Behavioral Responses Of Rats Research Articles

Chronic amphetamine alters D-2 but not D-1 agonist-induced behavioral responses in rats

In two experiments, using different drug doses and periods of drug administration, rats were given amphetamine (AMPH) either continuously (via slow-release pellets), or intermittently (via injections). In both experiments, only the rats pretreated with intermittent AMPH subsequently showed heightened responsivity to the selective D-2 dopamine agonist LY171555 but not to SKF38393 (a D-1 agonist). This altered response to LY171555 was still present 30 days after the AMPH withdrawal, implying that D-2 dopamine receptors at least partially mediate AMPH inverse tolerance effects. The behavioral response to the D-2 agonist was clearly different in animals receiving high versus low doses of AMPH, suggesting that different drug-state learning may have occurred during pretreatment. In a third experiment, in which rats were given repeated daily injections of either the D-1 or the D-2 agonist, only rats pretreated with the D-2 agonist and subsequently injected with the D-2 agonist clearly showed heightened responsivity. These data imply an important role of D-2 receptors in the AMPH inverse tolerance effect.

Effects of lateral hypothalamic lesions on food intake of rats during exposure to cold.

Lateral hypothalamic damage impaired both physiological and behavioral responses of rats during exposure to a 5 degree C environment. The brain-damaged animals usually did not conserve heat in the cold as well as control rats did, nor did they always increase their caloric intake to meet their energy needs. However, when given sucrose solution to drink instead of water, they did increase their ingestion of chow in response to cold exposure. It is likely that the elevated consumption of palatable fluid served to relieve dehydration and thereby removed its constraints on eating, thus permitting hyperphagia to occur. In contrast to these results, rats with large dopamine-depleting brain lesions, produced by intraventricular 6-hydroxydopamine treatments, always increased food intake when exposed to cold stress and demonstrated no apparent problems in peripheral vasoconstriction. Thus, it is unlikely that striatal dopamine depletions account for either the impaired feeding response or the inadequate heat conservation of rats with lateral hypothalamic lesions during cold stress.

Effect of bone marrow myelopeptide mediators on the threshold summation index and behavioral response in rats

Effect of bone marrow myelopeptide mediators on the threshold summation index and behavioral response in rats

Critical issues in assessing the behavioral effects of amphetamine

Amphetamine induces a behavioral syndrome in mammals that includes a variety of repetitive behaviors. An integral component of this syndrome in humans is the presence of a thought disturbance not unlike that manifest in idiopathic paranoid schizophrenia. The consistent pattern of behavioral changes produced by amphetamine across species, when considered in light of the psychosis it elicits in humans, has suggested to many that these drug-induced changes in animals may provide a model of the endogenous psychosis in humans. Amphetamine-induced changes in open-field behavior in the rat have been the most widely studied in attempts to formulate a model for investigating the neurobiological mechanisms underlying amphetamine psychosis and paranoid schizophrenia in humans and for testing the therapeutic efficacy of new antipsychotic drugs. The procedures used to assess the behavioral response to amphetamine, however, typically include rating scales or automated recordings that by their very nature ignore those components of the behavioral response that may be most critical for developing a viable animal model of the naturally occurring psychosis. Further, open-field behavior is often recorded during arbitrarily selected intervals without consideration for the multiphasic nature of the entire amphetamine response. We discuss how incomplete descriptive analyses of the amphetamine behavioral response in rats has led to confusion in the literature and describe behavioral research that is paradigmatic of the work we believe is most likely to eventuate in significant progress in the field.

PROCEEDINGS OF THE AUSTRALASIAN SOCIETY OF CLINICAL AND EXPERIMENTAL PHARMACOLOGISTS

PROCEEDINGS OF THE AUSTRALASIAN SOCIETY OF CLINICAL AND EXPERIMENTAL PHARMACOLOGISTS

Modulating role of lithium on dopamine turnover, prolactin release, and behavioral supersensitivity following haloperidol and reserpine.

The effects of haloperidol, reserpine, and concomitant lithium were evaluated in biochemical, endocrine, and behavioral studies in the rat. Concomitant administration of a chronic regimen of haloperidol and lithium did not prevent the development of tolerance as noted by dopamine metabolites in the striatum or olfactory tuberculum. Nor did chronic lithium alter behavioral response in rats treated with reserpine and challenged with the dopamine agonist apomorphine. Additionally, prolactin release was increased by haloperidol, but was not altered by acute or chronic lithium treatment. These findings are discussed in the light of present knowledge of pre- and postsynaptic receptor changes and the effects of lithium.

Enhanced 5-hydroxytryptamine-mediated behavioural responses in rats following repeated electroconvulsive shock: relevance to the mechanism of the antidepressive effect of electroconvulsive therapy.

