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Biomedical subjects

H Lal

Publications and source records attributed to H Lal.

At least 199 records · Page 11Linked to original sources
PubMed1976

Secondary reinforcement property of a stimulus paired with morphine administration in the rat.

Rats learned to run to the correct arm of a Y-maze. Correct responses were reinforced with morphine injection paired with a conditional tone stimulus. After the maze response was well established, extinction trials were run. During extinction half of the animals received neither morphine nor tone as a consequence of a correct response, while the other half received the tone but no morphine. Rats receiving the tone during extinction required significantly more trials to reach the extinction criteria than rats not receiving tone presentations. Extinction with the tone also facilitated relearning of the maze response. The results support the view that morphone is a potent reinforcer, and that stimuli paired with morphine administration acquire the properties of a secondary reinforcer.

Acoustic Stimulation↗
PubMed1976

Blockade of apomorphine-induced aggression by morphine or neuroleptics: differential alteration by antimuscarinics and naloxone.

Both morphine and the neuroleptics, haloperidol and oxyperomide, dose-dependently reduce the aggression in rats produced by 20 mg/kg of apomorphine, a dopamine receptor stimulant. The narcotics antagonist, naloxone, prevents this effect of morphine but not the effect of neuroleptics. Dexetimide, a centrally acting antimuscarnic drug, antagonizes the reduction in aggression produced by the neuroleptics, but does not affect morphine's action. The cholinergic agonist, pilocarpine, enhances this action of oxyperomide. These results suggest that a cholinergic component contributes to the anti-agression action of neuroleptics and demonstrates a difference in the mechanism of action between neuroleptics and morphine.

Aggression↗
PubMed1976

Effects of 1,1,1-trichloroethane administered by different routes and in different solvents on barbiturate hypnosis and metabolism in mice.

A 24-hr inhalation of 1,1,1-tricholoroethane (methylchloroform), 3,000 ppm, reduced pentobarbital hypnosis and increased hexobarbitaloxidation by the 9,000 x g liver supernatant fraction in male mice. On the other hand, an ip injection of methylchloroform, l ml/kg, increased the duration of pentobarbital hypnosis and reduced hexobarbital metabolism by the liver microsomal enzymes. The potentioating effect of methylchloroform on pentobarbital hypnosis as diminished when it was diluted with olive oil, but was markedly enhanced when diluted with dimethysusoxide (DMSO) before injection. Three local applications of methylchloroform )1:1 dilution with DMSO) had an effect similar to that of inhalation on pentobarbital hypnosis.

Administration, Topical↗
PubMed1975

Paradoxical absence of aggression during naloxone-precipitated morphine withdrawal.

Aggression, which is normally seen during withdrawal from narcotics, could not be produced in morphine-dependent rats by the administration of naloxone at doses which causes other signs of withdrawal. Apomorphine injected instead of naloxone was capable of producing aggression, without other withdrawal signs. Naturally occurring aggression (72-hr withdrawal) was enhanced by apomorphine and unaffected by naloxone.

Aggression↗
PubMed1975

Differential antagonism by the antichlolinergic dexetimide of inhibitory effects of haloperidol and fentanyl on brain self-stimulation.

Haloperidol (0.08 mg/kg) or fentanyl (0.16 mg/kg) injected subcutaneously suppressed bar-pressing for brain-stimulation in rats, implanted with electrodes in the lateral hypothalamic area of the medial forebrain bundle. Increasing doses: 0.04, 0.16, 0.63 and 2.50 mg/kg of the central anticholinergic dexetimide gradually antagonized the haloperidol effects. The highest dose of dexetimide did not reduce the fentanyl-induced inhibition. The results, together with a literature survey on the anticholinergic effects on neuroleptic-induced catalepsy and inhibition of avoidance behavior, are related to biochemical findings and clinical effects.

Animals↗
PubMed1975

Effect of loperamide, haloperidol and methadone in rats trained to discriminate morphine from saline.

In an operant procedure of lever pressing at FR10 schedule of food reinforcement, rats were trained to respond differentially in order to discriminate the effects of morphine (10 mg/kg) injections from those of saline injection. These rats learned to press a lever on one side after morphine injection and a lever on the opposite side after saline injection. In subsequent testing, these rats reliably emitted responses on the morphine lever after 10 or 20 mg/kg of morphine IP, 50 mg/kg of morphine given orally or 2 mg/kg methadone. Two mg/kg of morphine (or 10 or 20 mg/kg given orall) was recognized as saline. In contrast, after either loperamide (an antidiarrheal drug) given in doses up to 10 mg/kg or haloperidol (a neuroleptic) given in doses up to 0.32 mg/kg, all responses were made on the saline lever. Higher doses suppressed responding. Since neither the antidiarrheal activity nor the neuroleptic activity was sufficient to provide the discriminable cue associated with morphine, it is suggested that specific central effects produced only by narcotic analgesics are the basis for these morphine cues.

Animals↗