Development of the amygdalohypothalamic projection in the mouse embryonic forebrain

Abstract

The amygdalohypothalamic projection, a major component of the stria terminalis, is involved in the conduction of emotional and olfactory information integrated in the amygdala to the hypothalamus to elicit emotional reactions. Despite the extensive studies on functional aspects of the amygdaloid complex, developmental mechanisms of the amygdala and related structures are still poorly understood. To investigate the development of the amygdalohypothalamic projection in the mouse embryonic brain, carbocyanine dye was applied to the amygdala to label the growing axons anterogradely and to the hypothalamus to label the amygdaloid neurons retrogradely. The initial outgrowth of the stria terminalis was found to be as early as E11.5. The pathway crossed in a saddle over the internal capsule, another prominent connection in the developing forebrain of the mammalian embryo. Bipolar immature neurons were distributed along the stria terminalis at the telencephalo-diencephalic boundary, and the internal capsule was also surrounded by these cells. These cells expressed immunoreactivities to calretinin and the lot-1 antigen which has been shown to be involved in guidance of the developing lateral olfactory tract. Ultrastructural analysis revealed an adherens-like junction between the stria terminalis and the apposed cells, implying contact-mediated guidance. These results suggest that, in the development of the stria terminalis, the axonal outgrowth is guided by a mechanism similar to that of the developing lateral olfactory tract, a major amygdalopetal connection.

Genetic identification of the central nucleus and other components of the central extended amygdala in chicken during development

“…In agreement with this proposal, our tract-tracing experiments showed that many of the subdivisions of the chicken central extended amygdala project to the lateral hypothalamus, a feature typical of the central extended amygdala in different vertebrates (Alheid et al, 1995; Cassell et al, 1999; Aizawa et al, 2004; Moreno and González, 2006; Martínez-García et al, 2007). We discuss the evidence below, first for the lateral region encompassing subdivisions comparable to the central amygdala and intercalated amygdalar cells of mammals (Section “Lateral Region of the Central Extended Amygdala and Surrounding Areas”), and then for the medial region encompassing the BSTL (Section “Medial Part of the Central Extended Amygdala: BSTL”).…”

Development of the mouse amygdala as revealed by enhanced green fluorescent protein gene transfer by means of in utero electroporation

“…4c,d). These findings suggest that the trajectory labeled at E11 is the efferent trajectory originating from the Ce that we previously demonstrated by the DiI‐tracing method (Aizawa et al,2004). The trajectory labeled at E12, on the other hand, is thought to be mainly the afferent trajectory originating from the BNST, because the connection between the medial part of the Ce and the BNST has been reported to be reciprocal (Dong et al,2001a,b; Dong and Swanson,2004) and the time of neurogenesis of the BNST, especially the caudal part, is later than that of the amygdalar Ce (Bayer1987).…”

Insulin signaling in the hippocampus and amygdala regulates metabolism and neurobehavior

“…The sympathetic nervous system (SNS) innervates the liver and controls hepatic glucose production. Our data indicate that the amygdala may play a role in the regulation of hepatic glucose metabolism and, eventually, systemic glucose levels, directly or through other brain regions with which it has projections, such as the hypothalamus (43). Indeed, it has been shown that insulin injected in the central amygdala activates neuronal populations in regions of the hypothalamus (44) known to affect the autonomic output to the liver.…”