Regional, cellular, subcellular distribution of neurospecific protein-hormonal complexes

A sensitive radioimmunological assay (RIA) has been developed to detect the tissue specificity and subcellular localization of three specific protein-hormonal complexes (PHC) of the hypothalamus which have a regulatory function in the brain and visceral organs. Using the highly specific rabbit antisera to beef PHC an order of increasing immunoreactivity in different areas of CNS is as follows: hypothalamus, cerebellum, occipital cortex. The PHC-like immunoreactivity (IR) is found in the neurosecretory granules of the hypothalamo-neurohypophyseal system (about 30%) and in the synaptosomal fraction (70%). In the myelin, mitochondrial and nuclear fractions the PHC-like IR is not revealed. IR of PHC is 1000-fold higher in the brain than in visceral organs (heart, skeletal muscles, adrenals, pancreas and blood serum). A possible role of the PHC as markers of the neuroendocrine cells is discussed.