Exposure to acute stress induces brain interleukin-1b protein in the rat

Peripheral immune stimulation such as that provided by lipo-polysaccharide (LPS) has been reported to increase brain levels of IL-1b mRNA, immunoreactivity, and bioactivity. Stressors produce many of the same neural and endocrine responses as those that follow LPS, but the impact of stressors on brain interleukin-1b (IL-1b) has not been systematically explored. An ELISA designed to detect IL-1b was used to measure levels of IL-1b protein in rat brain. Brain IL-1b was explored after expo-sure to inescapable shock (IS; 100 1.6 mA tail shocks for 5 sec each) and LPS (1 mg/kg) as a positive control. Rats were killed either immediately or 2, 7, 24, or 48 hr after IS. Brains were dissected into hypothalamus, hippocampus, cerebellum, pos-terior cortex, and nucleus tractus solitarius regions. LPS pro-duced widespread increases in brain IL-1b, but IS did not. Adrenal glucocorticoids are known to suppress IL-1b produc