The lateral septum (LS) is a forebrain structure that has been implicated in a wide range of behavioral and physiological responses to stress. However, the specific populations of neurons in the LS that mediate stress responses remain incompletely understood. Here, we show that neurons in the dorsal lateral septum (LSd) that express the somatostatin gene (hereafter, LSd Sst neurons) are activated by diverse stressors. Retrograde tracing from LSd Sst neurons revealed that these neurons are directly innervated by neurons in the locus coeruleus (LC), the primary source of norepinephrine well-known to mediate diverse stress-related functions in the brain. Consistently, we found that norepinephrine increased excitatory synaptic transmission onto LSd Sst neurons, suggesting the functional connectivity between LSd Sst neurons and LC noradrenergic neurons. However, optogenetic stimulation of LSd Sst neurons did not affect stress-related behaviors or autonomic functions, likely owing to the functional heterogeneity within this population. Together, our findings show that LSd Sst neurons are activated by diverse stressors and suggest that norepinephrine released from the LC may modulate the activity of LSd Sst neurons under stressful circumstances.

The receptor for advanced glycation end products (RAGE) has been reported to have a pivotal role in the pathogenesis of Alzheimer's disease (AD). This study investigated RAGE levels in the hippocampus and cortex of a triple transgenic mouse model of AD (3xTg-AD) using western blotting and immunohistochemical double-labeling to assess cellular localization. Analysis of western blots showed that there were no differences in the hippocampal and cortical RAGE levels in 10-month-old adult 3xTg-AD mice, but significant increases in RAGE expression were found in the 22- to 24-month-old aged 3xTg-AD mice compared with those of age-matched controls. RAGE-positive immunoreactivity was observed primarily in neurons of aged 3xTg-AD mice with very little labeling in non-neuronal cells, with the notable exception of RAGE presence in astrocytes in the hippocampal area CA1. In addition, RAGE signals were co-localized with the intracellular amyloid precursor protein (APP)/amyloid beta (Abeta) but not with the extracellular APP/Abeta. In aged 3xTg-AD mice, expression of human tau was observed in the hippocampal area CA1 and co-localized with RAGE signals. The increased presence of RAGE in the 3xTg-AD animal model showing critical aspects of AD neuropathology indicates that RAGE may contribute to cellular dysfunction in the AD brain.
Advanced Glycosylation End Product-Specific Receptor ; Alzheimer Disease/genetics/*metabolism ; Amyloid beta-Peptides/metabolism ; Animals ; Astrocytes/*metabolism ; CA1 Region, Hippocampal/growth & development/metabolism/pathology ; Humans ; Mice ; Mice, Transgenic ; Neurons/*metabolism ; Receptors, Immunologic/genetics/*metabolism ; tau Proteins/genetics/metabolism