The origin of cerebrospinal fluid somatostatin: hypothalamic or disperse central nervous system secretion?

The present study deals with the origin of somatostatin in cerebrospinal fluid. Two groups of experiments were performed: (1) Diagnostic lumbar puncture was performed in 37 patients admitted for various neurological diseases. Immunological determination of albumin and gamma-globulin, and radioimmunological analysis of somatostatin in successive cerebrospinal fluid taps demonstrated that while the protein concentration was approximately 20% lower in the 11th ml compared to the 1st ml drawn, the somatostatin concentration was constant. (2) Intravenous arginine infusion (30 G/30 min) induced identical patterns of plasma growth hormone in 8 patients with multiple sclerosis in relapse, in 6 patients with multiple sclerosis in the stable phase, and in 7 patients in whom no neurological disease was eventually diagnosed. Cerebrospinal fluid somatostatin was significantly lower in the patients with multiple sclerosis in relapse than in the two other groups, while cerebrospinal fluid growth hormone concentration was identical. There was no correlation between basal or arginine provoked plasma growth hormone and the cerebrospinal fluid content of somatostatin. The results indicate that cerebrospinal fluid somatostatin is released dispersely from the central nervous system including the spinal cord - and that it offers no indication of the activity or tone of hypothalamic growth hormone release inhibiting control of the pituitary gland.