[Thymus hormones--precursors of new psychoneuromodulatory peptides]. / Timusnye gormony--predshestvenniki novykh psikhoneiromoduliruiushchikh peptidov.

The influence of thymic hormone's short fragments: thymopentin or T-5 (RKDVY), RKD and SKD, on behaviour and neurochemical processes (contents of GABA and monoamines in the brain and adrenals, plasma corticosterone), was investigated. The 100 and 500 micrograms/kg doses i.p. prevented alterations in rat's brain GABA content and plasma corticosterone level, as well as elicited anxiolytic activity in a conflict test. T-5 exerted antidepressant activity, too. SKD potentiated the haloperidol-induced catalepsy. The data obtained suggest a multicomponent (CNS-activating and inhibiting) mechanism of action of the thymic hormone fragments. These fragments seem to be formed endogenously during thymic hormone bioprocessing and may act as regulatory neuropeptides.

[Neuroimmunoregulatory properties of short protein fragments in rats exposed to immobilization stress]. / Neiroimmunoreguliruiushchie svoistva korotkikh fragmentov belkov v usloviiakh immobilizatsionnogo stressa u krys.

The influence of short protein fragments on immobilization stress-induced alterations in neuroendocrine and immune systems (catecholamine content in the striatum, hypothalamus and adrenals, serum corticosterone concentration, specific antibody producing activity) was investigated. Immunoglobulin G fragments--tuftsin, rigin, polar amino acid set--polarin and thymus hormone fragment--thymopoetin, as well as substance P (as reference drug) were administered intraperitoneally at doses of 100 and 500 micrograms/kg 30 min before exposure to stress. Rigin and thymopentin showed high stress-protective activity. It is suggested that similar protein fragments, being endogenously formed, may play a regulating role in neuroimmunological homeostasis during exposure to stress.