Proliferation of arterial smooth muscle cells incubated in serum from brain-stimulated rats.

Platelet deficient serum prepared from rats subjected to acute electrical stimulation of the lateral hypothalamus demonstrated mitogenic activity when added to incubating media supporting growth of homologous arterial smooth muscle cells in vitro. This activity did not appear to be related to the presence of platelet-derived growth factor, hyperlipidemic lipoproteins or increased amounts of insulin. Plasma arginine vasopressin concentration was elevated in these animals, but further investigation is required to determine if this elevation is causally related. Since hypothalamic stimulation is also associated with severe endothelial injury in vivo, the mitogenic activity of the blood of such animals could induce proliferation of SMC which have migrated into the arterial intima. Such features have been observed in chronically stimulated animals and may be of relevance for the role of neural factors in atherogenesis.