Treatment of rats with one electroconvulsive shock (ECS) per day for 10 days enhanced the hyperactivity syndrome produced by administration of tranylcypromine (10 mg kg-1) and L-tryptophan (50 mg kg-1) given 24 h after the final shock. Similar enhancement was seen whether the shock was alternating sinusoidal or direct current (fractionated), whether it was given through unilaterally or bilaterally placed electrodes and whether or not a neuromuscular blocking agent (fazadinium) was used. Five shocks spread over 10 days or 8 shocks spread over 17 days were similarly effective, whilst 8 shocks in 1 day were ineffective. Therefore when ECS are given to rats in ways similar to those in which electroconvulsive therapy is given to patients with depression, enhancement of behavioural responses to increased 5-HT function is produced.

Neuronal and behavioural responses in rats during noxious stimulation of the tail.

In rats anaesthetized with urethane, extracellular unit activity has been recorded from neurones in the central nervous system during noxious stimulation of the tail. Accurately graded and sustained stimulation was achieved by immersing the whole tail in water at controlled temperatures. Neurones were found chiefly in the marginal layers of the dorsal horn near the entry of the dorsal roots supplying the tail and in the ventrobasal nucleus of the thalamus; a few neurones were also found in the somatosensory cortex. Both dorsal horn units and thalamic units showed very similar responses as the tail temperature was gradually raised. At 42°C there was an increase in firing rate which rose sharply with increasing temperatures to reach a maximum at 46°C. At higher temperatures activ­ity declined and at temperatures above 50°C was largely extinguished. The temperature-response curves were bell-shaped. The decline in activity depended on temperature and not on time: sustained firing for many minutes was seen when temperature was at or just below the peak of the bell-shaped curve. The dorsal horn and thalamic cells also responded to noxious mechanical stimulation of the tail. The receptive fields at both levels were similar, being variable in size, often bilateral and sometimes covering the whole tail. None of the central neurones showed any response to noxious stimulation other than on the tail; neither did they respond to movement of the tail nor to light mechanical stimuli applied to the tail or elsewhere. In behavioural experiments conscious rats had their tails exposed to water at various temperatures. The rats lifted their tails from the water at a threshold temperature of 43.7 ± 0.6°C, i. e. just above the threshold for the central nociceptive neurones. The findings are compatible with a specific nociceptive pathway ascending to the ventrobasal thalamus.

Further comments on deleterious behavioral and physiological effects of sound.

The use of ultrasonic sound as a means of controlling rat populations is questioned. The following points are discussed: (1) the processes of refraction and decreased audiogenic seizure susceptibility with repeated exposure to sound; (2) the genetic variability of the rat with respect to auditory behaviors; (3) the behavioral and physiological responses of organisms other than the rat; and (4) the behavioral responses of rats to ultrasonic sound at distances from the sound source. It is concluded that such a device may be effective under certain circumstances, but more data are needed with respect to the behavioral and physiological effects of ultrasonic sound before it is used for rat control.

Effects of chlorpromazine and three metabolites on behavioral responses in rats

Effects of chlorpromazine (CPZ) and three metabolites (3,7-dihydroxy-CPZ; 7,8-dihydroxy-CPZ; 7-hydroxy-CPZ) on behavioral performance of rats were tested by three methods: (a) continuous nondiscriminative lever-pressing shock-avoidance response without a warning signal; (b) discriminative pole-climbing shock avoidance and escape; (c) discriminative control of behavior by drug states. Both types of avoidance were much more impaired by CPZ than by the metabolites. The metabolite producing the most consistent impairment was 7-hydroxy-CPZ and the least consistent was 7,8-dihydroxy-CPZ. In the test for discriminative control of behavior by drug states, the 7-hydroxy-CPZ was the only metabolite which evoked the CPZ stimulus characteristics whereas the 7,8-dihydroxy-CPZ produced a generalized depressant effect.

Mouse killing or carrying by male and female Long-Evans hooded rats

The behavioral responses of rats toward mice were studied. A portion of the rats killed the mice, as found in previous studies. Another group of rats exhibited a different, previously unstudied response of mouse carrying (without the kill). A behavioral study of the stability of mouse killing or carrying was carried out. The behaviors were found to be stable over two trials in 1 day and over 5 consecutive days of testing. The possible behavioral significance of the carrying response was also discussed.

Behavioural Responses of Rats to early Overnutrition

The consequence of early overnutrition on later behaviour of rats was tested during the first year of life under conditions of different complexity. The behaviour patterns of overfed rats were compared with those of animals, kept under common nutritional conditions and of rats undernourished prior to weaning. It was demonstrated, that early overnutrition is not beneficial for later exploratory behaviour, learning ability, and the resistance to the pharmacological or nutritional stress. The trend of the observed behavioural responses was identical both in the over- and undernourished rats, differences appeared to be quantitative rather than qualitative.

Behavioural Response of Rats During Inhalation of Trichloroethylcnc and Carbon Disulphide Vapours

Behavioural Response of Rats During Inhalation of Trichloroethylcnc and Carbon Disulphide Vapours