Behavior In Male Wistar Rats Research Articles

Environmental lighting and muricidal behaviour in the male Wistar rat

Effects of different conditions of environmental lighting on the appearance of the muricidal behaviour in male Wistar rats have been studied. The animals were kept under different conditions of environmental lighting: 1) natural day light alternated with the dark of the night; 2) sodium, continuous light emitted by a sodium steam lamp; 3) neon, continuous light emitted by fluorescent neon tubes. The continuous sodium steam light increased the percentage of animals becoming muricide when compared to animals bred in a natural environment with a normal succession of day-night lighting. On the contrary, this percentage decreased if the rats of the same group are exposed to continuous light emitted by fluorescent neon tubes. As the exposure of rats to an environment under continuous light causes a reduction of the cerebral content of serotonin, the muricidal behaviour provoked in naturally non-muricide rats by this type of lighting could be related to this depletion.

Lesions of the SDN-POA inhibit sexual behavior of male wistar rats

Discrete bilateral lesions in the SDN-POA of sexually naive adult male rats were found to decrease the number of animals ejaculating and/or to increase latencies to the first mount, intromission and ejaculation. The deleterious effects of the lesions disappeared after 4 tests for sexual behavior but were reinstated when the males were tested under suboptimal conditions i.e., when they were tested with a marginally receptive female or when they had only limited access to the stimulus female. It was subsequently shown that males with a bilaterally lesioned SDN-POA still showed an increase in plasma testosterone, LH and prolactin levels in response to sexual stimulation. Effects of the lesions on scent marking were not found. Together with previous data indicating that SDN-POA-lesions disrupt masculine sexual behavior in females, these data are taken as evidence that the SDN-POA plays a role in the regulation of masculine sexual behavior. The data further suggest that previously reported negative results of SDN-POA-lesions on masculine sexual behavior in male rats might be attributed to the use of sexually experienced instead of sexually inexperienced animals.

Effects of detention and illumination on rats' exploratory behavior in a two-box apparatus

The effects of detention and lighting intensity on the exploratory behavior of male Wistar rats have been investigated by means of several types of two-box apparatus. Experiments consisted of six consecutive daily trials. Step-through latency values were taken up to 180 sec. Even a very short detention (10 sec) within the starting box exerted a powerful inhibitory influence on the exploratory behavior of the subjects. Uniformly well-lighted surroundings (both boxes) exerted an equally powerful inhibitory influence on the same behavior. This inhibition was only slightly decreased by the availability of visual cues. Only in the apparatus in which at least one box was dark was the exploratory behavior well maintained. Both detention and bright lighting inhibited selectively the exploratory, locomotor behavior of these animals and did not inhibit other motor activities. In fact, groomings and attempts (abortive passages from one box into the other) were repeatedly performed during the increased step-through latency. These activities are discussed as indicators of a conflict between drives.

Effects of light intensity on passive avoidance behavior of male and female wistar rats

Groups of intact male and female Wistar rats were exposed to a standard passive avoidance procedure. The intensity of the light bulb illuminating the platform during adaptation, pre- and post-shock trials was manipulated (5, 25 or 75 W). Entrance latencies during pre-shock trials were longer for males than for females. They decreased for both males and females as light intensity was increased. Entrance latencies increased over trials for males but not for females. On the post-shock trial, more females than males reentered the compartment in which they previously had been shocked, with shorter entrance latencies. Thus, although light intensity functionally affected the behavior of males and females on pre-shock trials, it did not influence the behavioral differences usually observed on the post-shock trial. These data are interpreted as further evidence for the notion that the behavior of male Wistar rats in standard passive avoidance procedures is a function of non-specific effects of shock presentation per se. It is suggested that research aimed at understanding basic (neuronal) differences between males and females is necessary to be able to specify the nature of the variables responsible for the observation of behavioral differences between males and females in this and other experimental paradigms.

Effects of scopolamine on radial maze performance in rats

The behaviour of male Wistar rats given repeated daily injections of scopolamine (0.5 mg/kg) over a 14 day acquisition period was compared with that of controls treated with isotonic saline on an 8-arm radial maze. Following this were 2 test days when the group learning the task under scopolamine received saline and vice-versa. Scopolamine significantly impaired acquisition of the radial maze task, but animals rapidly improved when tested without scopolamine. Animals trained on the task without scopolamine were significantly impaired when treated with it. Those animals using non-spatial strategies were relatively resistant to the effects of scopolamine. The results are discussed in terms of the similarity of effect of hippocampal lesions and anticholinergic drug treatment, and in relation to recent theories concerning the role of the hippocampus in spatial memory.

