The hypothalamic lateral tuberal nucleus: normal anatomy and changes in neurological diseases.

The lateral tuberal nucleus is a circumscribed cell mass in the lateral posterior part of the hypothalamus, containing about 60000 neurons. It can be recognized in man and higher primates, probably not in other mammals. Its neurotransmitter content and connections with other parts of the brain are as yet unknown. But receptors for corticotropin-releasing factor and somatostatin, as well as muscarinic cholinergic receptors, benzodiazepine receptors and N-methyl-D-aspartate receptors have been localized within the confines of the nucleus. The lateral tuberal nucleus is affected in a number of human neurodegenerative diseases. Changes in Parkinson's disease are the least obvious: Lewy bodies appear in small amounts, the majority of them apparently lying outside a neuronal perikaryon. Neuronal loss does not occur. In Alzheimer's disease the number of neurons seems to be normal as well. Rarely silver staining tangles occur, and the deposition of A4/beta-protein in amorphous plaques is moderate. Yet, NTL neurons stain heavily in Alz-50 immunocytochemistry, while Alz-50 staining in NTL neurites is very dense. These changes are interpreted as indicating early Alzheimer-related pathology. In Huntington's disease the NTL loses neurons. This loss is related to the severity of the disease: patients who first display motor disturbances at an early age will lose more neurons than those who start later. The relation between these clinical characteristics and the severity of neuronal loss is such, that it seems likely that NTL neurons possess a special vulnerability for the effect of the Huntington gene. This could be related to their NMDA-receptor content. It is hypothesized that the NTL is involved in a neuronal network that regulates feeding and metabolism. NTL pathology may explain the peculiar catabolic state of many patients with Alzheimer's or Huntington's diseases.