Neonatal masculinization affects maternal behavior sensitivity in female rats

Summary The present results indicate that maternal behavior in adult neonatally androgenized female rats is significantly diminished when compared to females at oestrus and intact males. In androgenized females cannibalism was detected.Supported by Dirección de Investigación y Desarrollo S-80-26, Universidad Austral de Chile.Acknowledgment. The authors are thankful to Dr E. Rodriguez for his valuable suggestions and discussions.     

The effect of eating behavior on the circadian rhythm of plasma corticosterone in growing rats]

The circadian rhythm of plasma corticosterone was studied in growing Rats fed on an ad libitum or controlled feeding schedule (six meals per day). Circadian plasma corticosterone rhythm was conventional in ad libitum Rats. Increases of circulating hormone occurred during the last light hours and the first dark hours. Plasma corticosterone rhythm was modified by controlled feeding. Meal feeders exhibited a high value during the last light hours and a secondary hump at midnight. Feeding schedule was not the main synchronizing factor in rat circadian corticosterone rhythm.     

Suppression of pup retrieving behavior in rats following administration ofl-Δ9-Tetrahydrocannabinol

Résumé Le comportement des femelles rat rapportant ses petits au nid a été fortement influencé par le L- ⁹ A des doses de 20 mg/kg il s'est complètement arrêté.     

Circling behavior in mice and rats: possible relationship to isolation-induced aggression

The relationship between circling behavior (rotation), isolation, and aggression was investigated in normal male mice and rats. Initially the animals were tested for spontaneous nocturnal rotation, then conspecific aggression and muricidal behavior was observed for mice and rats respectively. Subsequently, animals were paired on the basis of net nocturnal rotations and either group-housed or individually housed. Four weeks later all animals were retested for the same behaviors. Spontaneous nocturnal rotation increased significantly for the isolated mice but not for the group-housed animals. Moreover, 9 of the 10 isolates became aggressive and their net rotations were significantly and positively correlated with the number of biting attacks. None of the group-housed mice became aggressive. Rats, on other hand, showed a decrease in rotation and a relationship between rotation and muricidal behavior was not evident. The possible relationship between circling behavior, aggression, and territoriality is discussed.     

Circling behavior in mice and rats: possible relationship to isolation-induced aggression

Summary The relationship between circling behavior (rotation), isolation, and aggression was investigated in normal male mice and rats. Initially the animals were tested for spontaneous nocturnal rotation, then conspecific aggression and muricidal behavior was observed for mice and rats respectively. Subsequently, animals were paired on the basis of net nocturnal rotations and either group-housed or individually housed. Four weeks later all animals were retested for the same behaviors. Spontaneous nocturnal rotation increased significantly for the isolated mice but not for the group-housed animals. Moreover, 9 of the 10 isolates became aggressive and their net rotations were significantly and positively correlated with the number of biting attacks. None of the group-housed mice became aggressive. Rats, on other hand, showed a decrease in rotation and a relationship between rotation and muricidal behavior was not evident. The possible relationship between circling behavior, aggression, and territoriality is discussed.     

Hypothalamic histamine modulates adaptive behavior of rats at high environmental temperature

Histamine content in the rat hypothalamus was lower at 4 degrees C and higher at 31 degrees C compared to that at 21 degrees C. Pretreatment with alpha-fluoromethylhistidine, a 'suicide' inhibitor of histamine decarboxylase, attenuated both the increased level of hypothalamic histamine and rat adaptive behavior at 31 degrees C. Increase of histamine content in the hypothalamus appears to be an important factor contributing to rat adaptive behavior to high environmental temperature.     

Hypothalamic histamine modulates adaptive behavior of rats at high environmental temperature

Summary Histamine content in the rat hypothalamus was lower at 4°C and higher at 31°C compared to that at 21°C. Pretreatment with -fluoromethylhistidine, a suicide inhibitor of histidine decarboxylase, attenuated both the increased level of hypothalamic histamine and rat adaptive behavior at 31°C. Increase of histamine content in the hypothalamus appears to be an important factor contributing to rat adaptive behavior to high environmental temperature.     

Operant behavior of pre and post pubertal rats irradiated with I131 in the last trimester of gestation

Résumé Les petits de rates irradiées au 14^e jour de leur gestation, avec 3000 µC/kg de¹³¹I i.p. ont montré une plus grande réduction de leur capacité à presser sur un levier lorsqu'ls l'ont appris avant la puberté. Cet effet fut d'autant plus manifeste chez les animaux qui avaient été conditionnés lentement et qui ont généralement tendance à améliorer leur performance avec l'âge.

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Supported by NIMH Grant No. NS-07889.     

Open-field behavior and acquisition of discriminative response control in Δ9-THC tolerant rats

Résumé La tolérance de l'effet du 1- ⁹-tétrahydrocannabinol ( ⁹-THC) a été examinée par une méthode nouvelle. Les résultats obtenus permettent une interprétation de tolérance pharmacologique pour ⁹-THC.

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Numbering system according to IUPAC rules. The drug was generously supplied by Dr.T. Petrzilka, University of Zürich.     

The dopamine autoreceptor agonist B-HT 920 markedly stimulates sexual behavior in male rats

Summary B-HT 920, a selective agonist at dopamine (DA) autoreceptors, strongly increased the incidence of penile erections (PE) in male rats, an effect which was dose-related and antagonized by haloperidol. B-HT 920 at 100 and 200 g/kg i.p. significantly altered the copulatory pattern of sexually active male rats, reducing the number of mounts and intromissions as well as the latency to the first ejaculation, a stimulant effect which was confirmed in sluggish males at a dose of 100 g/kg.