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Biomedical subjects

S N Pradhan

Publications and source records attributed to S N Pradhan.

At least 19 recordsLinked to original sources
PubMed1992

Glycaemic index of conventional carbohydrate meals.

The glycaemic index (GI) and the triacylglycerol response were measured in thirty non-insulin-dependent diabetes mellitus patients given 50 g portions of five different conventional Indian meals containing semolina (Triticum aestivum) cooked by two different methods, or combinations of semolina and pulse (black gram dhal (Phaseolus mungo), green gram dhal (Phaseolus aureus) or Bengal gram dhal (Cicer arietum)). There were no significant differences among meals in mean GI except for meals based on roasted semolina or semolina-black gram dhal. Compared with the blood glucose response for a 50 g glucose load, only meals based on steam-cooked semolina and semolina-Bengal gram dhal elicited a significantly lower response at 1 h postprandially, and only meals based on semolina-black gram dhal at 2 h postprandially. No significant differences were found among the meals in the triacylglycerol-response.

Blood Glucose↗
PubMed1991

Behavioral effects of ethanol inhalation in rats.

Behavioral effects of ethanol inhalation were studied on two fixed-ratio (FR) liquid-reinforced schedules and a continuous reinforcement (CRF) schedule intracranial self-stimulation (SS) in rats using the inhalational behavioral chamber designed in our laboratory. In the FR-24 schedule ethanol caused a decrease of reinforcement rate at 161 ppm and higher concentrations. In the FR-50 schedule decreases of the rate were observed at 102 ppm and 203 ppm. In the SS behavior ethanol produced a decrease in the rate of reinforcement at 603 ppm and higher concentrations. In rats of this schedule, blood ethanol concentrations were measured to be 393 micrograms/ml and 545 micrograms/ml after exposure to 600 ppm and 1200 ppm of ethanol respectively. Acute tolerance to ethanol was observed in these experiments, particularly in the FR-24 schedule. Thus ethanol inhalation could produce adequate blood concentrations so as to produce behavioral effects.

Administration, Inhalation↗
PubMed1991

Effects of ethanol inhalation on EEG in rats.

Effects of ethanol on duration of stages of sleep-wake cycle and EEG power spectra were measured during a 2-h exposure in a dynamic inhalational chamber in rats. Rats were exposed to one of four graded concentrations (approx. 100, 400, 800 and 1600 ppm) of ethanol on different days. Ethanol was found to increase the duration of waking (W) with a decrease in duration of rapid eye movement (REM) sleep at 100 and 400 ppm. No effect was observed at 800 and 1600 ppm on the stages of sleep-wake cycle or at 100-1600 ppm on EEG power spectra from the somatosensory or visual cortices. Results indicate that ethanol administered by inhalation could produce arousal action at low doses, but did not have any effect on EEG power spectrum at the concentrations used.

Administration, Inhalation↗
PubMed1979

Interactions between motor activity and sterotypy in cocaine-treated rats.

Effect of a single administration of a dose (5, 10, or 15 mg/kg, i.p.) of cocaine hydrochloride on spontaneous motor activity (SMA) and stereotypy (ST), and interactions between these behaviors were investigated in rats. SMA showed peak increases within 10 min and at 120 min after cocaine injection. Drug-induced stereotypy was maximal during the interval between these two peaks in SMA. Several neurotransmitters may be involved in the interactions between SMA and ST.

Animals↗
PubMed1979

Actions and interactions of cocaine on self-stimulation behavior in rats.

The effect of cocaine, over a dose range of 2--60 mg/kg, i.p., on self-stimulation (SS) behavior was studied in rats with electrodes either in the posterior hypothalamus (PH, monoaminergic) or the area ventralis tegmentum (A10, dopaminergic). The drug increased SS behavior with peak effects at 30 mg/kg in PH rats and 20 mg/kg in A10 rats. Azaperone (an alpha-adrenergic blocker) and haloperidol (an antidopaminergic neuroleptic) given at doses that did not affect baseline SS responses reduced cocaine-induced enhancement of SS in both PH and A10 rats, showing the involvement of both noradrenergic and dopaminergic mechanisms in SS behavior. A scopolamine dose that itself facilitated SS responding enhanced the effect of cocaine on this behavior, thus suggesting an additional involvement of cholinergic mechanisms in cocaine effect.

Animals↗
PubMed1979

Electrophysiological correlates of the behavioral effects of tubocurarine in conscious cats.

