Prevention of stress-induced involution of the thymus in rats by substance P (SP1-11) and its N-terminal fragment SP1-4.

Selye found that in response to different stressors the body reacts with a characteristic stress syndrome: adrenal enlargement, gastrointestinal ulcera, and thymicolymphatic involution. In this paper we demonstrate that i.p. injected Substance P (SP) can prevent stress-induced involution of thymus in Wistar rats. This protecting effect on the immune system of SP, in addition to the "normalizing" effects of this peptide on stress-induced disorders in vegetative and central functions first described by Oehme and co-workers and Hecht and co-workers is a new hint to the function of SP as an "anti-stress" agent. The mode of action of the anti-stress effect of SP in adrenals as well as in the thymus is discussed. It is suggested that the anti-stress effect of SP1-11 and its N-terminal fragment SP1-4 is mediated by specific receptors in adrenals and/or thymus which are different from the so called SP-P and SP-E receptors.