection prior to the sound stimulus. This initial increase in secretion may be due to an adaptive compensatory mechanism in anticipation of its marked inhibition.

Acoustic Stimulation↗
PubMed1976

Effects of lithium on foot shock-induced aggressive behavior in rats.

The effects of lithium chloride (LiC1; 1, 2, 3 mEq/kg, i.p.) were studied on foot shock-induced aggressive behavior categorized as 'hyperreactivity' 'pre-attack' and actual 'fight' or 'attack' scores in rats. The attack score was significantly decreased at all doses between 2 to 48 hr post-drug intervals. LiCl also antagonized both amphetamine-induced facilitation and scopolamine-induced suppression of the shock-induced aggression; these effects suggest a probable role of lithium in normalizing induced disturbances of both central adrenergic and cholinergic mechanisms and may at least partly be responsible for its psychotherapeutic efficacy as a "mood normalizer".

Aggression↗
PubMed1975

Cardiovascular effects of central microinjections of apomorphin in cats.

Microinjections of apomorphine (25-300 mug) were made into the lateral ventricle, dorsal nucleus of the vagus and ventromedial nucleus of the hypothalamus of cats through a stereotaxically implanted cannula-electrode. Apomorphine caused depressor and bradycardic effects without any dose-response relationship. At the above doses of apomorphine the efferent vagal discharges werr markedly increased concurrent with cardiovascular changes. Respiration was not affected except at higher doses causing depression in some experiments. Pretreatment with atropine, scopolamine or haloperidol abolished those responses. Similar results were observed with bivagotomy and midcollicular transection. Dopamine (125-100 mug), acetylcholine (10-100 mug) and norepinephrine (25-100 mug) caused similar cardiovascular changes, as in the case of apomorphine, and such effects were blocked by both specific and non-specific autonomic blackers. Thus the hypothalamus and the dorsal nucleus of the vagus appear to be inbolved in the central cardiovascular effects of apomorphine and such effects may be mediated through more than one neurotransmitter mechanisms.

Acetylcholine↗
PubMed1975

Interactions of adrenergic stimulants and blockers on self-stimulation behavior in rats.

Self-stimulation behavior in rats was facilitated by two adrenergic stimulants, amphetamine (0.5 or 1 mg/kg, intraperitoneal, i.p., or 100 mug, intracerebroventricular, i.c.v.) and cocaine (5 mg/kg, i.p.). Three alpha-adrenergic blockers (phenoxybenzamine, dibenamine, phentolamine) and a beta-adrenergic blocker (propranolol) decreased self-stimulation responding at 100 mug i.c.v. doses, but showed very little effect at small i.p. doses. Pretreatment with alpha- and beta-adrenergic blockers (i.c.v.) also decreased amphetamine-facilitated responding. The effects of amphetamine or cocaine (i.p.) were not significantly altered by these blockers at the doses used. The depressant effects of the alpha- and beta-adrenergic blockers on self-stimulation behavior appear to be nonspecific with respect to the type of adrenergic receptors.

Adrenergic alpha-Agonists↗