Effects of lesions of the midbrain raphe nuclei on avoidance learning in rats

The present study evaluated the effects of electrolytic lesions of midbrain raphe nuclei (the nucleus raphe dorsalis and nucleus raphe medianus) on one-way and two-way avoidance behavior in male Wistar rats. Serotonin depleting lesions enhanced acquisition of avoidance and increased general activity of animals. These lesions also improved the performance during retention testing in rats that had learned two-way avoidance.

Effects of two special diets on the body weight of rats

The authors studied the effects of 2 special diets on the weight behaviour of male Wistar rats (aged 4--5 weeks) from Schönerlinde near Berlin up to the age of 35 weeks. The weight behaviour of rats fed a standard diet (commercially available pellets) lies between those of the experimental rats and near that of the rats on low-fat (3%) diet. The one special diet that contains 3% of fat is low-fat (8.4% of the gross energy of the feed) and high-protein (69.3% of the gross energy); the other diet that contains 50% of fat is high-fat (76% of the gross energy). The two diets (containing 331 and 612 kcal/100 g, respectively) are not isocaloric but the animals on the low-fat diet ate twice as much as the animals on the high-fat diet. The rats on the high-protein low-fat diet were prone to copious sweating. It was generally noticed that the animals on the high-fat diet became to a greater extent hypokinetic with increasing age. The weight difference between the two dietary groups increased with increasing age, reaching its maximum value (77%) at the age of 24 weeks and then decreasing to 60% (at the age of 35 weeks). Up to the age of 12 weeks, the rats are in the more "dynamic" phase of weight increase; and from the 16th week, in the more "static" phase of weight increase.

The effects of psychotropic drugs on exploratory and stereotyped behaviour of rats studied on a hole-board

Exploratory and stereotyped behaviour of Male Wistar rats was studied on a hole-board. The two forms of behaviour were differentiated according to the pattern of hole-dipping activity. Increasing doses of dl-amphetamine stimulated both forms of behaviour with stereotyped behaviour becoming predominant particularly at the higher dose levels. At the highest dose of amphetamine used (16 mg/kg) a gradual transition from exploratory to stereotyped behaviour was observed with time. As the drug wore off this transition was reversed. Haloperitol at a dosage of 0.1 and 0.05 mg/kg blocked the response to a high dose of amphetamine whereas a lower dose (0.02 mg/kg) blocked the stereotyped response to amphetamine while some exploratory behaviour still took place. Apomorphine inhibited hole-dipping but at lower doses another form of exploratory behaviour was induced, this behaviour becoming stereotyped as the dose was increased. It is concluded that there is a close relationship between exploratory and stereotyped behaviours. Monoamine systems appear to play a significant role in the regulation of both forms of behaviour.

L‐DOPA effects on sexual behaviour: An experimental Study

Abstract Following the observation by Benkert (1972), that L‐DOPA influences the sexual behaviour of rats, we studied the L‐DOPA (5.6 mg/kg), I.P. induced sexual behaviour in male Wistar rats (average weight of 350 g), in relation to side‐effects on blood hormone levels and via indirect side‐effects of the sexual partner. A percentage of time spent in sexual behaviour was achieved by counting the number of sexual responses over a post injection hour. A camera set to record 15 slides per minute was placed in the animal behaviour room and thereby eliminated the necessity of distracting human observers. This film record also allowed a more slow and careful analysis by several different researchers at their own time convenience. A record of individual animal behaviour changes with time was also possible. L‐DOPA brought about no definite change in amount of time spent in overall sexual activity, though it may have been responsible for an increase in the amount of time spent in mounting.

Modification of the isolation-induced abnormal behavior in male wistar rats by destructive manipulation of the central monoaminergic systems

Isolated male Wistar rats exhibited muricide, friendly or indifferent behavior when exposed to mice. Rats from each category were treated with α-methyl-p-tyrosine, 6-hydroxydopamine and electrolytic lesion of the midbrain-raphe nucleus and reexposed to mice at regular intervals. Aggregated control rats were treated similarly. All three treatments rendered the indifferent rats more reactive and aggressive after 6-hydroxydopamine and midbrain-raphe lesion. The friendly rats became less reactive post-treatment, then recovered, but never exhibited aggression. The muricide rats were virtually unaffected by any treatment. A third of the aggregated control rats showed aggressive and muricide behavior both after 6-hydroxydopamine and midbrain raphe lesions.