Neurohormones in the Hypothalamo-Hypophysial System in Senile Dementia of the Alzheimer Type

Abstract

Oestrogen-stimulated neurophysin (ESN), oxytocin (OXY), nicotine-stimulated neurophysin (NSN), arginine vasopressin (AVP), somatostatin (SS) and growth hormone-releasing hormone (GHRH) were measured in post-mortem dorsal and basal hypothalamus and pituitary stalk from cases of senile dementia of the Alzheimer type (SDAT) and age-matched controls and in pituitary stalk from cases of mixed SDAT/cerebrovascular dementia. The 6 neurohormones were also measured in pituitary glands from cases of SDAT, other dementias and age-matched controls. ESN, OXY, NSN and AVP were unaltered in the hypothalamus and pituitary stalk of the SDAT cases and in the pituitary stalk of the mixed SDAT/cerebrovascular cases. The concentrations of NSN and AVP were lower in pituitary glands from 8 controls who were terminally ill than in 5 controls who had died suddenly. Between-group comparisons of terminally ill cases showed that ESN, OXY, NSN and AVP were reduced in pituitary glands from 12 SDAT cases and that NSN and AVP were reduced in glands from 9 cases of other dementias. SS and GHRH were unaltered in the hypothalamus, and GHRH was unaltered in the pituitary stalk, of 19 SDAT cases compared with 18 controls. Reduced levels of SS in the pituitary stalk of the SDAT group could be attributed to terminal illness, since terminally ill controls had lower pituitary stalk SS concentrations than controls who had died suddenly. The major form of SS in the hypothalamus was somatostatin-14, whereas the major form in pituitary stalk was somatostatin-28, suggesting that somatostatin-28 may have a specific role in the control of hormone secretion from the adenohypophysis. Our ESN, OXY, NSN and AVP data suggest that whilst synthesis and transport of the hypothalamo-neuro-hypophysial hormones are unaffected in SDAT, storage of these hormones in the neurohypophysis may be reduced in SDAT and other dementias.