Genetic and environmental influences on behavioral and neurochemical aspects of emotionality in rats

Abstract

Three pairings of rats (two derived from divergent, selective breeding and one from divergent environmental conditions) were compared with regard to behavioral and hormonal parameters. Striking differences were observed: results obtained in our own laboratory as well as those found in a review of the literature pointed to higher emotionality (e.g., increased defecation and corticosterone secretion, etc.) in Roman low-avoidance, Wistar-Kyoto and group-housed rats, as compared to their respective counterparts, Roman high-avoidance, spontaneously hypertensive, and individually housed Wistar rats. Concomitant receptor binding studies reviewed here (3H-diazepam- and 3H-imipramine-binding sites) have revealed, however, less consistent intrapair differences.

Behavioral, Physiological, and Neuroendocrine Stress Responses and Differential Sensitivity to Diazepam in Two Wistar Rat Lines Selectively Bred for High- and Low-Anxiety–Related Behavior

“…Following exposure to a more severe stressor (forced swimming), the difference in ACTH and corticosterone increase was less evident than after plusmaze testing (Table 1), again suggesting a "ceiling effect" and consistent with differential HPA reactivity to mild (novel environment), but not to more severe (immobilization, footshock) stressors in the Roman rats (Gentsch et al 1988;Walker et al 1989).…”

“…As far as the results obtained so far indicate, our lines fit well into the general picture that emerges from the literature on selective breeding projects. It seems that such selection has mostly resulted in common characteristics that differentiate the lines/strains in emotionality or emotional reactivity and general coping style, with high levels in the former associated with rather passive strategies in the latter (Bohus et al 1987;Brush 1991;Castanon and Mormède 1994;Cools et al 1993;Gentsch et al 1988;Steimer et al 1997;Walker et al 1992). The endocrine data, on the other hand, are sometimes contradictory (Abel 1991;Brush 1991;Courvoisier et al 1996), indicating that the activity of the HPA system is not necessarily tightly linked to the type of behavioral reactivity in stressful situations.…”

“…19 , NO . 5 sponses to environmental challenges have emerged (Brush 1991;Castanon and Mormède 1994;Cools et al 1993;Gentsch et al 1988;Walker et al 1992). Recently, we reported the establishment of two Wistar rat lines selectively bred for differing behavioral performances in the elevated plus-maze test, now termed high-anxiety-related behavior (HAB) and low-anxiety-related behavior (LAB) lines, respectively ).…”

“…A correlation between the type of behavioral stress response; namely, an active coping strategy (often associated with low emotionality) or a passive coping strategy (coupled with high emotionality), and the degree of neuroendocrine reactivity has been demonstrated in many studies (Bohus et al 1987;Castanon and Mormède 1994;Cools et al 1993;Gentsch et al 1988;Walker et al 1992). Tests of neuroendocrine reactivity have focused predominantly on the hypothalamopituitary-adrenocortical (HPA) axis, the activity of which not only reflects the stress response of the organism, but may also be dysregulated in, for example, socially stressed (subordinate) rats (Blanchard et al 1995;Mormède et al 1990) and patients suffering from depression and anxiety disorders (Holsboer et al 1987;Tyrer 1992).…”

Neuroendocrine and Behavioral Effects of Repetitive Transcranial Magnetic Stimulation in a Psychopathological Animal Model Are Suggestive of Antidepressant-like Effects

“…Moreover, animals genetically predisposed to certain behavioral strategies offer a unique opportunity to test therapeutic agents that are a potential treatment for abnormal behaviors, e.g., in human psychiatric disorders (Gentsch et al 1988). Thus, studies on aberrant patterns in these selected laboratory animals may contribute to a better understanding of human psychopathology states.…”