Semaphorin-3A Inhibits Proliferation, but Does Not Affect Apoptosis of Mouse Thymocytes In Vitro.

Neuronal factor semaphorin-3A is viewed as immune suppressant of peripheral T lymphocytes, but it can also negatively affect activity of the thymus, the central organ of the immune system. The study examined the effects of this factor on proliferative activity and apoptosis of mouse thymocytes in vitro. Semaphorin-3A inhibited spontaneous and mitogen-stimulated proliferative activity of thymocytes producing no effect on the development of apoptosis in these cells. Flow cytometry revealed expression of semaphorin-3A receptors neuropilin-1 and plexin-A1 on thymocyte membranes. Approximately 13% thymocytes simultaneously expressed both receptors. The study suggests that semaphorin-3A, which is constitutively synthesized in thymic stroma in vivo, can play the role of inhibitory factor during thymocyte maturation.

Modification of Anxious Behavior after Psychogenic Trauma and Treatment with Galanin Receptor Antagonist.

Effects of blockage of central galanin receptors on anxiety manifestations were studied in rats with psychogenic trauma. Psychogenic trauma was modeled by exposure of a group of rats to the situation when the partner was killed by a predator. Antagonist of galanin receptors was intranasally administered before stress exposure. Animal behavior was evaluated using the elevated-plus maze test, free exploratory paradigm, and open-field test. Psychogenic trauma was followed by an increase in anxiety level and appearance of agitated behavior. Blockage of galanin receptors aggravated behavioral impairment, which manifested in the pathological anxious reactions - manifestations of hypervigilance and hyperawareness. The results suggest that endogenous pool of galanin is involved into prevention of excessive CNS response to stressful stimuli typical of posttraumatic stress disorder.

The role of the neuropeptide galanin in forming type-specific behavioral characteristics.

Intranasal administration of a galanin receptor blocker to rats was found to change their behavioral type on being placed in an unfamiliar environment, with decreases in movement and investigative activity and increases in the level of anxiety in the open field test. The basal level of expression of the galanin precursor mRNA in the anterior hypothalamus was significantly higher in rats with the active type of behavior in the open field test. In conditions of galanin receptor blockade, there was also a faster increase in the serum corticosterone level in response to a stress situation (forced swimming test), which was accompanied by a reduction in the immobilization time. These data support the involvement of galanin in the formation of individual-typological behavioral characteristics and demonstrate its important role in adaptation to stress.

The psychomodulatory action of subpyrogenic doses of interleukin-1beta in conditions of chronic administration to rats.

The effects of interleukin-1beta at low, subpyrogenic doses on behavior were studied in rats. Signs of increased anxiety were evident by day 5 of treatment courses. These results provide evidence supporting the role of proinflammatory cytokines in the pathogenesis of emotional disorders.

Effect of VEGF on mouse thymocyte proliferation and apoptosis in vitro.

Vascular endothelial growth factor is not only angiogenic, but also immunoregulatory factor. For evaluation of the possibility of its direct interaction with mouse thymocytes we studied the effect of vascular endothelial growth factor on proliferation and apoptosis of thymocytes and expression of genes for the corresponding receptor on these cells. Vascular endothelial growth factor modulated mitogen-induced proliferation of thymocytes and stimulated spontaneous apoptosis in intact thymus cells. Thymocytes express mRNA of type 2, but not type 1 vascular endothelial growth factor receptors.

Antipyretic effect of neuropeptide galanin in endotoxin-induced fever.

Neuropeptide galanin produces a antipyretic effect in experimental pyrogenic reaction induced by intraperitoneal injection of lipopolysaccharide. Central intracerebroventricular injection of 100 ng galanin significantly attenuated, but did not completely abolish fever. Central galanin injection potentiated endotoxin-induced activation of the noradrenergic system and blocked activation of the serotoninergic system of the anterior hypothalamus.