Tumour necrosis factor-alpha and lymphotoxin have opposite effects on sympathetic efferent nerves to brown adipose tissue by direct action in the central nervous system.

Intracerebral injection of recombinant human tumour necrosis factor-alpha (rTNF alpha) decreased, whereas lymphotoxin increased the activity of the sympathetic efferent nerves to interscapular brown adipose tissue (IBAT). The changes in firing rates were accompanied by a significant dose-dependent change in IBAT and rectal temperatures (which were decreased with rTNF alpha and increased with lymphotoxin treatment). These results indicate that rTNF alpha and lymphotoxin act directly in the CNS to modulate the sympathetic outflow to IBAT. The opposite effects of the two peptides also suggest that in the CNS, separate receptor systems exist.