Corticotropin releasing factor (CRF) and sauvagine (SVG) when injected ICV both reduced aggressive behavior and sociability while increasing defensive behavior in isolated DBA/2 mice interacting with a group-housed intruder. SVG was more effective than CRF in producing such behavioral effects. These results add further evidence to the similarity between CRF and SVG, and are discussed in terms of the involvement of these peptides in emotional reactivity in the laboratory mouse.

Aggression↗

PubMedDate not supplied

[The maturation of the E.E.G. and sleep; genetic and environmental factors (author's transl)].

Whilst studying the post-natal maturation of reflexes, EEG activity, rhythmic activity in Slonaker's wheels and the learning of adult mice, strains showing less pronounced rhythmic activity and more immature EEG and reflexes at birth were discovered. On the other hand some strains having a shorter post-natal period manifest an early maturation of their central nervous system. The results indicate that complex interactions exist between genotype and environment when the different post-natal maturation appearances are considered and that EEG activity may be useful in assessing development.

Aging↗

PubMedDate not supplied

Cortex weight: a genetic analysis in the mouse.

Differences in forebrain weight, forebrain weight/body weight ratios, and body weight were examined for the RI strains, their progenitor strains, and reciprocal F1 hybrids. The experiment was done in two widely separated laboratories with identical procedures for feeding, watering, and removal of brain tissue. The resulting strain distribution patterns suggested the influence of two or more loci in each laboratory. However, brain weights differed in the two laboratories. Some of the strains examined exhibited increased weights for the variables under consideration, while others exhibited decreased weights or no change at all. Implications for generalizations drawn from observations obtained in any single laboratory were discussed.

Animals↗

PubMedDate not supplied

Length of social deprivation differently affects free-choice morphine consumption in C57BL/6J mice.

The effects of social deprivation on morphine consumption in C57BL/6J mice were investigated. Social or isolated animals (length of isolation: 7, 12, 17 days) were submitted to a free-choice between water and morphine hydrochloride solution (0.5 mg/ml). Isolation affects morphine consumption, with solitary housed mice drinking more morphine solution than socially housed animals. Moreover the amount of morphine intake depends on the duration of the isolation period to which mice are subjected. The importance of environmental factors on opiate consumption may be considered in terms of the possible implications of drug addiction in humans.

Analysis of Variance↗

PubMedDate not supplied

Neurochemical and behavioral responses to stress.

The relationship between the hypothalamic - pituitary - adrenocortical (HPA) and the sympathetic - adrenomedullary (SA) systems is discussed by considering their role at the central and peripheral level. HPA and SA responses are not independent of each other, which indicates a number of hormonal, monoaminergic and peptidergic reactions at the brain level. It is demonstrated that a number of interacting systems and feedback mechanisms take part in stress responses.

Adrenal Medulla↗

PubMedDate not supplied

The difference in the tail-flick but not hot-plate response latency between C57BL/6 and DBA/2J mice.

The tail-flick latency, measured using radiant heat as a noxious stimulus, was significantly shorter in C57BL/6 than in DBA/2J mice, while no significant interstrain differences were observed in the hot-plate test. The experiments in which the animals' tail was painted indicated that the difference in the tail-flick latency between strains was caused by the difference in the color of animal's coat.

Animals↗