The cerebrovascular effects of PRP-1

More than 50 years ago we demonstrated that the neurosecretory NSO and NPV cells of the hypothalamus can produce not only releasing hormones, such as vasopressin and oxytocin, but also hormones that are able to regulate cardiac activity and coronary circulation. Moreover, we showed that 5–6 min after intravenous administration (1 mg/kg) to a cat of a coronarydilatory protein of the hypothalamus that we isolated the blood pressure in the vertebral artery gradually decreased, reaching 20–30 ml of Hg following two or more administrations, thus indicating the reduction of cerebral vessel tonus. These results indicate that the protein we isolated is able to dilate the blood vessels of both the heart and the brain. Later, we isolated these proteins from animal neurohypophysis, which indicates the hormonal nature of these proteins and polypeptides. Moreover, the proline-rich polypeptides PRP-1 (Galarmin) that we isolated and chemically characterized as consisting of 15 amino-acid residues, has coronarydilatory properties. It was of great interest to investigate the activity of Galarmin on normal and damaged cerebral blood flow. Our experimental results demonstrated the ability of PRP-1 to repair damaged cerebral blood flow caused by common carotid artery occlusion.