Damage to the central amygdala (CeA) induces differential c-fos expresssion in the parabrachial and paraventricular nucleus in the water-deprivation-partial rehydration protocol

Damage to the CeA reduces 0.3 M NaCl intake that follows 36 h of water deprivation and partial volume rehydration with water for 2 h (WD-PR protocol). In the present work, we investigated the effect of CeA damage (CeAX) on central neuronal c-fos expression at the end of the WD-PR. Adult Sprague-Dawley rats ( n=6), either hydrated or at the end of a WD-PR, were anesthetized and had their brains removed for immunohistochemistry specific for c-fos protein. The groups were devided into sham lesion, bilateral CeA lesion (CeAXb), unilateral CeA lesion (CeAXu) and misplaced bilateral lesion (CeAXm). The c-fos expression (number of positive cells/10 −2 mm 2) averaged for medial parabrachial nucleus (MPBN) and parvocellular portion of the hypothalamic paraventricular nucleus (PVNp) was enhanced in CeAXb (24±3) and CeAXu (18±2, n=3) WD-PR groups compared to shams (7±2) or hydrated CeAXb (3±1). Damage to the CeA did not change c-fos expression in the lamina terminalis or lateral parabrachial nucleus. No alterations occured in CeAXm. The enhanced neuronal activation in PVNp and MPBN might relate to reduced sodium appetite in animals with damage to the CeA. Support: CNPq, FAPESP, Joint UFSCar/UNESP Graduate Program in Physiological Sciences.