Functional and morphological status of hypothalamic suprachiasmatic nucleus in primary hypertension: Relation to disturbances in diurnal rhythms of hemodynamics

Vasoactive intestinal polypeptide (VIP)-, neurotensin (NT)- and vasopressin (VP)- synthesizing neurons in hypothalamic suprachiasmatic nucleus - the p acemaker of diurnal rhythm of the body - were studied immunohistochemically in persons with proven history of primary hypertension who died of brain h emorrhage or acute heart failure. Quantitative analysis and comparison with items from normotensive individuals showed that in hypertensives the numbe r of neurons in each of these cellular populations was decreased. Decrease in the number of VIP- and NT-synthesizing neurons was considered to be a ca use of disturbed synchronization of diurnal rhythm of physiological process es with regular day-night change, because these neurons received informatio n from special retinal cells. Reduced VP-synthesizing cellular population c ould cause dysinhibition of corticotropin-releasing hormone-synthesizing ne urons in hypothalamic paraventricular nucleus and thus to result in chronic increase of activity of sympathetic nervous system and hypothalamo-pituita ry-adrenal axis.