Articles

Article

Original

Exp Neurobiol 2007; 16(2): 89-96

Published online December 31, 2007

© The Korean Society for Brain and Neural Sciences

Increased IL-1Ղ and Tyrosine Hydroxylase Immunoreactivity by Acute and Repeated Foot Shock Stress in the Locus Coeruleus

Eun-Yee Jung, Kwang-Ho Pyun and Insop Shim*

Department of Integrative Medicine, The Catholic University of Korea College of Medicine, Seoul 137-701, Korea

Correspondence to: *To whom correspondence should be addressed.
TEL: 82-2-590-2971, 2972, FAX: 82-2-592-6359
e-mail: ishim@catholic.ac.kr

Abstract

The locus-coeruleus (LC), which is almost composed of noradrenergic neurons, plays an important role in modulating the central stress response. It has been well known that stress causes an increase in the expression of tyrosine hydroxylase (TH), the rate-limiting enzyme for NE synthesis, in the LC and may also influence brain cytokine such as interleukin-1Ղ (IL-1Ղ) expression. However, relevance of IL-1Ղ, the proinflammatory cytokine, and TH in the LC following exposure of stress has not been studied. The aim of the present study was to determine possible involvement of TH and IL-1Ղ in the stress response in the LC. Exposure to acute electric foot shock (ten, 0.8 mA for 5 sec, foot-shocks) resulted in increased IL-1Ղ in the LC, evidenced by increased IL-1Ղ double labeled cells in TH immunoreactive cells, which were similar to those observed after treatment with lipopolysaccharide (LPS), compared with the non-treated group. Repeated daily exposure to the same foot shock stress tended to further increase IL-1Ղ in the TH immunoreactive cells in the LC. The present results demonstrated that acute physical stress stimulated IL-1Ղ production in the NE cells and that repeated stress may potentiate stress-induced IL-1Ղ production in the NE cells in the LC. These findings raise the possibility that NE neurotransmitter system is modulated by IL-1Ղ in the LC under conditions of acute and repeated foot shock stress.

Keywords: foot Shock Stress, locus-coeruleus (LC), interleukin-1Ղ, (IL-1Ղ,), tyrosine hydroxylase (TH), immunoreactivity