The Extended Amygdala and Salt Appetite

Abstract

Both chemo- and mechanosensitive receptors are involved in detecting changes in the signals that reflect the status of body fluids and of blood pressure. These receptors are located in the systemic circulatory system and in the sensory circumventricular organs of the brain. Under conditions of body fluid deficit or of marked changes in fluid distribution, multiple inputs derived from these humoral and neural receptors converge on key areas of the brain where the information is integrated. The result of this central processing is the mobilization of homeostatic behaviors (thirst and salt appetite), hormone release, autonomic changes, and cardiovascular adjustments. This review discusses the current understanding of the nature and role of the central and systemic receptors involved in the facilitation and inhibition of thirst and salt appetite and on particular components of the central neural network that receive and process input derived from fluid- and cardiovascular-related sensory systems. Special attention is paid to the structures of the lamina terminalis, the area postrema, the lateral parabrachial nucleus, and their association with the central nucleus of the amygdala and the bed nucleus of the stria terminalis in controlling the behaviors that participate in maintaining body fluid and cardiovascular homeostasis.

The central and basolateral nuclei of the amygdala exhibit opposite diurnal rhythms of expression of the clock protein Period2

“…These include, but are not limited to, the striatum, paraventricular hypothalamic nucleus, arcuate nucleus, preoptic area, and olfactory bulbs (11-17). The study of clock genes in these and other functionally defined brain regions may help to determine how the SCN clock controls specific circadian rhythms and, importantly, may contribute to an understanding of how diverse experiences and pathological conditions can affect circadian rhythms downstream from the SCN clock.We found recently that the clock protein Period2 (PER2) is expressed rhythmically in the oval nucleus of the bed nucleus of the stria terminalis (BNST-OV) (18), a region of the limbic forebrain known to be involved in the regulation of behavioral, autonomic, and endocrine responses to motivationally and emotionally significant stimuli (19,20). This rhythm was synchronous with the PER2 rhythm in the SCN and was maintained in constant dark.…”

“…We found recently that the clock protein Period2 (PER2) is expressed rhythmically in the oval nucleus of the bed nucleus of the stria terminalis (BNST-OV) (18), a region of the limbic forebrain known to be involved in the regulation of behavioral, autonomic, and endocrine responses to motivationally and emotionally significant stimuli (19,20). This rhythm was synchronous with the PER2 rhythm in the SCN and was maintained in constant dark.…”

The Subfornical Organ is the Primary Locus of Sodium-Level Sensing by NaxSodium Channels for the Control of Salt-Intake Behavior

“…This strongly indicates that Na x in the SFO is the primary site of sodium-level sensing and for the control of salt-intake behavior. It is known that the SFO has efferents to integrative and effector motor regions in the brain, including the amygdaloid nucleus (Johnson et al, 1999;McKinley et al, 2003). These neural pathways would be directly responsible for the control of the Naand water-intake behavior.…”

Oxytocinergic and serotonergic systems involvement in sodium intake regulation: satiety or hypertonicity markers?

“…The present data seem to indicate that the BNST and CeA make roughly equal contributions to these forms of experimentally induced salt intake. In addition, the amygdala and bed nucleus of the stria terminalis also receive afferent input from the structures of the lamina terminalis (26,32) as well as visceral and somatic inputs via LPBN (21,58). According to the latter, there was a major increase in c-fos expression in depleted animals with access to 2% NaCl compared with the 0.9% NaCl access group, suggesting that signals coming from osmo-sodium receptors arrive and are integrated in these neuronal groups of the extended amygdala.…”