The effects of tubocurarine on behavior, electrical activity, and auditory evoked potentials were studied in restrained conscious cats. Tubocurarine hydrochloride (doses of 0.05--1 micrograms intraventricularly) produced various central stimulatory effects characterized by EEG desynchronization, decrease in both low (7--9 Hz) and high (10--14 Hz) alpha waves, and decrease in the amplitude and area of the surface positive (P1) wave of auditory evoked potentials. Concomitant with the alterations in brain electrical activity tubocurarine hydrochloride produced generalized behavioral arousal phenomena and the cats became restless and exhibited miaowing and increased movement of the head and ears. Almost all parameters except behavior showed a distinct dose-response relationship. A correlation between the behavioral effects and the EEG analog was thus demonstrated.

Alpha Rhythm↗
PubMed1979

Actions and interactions of amphetamine on self-stimulation in rats.

The dose-response relationship for d-amphetamine (0.125-2 mg/kg, IP) and its l-isomer (0.125-3 mg/kg, IP) was studied in self-stimulation behavior of rats each with an electrode at posterior hypothalamus (PH, mainly monoaminergic) or area ventralis tegmentum (A10, dopaminergic). The drug effects increased with the dose reaching a peak (at 0.5 mg/kg with d-amphetamine and at 1.0 mg/kg with 1-amphetamine) and then decreased. The d-isomer was approximately twice as potent as the l-isomer in enhancing intracranial self-stimulation (ICSS) rate with electrodes at either site. Azaperone (mainly an alpha-adrenergic blocker) and haloperidol (an antidopaminergic neuroleptic) used in small doses (0.05 and 0.008 mg/kg respectively) which did not affect the baseline responding, blocked amphetamine-induced enhancement of ICSS in both groups of rats. Thus, amphetamine-induced facilitation of ICSS at both PH and A10 areas and its blockade by an alpha-adrenergic blocker as well as an antidopaminergic neuroleptic show the involvement of both noradrenergic and dopaminergic mechanisms in self-stimulation behavior.

Amphetamine↗
PubMed1979

Modification of behavioral and neurochemical effects of cocaine by haloperidol.

Cocaine (20 mg/kg, i.p.) stimulated spontaneous motor activity (SMA) and induced stereotypy (ST) in rats. Haloperidol at 0.015 mg/kg, i.p. dose reduced or blocked cocaine-induced ST, but did not affect, drug-induced hyperactivity. At 0.03 mg/kg, i.p. dose of haloperidol, both behavioral effects were blocked. Cocaine decreased the norepinephrine (NE) and serotonin (5-HT) contents of diencephalon-midbrain (DM) and pons-medulla (PM) and increased dopamine (DA) contents in the DM and caudate nucleus (CN) at 20 min after its administration. Haloperidol (0.03 or 0.015 mg/kg) at 30 min postdrug produced opposite effects on the levels of NE, DA and 5-HT in the respective brain areas compared to cocaine. Given in combination, haloperidol reversed the effects of cocaine on the levels of NE, DA and 5-HT. Thus the cocaine-induced behavioral changes and their modification by haloperidol can be correlated to the neurochemical changes produced by these drugs alone or their combination.

Animals↗
PubMed1979

Inhibition of behavioral effects of cocaine by actinomycin D in rats.

Interactions of actinomycin D (AD, 25 micrograms--50 micrograms/kg intraperitoneally, i.p., or 1 microgram intracerebroventricularly, i.c.v.) with repeated cocaine administration (15 mg/kg i.p. twice daily at 8-hr intervals) were investigated on the spontaneous motor activity (SMA) and stereotypy (ST) in rats. Following repeated injections of cocaine in combination with saline (i.p. or i.c.v.), both SMA and ST were gradually increased to their peaks on day 9, then decreased up to the day 19 and thereafter maintained at higher than normal levels. Given along with cocaine or saline, AD (i.p. or i.c.v.) caused gradual and significant decreases of SMA and ST. On stopping AD (i.p. on day 5 and i.c.v. on day 9) injection, both SMA and ST increased again. After stopping its i.c.v. injection both behaviors were increased to their peaks on day 10, then gradually decreased to and maintained at slightly higher than normal levels on day 18 onwards. The possible mechanisms of actions of AD as an inhibitor of cocaine-induced behavioral effects have been discussed.

Animals↗
PubMed1978

Carcinogenicity of some folk medicinal herbs in rats.

Twelve medicinal herbs were bioassayed to correlate a high incidence of esophageal carcinoma in natives of different places with their habitual consumption of these products. Outbred NIH Black rats were given 72 weekly sc injections of the total aqueous extracts of the plant materials. The tanninrich plant extracts from Areca catechu and Rhus copallina produced local tumors in 100 and 33%, respectively, of the experimental animals. Other materials included Diospyros virginiana and extracts from plants not rich in tannins. Diospyros and extracts of Sassafras albidum and Chenopodium ambrosiodes were tumorigenic in over 50% of the treated animals.

Animals↗