Excitotoxic lesions of the bed nucleus of the stria terminalis (BNST) attenuate the effects of repeated stress on weight gain: evidence for the recruitment of BNST activity by repeated, but not acute, stress

Abstract

Exposure to repeated stress can lead to diverse and widespread behavioral consequences, including reduction in food and water intake and subsequent diminution in weight gain. Many reports have suggested that repeated stress substantially alters the neurochemistry, morphology and physiology of neurons within the bed nucleus of the stria terminalis (BNST). Here we investigate the role of the BNST in mediating the reduced weight gain observed during repeated stress. Rats exposed to a one-week variate stress paradigm exhibited a reduction in weight gain over the course of the 7-day paradigm. Excitotoxic lesions to a subregion of the anterolateral BNST containing the oval nucleus had no effects early in the 7-day paradigm, but significantly attenuated the effects of repeated stress on weight gain by the last day of stress. These data suggest that at least two mechanisms mediate the effects of stress on body weight gain, and that when stressor exposure becomes repeated, the BNST is recruited, worsening the symptoms of stressor exposure.

Figure 1

Above: extent of the smallest (solid) and largest (hatched) anterolataral NMDA excitotoxic BNST lesions accepted for analysis. Below: a representative excitotoxic BNST lesion visualized using anti-NeuN immunohistochemistry. BNST tissue from a vehicle treated (sham) rat is shown on the left; the same region is shown from an NMDA (lesion) rat on the right.

Figure 2

Above: weight change in rats that received excitotoxic lesions to the BNST 1-week before exposure to the 7-day chronic variate stress procedure. Repeated variate stress significantly reduced weight over the course of the 7 day paradigm. BNST lesions attenuated this effect, but only toward the end of the 7 day period. Below: BNST lesions had no effect on stress-induced weight change from Day 1 to Day 4, but significantly attenuated the effects of stress on weight from Day 4 to Day 8. Ns = non-significant, * = p < 0.05.