Topographic patterns of brain activity in response to swim stress: assessment by 2-deoxyglucose uptake and expression of Fos-like immunoreactivity

Abstract

Alterations in brain activity patterns were assessed in response to swim stress by immunocytochemical detection of Fos-like immunoreactivity (Fos-LI) and high-resolution autoradiographic imaging of 14C-2-deoxyglucose (2-DG) uptake. The stress paradigm investigated was a classic behavioral screen for antidepressant drug activity, the forced swim test. One of the most pronounced effects produced by swim stress was an increase in 2-DG uptake and induction of Fos-LI in a restricted region of the lateral septal nucleus. Specific "limbic" cortical regions, including the medial prefrontal, ventrolateral orbital, and cingulate cortices, also exhibited both increased 2-DG uptake and expression of Fos-LI in response to swim stress. In the hypothalamic paraventricular nucleus of swim-stressed rats, Fos-LI was induced but no change in 2-DG uptake was apparent. Since the specific swim stress protocol used is a behavioral screen for antidepressant drugs, the effects of imipramine on stress-induced alterations in 2-DG uptake and induction of Fos-LI were examined. The stress-induced increase in 2-DG uptake in the lateral septum was blocked by treatment with imipramine, but treatment with imipramine had no effect on induction of Fos-LI in the same region. Neither 2-DG uptake nor Fos-LI expression was altered by imipramine treatment in the cortical regions influenced by swim stress. Administration of imipramine alone under basal conditions produced a robust induction of Fos-LI in the central nucleus of the amygdala and in the dorsal lateral subdivision of the bed nucleus of the stria terminalis. No effect of imipramine treatment on 2-DG uptake was apparent in these latter regions. The results provide insights into topographic patterns of brain activity associated with swim stress and neuroanatomically selective actions of imipramine. The different and complementary information obtained by assessment of Fos-LI and 2-DG uptake illustrates the utility of applying both functional mapping approaches to examine neuroanatomical correlates of behavioral states and drug treatment.

Circuitry Underlying Regulation of the Serotonergic System by Swim Stress

“…The distribution of c-fos immunolabeling in rats subjected to swim stress was similar to that reported previously (Duncan et al, 1993;Cullinan et al, 1996). For example, c-fos-immunoreactive profiles were numerous in the LC, dorsolateral parabrachial nucleus, lateral habenula, paraventricular nucleus of the hypothalamus, and lateral septum of swim-stressed rats.…”

Cognitive Deficits Caused by Late Gestational Disruption of Neurogenesis in Rats: a Preclinical Model of Schizophrenia

“…In normal rats, the forced swim paradigm increases extracellular dopamine in the prefrontal cortex, but not in the nucleus accumbens (Tucci et al, 1994). In addition, the activation of the prefrontal cortex during the task has been established by 2-deoxyglucose experiments (Duncan et al, 1993). If dopamine response in the prefrontal cortex is inhibited (for example, by 6-OHDAinduced dopamine depletion), the animal does not adapt to the situation, but keeps swimming/struggling (Ravard et al, 1990;Espejo and Minano 1999).…”

Systemic administration of interleukin‐1β activates select populations of central amygdala afferents

“…It has also been implicated as a nucleus involved in cyclic rhythmicity patterns (Watts et al, 1987;Peng et al, 1995). Cells in the PVT are recruited by several different acute stressors, including restraint, forced swim, foot shock, and conditioned fear (Duncan et al, 1993;Beck and Fibiger, 1995;Cullinan et al, 1995;Bhatnagar and Dallman, 1998;Bubser and Deutch, 1999;Bhatnagar et al, 2000), and at least one study has demonstrated that the PVT is a source of stress-activated afferents to the amygdala (Bubser and Deutch, 1999). Interestingly, there is recent evidence to suggest that the PVT is inhibitory to HPA axis function but that this inhibition is only apparent when animals have been subjected to prior chronic stress and probably involves direct PVT inputs to the PVN (Bhatnagar and Dallman, 1998;Bhatnagar et al, 2000).…”