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At least 1,603 records · Page 89Linked to original sources
PubMed1975

Primate drinking system as defined by electrical stimulation of the brain (ESB).

Four rhesus monkeys were examined by ESB for drinking sites in structures that had been previously demonstrated to support drinking behavior. Three yielded a significantly greater proportion of drinking sites than expected from the earlier study, and one yielded significantly less. As the exploration proceeded, the proportion of sites yielding drinking greatly increased in the drinkers and decreased in the nondrinker, and the ratio of stimulus-bound to nonstimulus-bound drinking sites increased in the drinkers but decreased in the nondrinker. Orienting responses decreased in both drinker and nondrinker as exploration proceeded. Two sites that had reliably supported drinking in the restraint chair failed to do so when telestimulated in a free environment, but instead yielded turning, walking, and climbing behavior. The results suggest that ESB-elicited drinking is determined by stimulation of several overlapping neural systems. These probably include ascending dopaminergic and cholinergic systems which are relatively thirst specific, and a nonspecific, cholinergic component of the reticular activating system which triggers the animal to execute a prepotent response which is specific to a given animal with a given history of stimulation under particular enviromental constraints. The learning of stimulus bound drinking is proposed to have its neural locus within the system which mediates the prepotent response, rather than in a thirst system or general activation system.

Animals↗
PubMed1989

Scopolamine impairs response-to-change based on distal cues in the rat.

The effect of a scopolamine injection (1 mg/kg, IP) on response-to-change behavior was investigated in two experiments. After exploration of a T-maze with one arm black and the other white (Trial 1), rats were tested with both arms either black or white (Trial 2). Experiment 1 revealed that the opportunity to make body turns into the arms did not help scopolamine-injected rats to locate the changed arm after visual exploration of the arms during Trial 1. Saline-injected animals chose the changed arm. In Experiment 2, rats were allowed to move freely into the arms during Trial 1. During Trial 2, they were tested either from the same start as that used during Trial 1 or from a different start 180 degrees from the original start. While scopolamine-injected animals reacted appropriately to the change when tested from the same start, they were impaired when tested from the opposite start. In both conditions, saline-injected animals chose the changed arm. These results, together with others, support the notion that the cholinergic system plays a crucial role in the processing of distal information.

Animals↗
PubMed1990

The rat's right-left preference during free exploration of a multiple Y-maze.

The right-left preference of Wistar, Sprague-Dawley, and Long Evans rats of both sexes was investigated in a multiple Y-maze in which the animals had to perform three consecutive right-left choices in order to go from the common starting point to one of the eight goal arms. The rats were free to explore the maze without being subjected to punishments or rewards. Care was taken to minimize inhibitory influences on exploration (low illumination, no handling to return the rats to home cage). The statistical analysis of the total right-left choices performed by the rats showed that three groups (Wistar females, Sprague-Dawley females, and Long Evans males) exhibited a preference for the right. This preference was not related either to sex or strain, but was possibly a species characteristic.

Animals↗
PubMed1991

Effects of early postnatal gonadal steroids on extinction of a continuously food-rewarded running response.

In the present work the existence of sex differences (Experiment 1) on the acquisition and extinction of a continuously reinforced response in a short and narrow runway (100 x 9 x 10 cm) were investigated. In addition to the investigation of the basic sex differences in Experiment 1, the effect of postpuberal gonadectomy of male and female rats and the role of the early postnatal gonadal steroids on these situations were also examined in Experiments 2 and 3, respectively. In all experiments, no sex differences were found in acquisition. However, males extinguished faster than female rats. Gonadectomy of both sexes in adulthood, although it increases their latencies in acquisition, did not affect the differences between sexes during extinction. In contrast, in Experiment 3 female androgenization and male orchidectomy on day one after birth reversed the direction of sex differences found between control rats in the extinction period. Our findings suggests that the observed sex differences in extinction may be due to an underlying sexual dimorphism in the response inhibition process.

Androgens↗
PubMed1993

Scopolamine affects response-to-change test involving 20-min retention interval after locomotor exploration in rats.

