TNF-alpha expressed in the brain of transgenic mice lowers central tyroxine hydroxylase immunoreactivity and alters grooming behavior.

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine involved in a wide range of biological effects both in physiological and non-physiological conditions. It is also produced in the central nervous system (CNS) where it has been implicated in reparative processes after traumatic injuries and in CNS demyelination, neurodegeneration and inflammation. Using transgenic mice (Tg-m) expressing TNF-alpha specifically in the CNS, we showed that the overexpression of this cytokine reduced tyroxine hydroxylase immunoreactivity (TH-ir) in the caudate-putamen and in the dorsomedial hypothalamic areas and impaired grooming behavior. We also showed that this behavior is increased following anti-nerve growth factor injection. These findings support the hypothesis, proposed by others, that TNF-alpha is involved in the degenerative processes which occur in Parkinson's disease.