Motor disturbances, cognitive decline and psychiatric symptoms are considered as the key symptoms of Huntington__s disease (HD). Yet, other prevalent features include unintended weight loss, sleep... Show moreMotor disturbances, cognitive decline and psychiatric symptoms are considered as the key symptoms of Huntington__s disease (HD). Yet, other prevalent features include unintended weight loss, sleep and circadian disturbances and autonomic nervous system dysfunction. The nature of these features supports a pivotal role of the hypothalamus in the HD disease process. In this thesis data is presented from immunocytochemical and in situ hybridization studies demonstrating substantial pathology in hypothalamic neuropeptide expression in HD patients. Main findings include neuropeptide changes in the suprachiasmatic nucleus, the body__s master clock, that will likely be responsible for disruption of 24h circadian rhythmicity. Secondly, the neuronal histaminergic system is hyperactive at both the level of the hypothalamic tuberomamillary nucleus as well as in the cerebral neocortex. These changes could partly explain weight loss and cognitive decline in patients. The expression of neuropeptides in the hypothalamic paraventricular and infundibular nuclei, however, seems to be relatively unaffected by the HD disease process. Finally, a discrepancy between mRNA expression and protein expression of many hypothalamic neuropeptides was observed that can be partly explained by a decrease of prohormone convertase expression. Interestingly, hypothalamic changes in existing HD transgenic rodent models are largely non-representative of hypothalamic changes in HD patients. Show less
