Short-Term Enrichment Makes Male Rats More Attractive, More Defensive and Alters Hypothalamic Neurons

Abstract

Innate behaviors are shaped by contingencies built during evolutionary history. On the other hand, environmental stimuli play a significant role in shaping behavior. In particular, a short period of environmental enrichment can enhance cognitive behavior, modify effects of stress on learned behaviors and induce brain plasticity. It is unclear if modulation by environment can extend to innate behaviors which are preserved by intense selection pressure. In the present report we investigate this issue by studying effects of relatively short (14-days) environmental enrichment on two prominent innate behaviors in rats, avoidance of predator odors and ability of males to attract mates. We show that enrichment has strong effects on both the innate behaviors: a) enriched males were more avoidant of a predator odor than non-enriched controls, and had a greater rise in corticosterone levels in response to the odor; and b) had higher testosterone levels and were more attractive to females. Additionally, we demonstrate decrease in dendritic length of neurons of ventrolateral nucleus of hypothalamus, important for reproductive mate-choice and increase in the same in dorsomedial nucleus, important for defensive behavior. Thus, behavioral and hormonal observations provide evidence that a short period of environmental manipulation can alter innate behaviors, providing a good example of gene-environment interaction.

Maternal exposure to environmental enrichment before and during gestation influences behaviour of rat offspring in a sex-specific manner

“…In our EE design, we hypothesize that 6-7 weeks of EE exposure to running wheel could have played a role in the female better cognitive performance. Our EE exposed females (future mothers) did not show modifications in anxiety-related behaviour in the EPM; literature studies show contrasting results in anxiety revealing tests (see introduction, [11][12][13][14][15][16][17]). …”

Tracing the trajectory of behavioral impairments and oxidative stress in an animal model of neonatal inflammation

“…Previously, EE has mitigated various animal models of disease and trauma (Dahlqvist et al, 2004;Spires et al, 2004;Johnson et al, 2013;Connors et al, 2014), and increased social behavior (Morley-Fletcher et al, 2003;Schneider et al, 2006) and preference directed toward animals reared in this condition (Mitra and Sapolsky, 2012). Although EE seemed to prevent further nLPS-induced reductions in social behavior, overall sociability levels were lower in EE animals than we anticipated.…”

Glucocorticoids Orchestrate Divergent Effects on Mood through Adult Neurogenesis

“…Testosterone has been reported to enhance neurogenesis (Spritzer and Galea, 2007), and levels of circulating androgens are severely reduced after chronic SD (Flugge et al, 1998), whereas EE has the opposite effect (Mitra and Sapolsky, 2012). Treatment of defeated animals with testosterone can reverse the downregulation of hippocampal 5HT1A receptors (Flugge et al, 1998).…”