Restraint-stress-induced changes in exploratory behavior appear to be mediated by norepinephrine-stimulated release of CRF

Exposure to intense noise can trigger a cascade of neuroendocrine events reminiscent of a stress response, including activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Using male Fischer and Lewis rats, which exhibit differences in their corticosterone response to stressors, this investigation assessed effects of acute noise exposure on neurochemical and neuroendocrine responses. In response to the noise exposure, Fischer rats displayed greater plasma adrenocorticotropin-releasing hormone (ACTH) and corticosterone responses than their Lewis counterparts. However, both strains responded with similar increases of plasma prolactin, suggesting that strain differences in the HPA response were not likely because of differences in noise perception. Post-mortem analyses revealed that noise exposure induced strain-dependent variations of corticotropin-releasing hormone (CRH) across several brain regions. These effects were evident irrespective of whether the rats were noise exposed in a familiar (home cage) or unfamiliar environment. In vivo, dynamic assessment of immunoreactive (ir)-CRH at the pituitary gland revealed that noise exposure elicited an immediate rise in ir-CRH among Fischer rats, relative to the delayed response in Lewis rats. Similarly, the rise in local interstitial corticosterone was more rapid and pronounced in Fischer rats. In contrast to these differences, ir-CRH released at the central nucleus of the amygdala (CeA) was gradual and protracted following noise exposure in both strains. Behaviorally, the Fischer rats displayed an active stress response, whereas the Lewis strain adopted freezing as a defensive style. The role of CRH in the genesis of the overall straindependent response to stressors is discussed.

Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 84%

Differential Impact of Audiogenic Stressors on Lewis and Fischer Rats: Behavioral, Neurochemical, and Endocrine Variations

Michaud

McLean

Keith

et al. 2003

“…When tissue levels of monoamines are measured in KO mice at a time of stereotypic activation, 5-HT metabolism is increased in all three brain regions. By contrast, in WT animals, OF exposure alters DA levels in frontal cortex and 5-HIAA is increased only in frontal cortex and caudate putamen which may reflect stress of the test conditions (Berridge and Dunn, 1989;Ge et al, 1997). Hence, in KO mice interactions between dopaminergic and serotonergic neurotransmission are perturbed.…”

Section: Discussionmentioning

confidence: 91%

Novelty Seeking and Stereotypic Activation of Behavior in Mice with Disruption of the Dat1 Gene

Pogorelov

Rodriguiz

Insco

et al. 2005

137

116

Disruption of the dopamine (DA) transporter (Dat1) gene in mice leads to a 50% reduction or complete elimination of Dat1 expression in striatum of respective heterozygous (HZ) and knockout (KO) mice. Compared to wild-type (WT) controls, extracellular DA is increased approximately two-and five-fold in the mutants. Although open field (OF) activity is similar for WT and HZ animals, it is enhanced for KO mice. The purpose of the present investigations was to study spontaneously emitted behaviors and to determine the behavioral and neurochemical mechanisms that may contribute to the hyperactivity of KO animals. Heterozygotes are less anxious than other genotypes and they engage in novelty-seeking behaviors that include increased time spent in the center of the OF, enhanced investigation of objects, and augmented free exploration of a novel environment. By comparison, KO mice display neophobia when initially exposed to novel conditions. Over time the anxiety-like response habituates and behaviors become activated and stereotyped; these responses are unrelated to exploration or novelty seeking. No alterations in extracellular DA levels or tissue contents from several brain regions are detected at the time of stereotypic activation of KO mice. By contrast, this behavior is accompanied by changes in serotonin metabolism in basal ganglia. This feature may contribute to the behavioral inflexibility of KO mice in different experimental contexts. Collectively, these findings suggest that disruption of the Dat1 gene in mice leads to two different phenotypes; one related to anxiety-reducing and novelty seeking, while the other has some homology to disorders with a stereotypical-perseverative spectrum.

“…Previous studies have shown that ICV infusions of this compound blocked the effect of acute stress on various behavioral measures at doses ranging from 5 to 50 μg (Krahn et al, 1986;Kalin et al, 1988;Berridge and Dunn, 1989;Cole et al, 1990;Nawata et al, 2012). In the present study, we infused 30 μg/4 μl, dissolved in distilled water.…”

Section: Drugs and Microinfusion Proceduresmentioning

confidence: 85%

Perturbations in Effort-Related Decision-Making Driven by Acute Stress and Corticotropin-Releasing Factor

Bryce

Floresco

2016

Acute stress activates numerous systems in a coordinated effort to promote homeostasis, and can exert differential effects on mnemonic and cognitive functions depending on a myriad of factors. Stress can alter different forms of cost/benefit decision-making, yet the mechanisms that drive these effects remain unclear. In the present study, we probed how corticotropin-releasing factor (CRF) may contribute to stress-induced alterations in cost/benefit decision-making, using an task where well-trained rats chose between a low effort/ low reward lever (LR; two pellets) and a high effort/high reward lever (HR; four pellets), with the effort requirement increasing over a session (2, 5, 10, and 20 presses). One-hour restraint stress markedly reduced preference for the HR option, but this effect was attenuated by infusions of the CRF antagonist, alpha-helical CRF. Conversely, central CRF infusion mimicked the effect of stress on decision-making, as well as increased decision latencies and reduced response vigor. CRF infusions did not alter preference for larger vs smaller rewards, but did reduce responding for food delivered on a progressive ratio, suggesting that these treatments may amplify perceived effort costs that may be required to obtain rewards. CRF infusions into the ventral tegmental area recapitulated the effect of central CRF treatment and restraint on choice behavior, suggesting that these effects may be mediated by perturbations in dopamine transmission. These findings highlight the involvement of CRF in regulating effort-related decisions and suggest that increased CRF activity may contribute to motivational impairments and abnormal decision-making associated with stress-related psychiatric disorders such as depression.