The tendency to select the T-maze arm that has been changed in brightness between two successive trials (response-to-change) was investigated. Our previous findings indicated that scopolamine injections (1.0 mg/kg) impaired responding to change of brightness in a choice trial (trial II) following a 1-min retention interval, when in the first acquisition trial rats could only inspect the white-black T-maze arms through transparent partitions (the passive test). The drug was ineffective when rats were allowed locomotor exploration of the maze (the active test). The aim of the present experiment was to investigate the effect of the same dose of scopolamine on the active test involving a longer 20-min retention interval between the acquisition trial and the choice trial. The effect of cue salience also was examined by using grey-black arms. Rats injected with scopolamine (Scopo) 20 min before the acquisition trial performed in the white-black maze on the chance level, whereas saline-injected rats (Sal) showed significant preference for the changed arm. Decreasing the cue salience impaired response-to-change in Sal rats (50% of changed arm choices) but had no further effect on performance of Scopo rats, presumably because of a floor effect. The postacquisition injection had a somewhat stronger effect than the injections preceding acquisition, which most probably reflects the state dependency phenomenon. The deficient performance due to scopolamine treatment that appeared in the present study at a longer retention interval could be interpreted in terms of increased forgetting.

Animals↗
PubMed1982

Sex-dependent biological changes following prenatal nicotine exposure in the rat.

Nicotine was administered to adult female rats in drinking water starting 6 weeks before mating and continuing throughout pregnancy. The litters were cross-fostered to control dams at birth. Prenatal nicotine treatment reduced both the number of male rats born and the male birth weight. Female offspring were not significantly affected. Rearing activity was reduced in male but not female offspring either when tested over a 24 hour period in a home cage environment or during a 10 minute exposure in an open field. Horizontal locomotor activity was reduced only during the first 5 minutes in the open field and again the effect was found only in the males. Baseline plasma corticosterone levels were reduced in both male and female offspring but there was no effect on stress-elevated corticosterone levels.

Animals↗
PubMed1984

Systematic comparison of apomorphine-induced behavioral changes in two mouse strains with inherited differences in brain dopamine receptors.

Dosage and time dependencies of apomorphine-induced changes in stereotyped behaviors (climbing, gnawing and sniffing), locomotor activity and rearing activity were compared in young adult male mice of two inbred strains, DBA/2 and C57BL/6. These two strains are known to differ in their genetically specified brain dopamine receptor number. Apomorphine administered intraperitoneally at dosages of 0.5-20 mg/kg failed to induced stereotyped climbing in DBA/2 at any of the doses tested but markedly increased climbing in C57BL/6 at higher dosages. Apomorphine-induced stereotyped gnawing occurred in both strains at higher dosages although the latency was shorter and maximal effect greater in C57BL/6. Stereotyped sniffing was induced in both strains to a comparable degree at doses greater than or equal to 2.0 mg/kg, and the duration of this stereotypy was indistinguishable between strains. Locomotor activity was inhibited maximally in DBA/2 at an apomorphine dosage of 2 mg/kg and was inhibited to a greater extent than was C57BL/6. Rearing was inhibited in both strains by doses of apomorphine greater than or equal to 0.5 mg/kg; however the duration of the effect was considerably greater in DBA/2 than in C57BL/6. These data suggest that genetically determined differences in central dopamine receptors may have profound and selective effects on behaviors mediated by dopamine pathways; that complex behavioral patterns, e.g., apomorphine-induced stereotypy, may be dissected in to individual components by identifying neuropharmaco genetic differences between strains; that marked strain-specific, inherited differences in dopamine agonist-induced behavioral changes do occur among inbred, non-mutant mouse strains and that their occurrence in other mammalian species including man should be considered.

Animals↗
PubMed1986

Microinjections of methyl-beta-carboline-3-carboxylate into the dorsal raphe nucleus: behavioural consequences.

Very small quantities (0.01-10 ng) of the inverse benzodiazepine receptor agonist, methyl-beta-carboline-3-carboxylate (beta-CCM) microinjected into the dorsal raphe nucleus (DRN) of the rat selectively reduced social interaction, an effect consistent with an increase in anxiety. Similarly, intraperitoneally injected beta-CCM, within a limited dose range, reduced social interaction without affecting locomotor activity. The benzodiazepine receptor antagonist, RO15-1788 (1 ng) microinjected into the DRN, reversed the suppression of social interaction induced by either intra-raphe or intraperitoneal beta-CCM. Histological examination of the beta-CCM microinjection sites showed that locations within the DRN were almost invariably associated with decreases in social interaction; microinjections failing to decrease social interaction were located primarily outside the DRN. We conclude that the DRN has a major role in expressing the anxiogenic effect of beta-CCM and it may therefore be an important area in the neuronal system controlling anxiety.

Animals↗