Lateral Septum Somatostatin Neurons are Activated by Diverse Stressors

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.

Spontaneous Hemarthrosis of the Knee in the Elderly

The etiology of spontaneous hemarthrosis of the knee joint in elderly pattents is still unknown. This report discusses seven spontaneous hernarthroses, three that were managed witla conservative measures such as aspiration, rest and knee immobilization because of poor general condition and four in which arthroscopic evaluation and treatment were performed. These patients were elderly indi.viduals without an obvious history of trauma. The roentgenograms of each involved knee demonstrated degenerative osteoarthritic changes of knee joint. Arthroscopic examination revealed denuded articular cartilage and subchondral bone exposure in four operative cases and degenerative meniscal tear in one case of four. These patients underwent mthroscopic debridement and did not experience recurrenees of the hemarthrosis. We think that the origin of the bleeding was most likely from the subchondral cancellous bone which was exposed due to degenerative change of the knee joint and the senile changes of the vessels around the knee joint with aging process may contribute the spontaneous bleeding into the knee joints.