The Journal of Neuroscience, June 1, 1999, 19(11):4533-4543
T-Lymphocyte Activation Increases Hypothalamic and Amygdaloid
Expression of CRH mRNA and Emotional Reactivity to Novelty
Alexander W.
Kusnecov1,
Rumei
Liang2, and
Galina
Shurin3
1 Department of Psychology, Rutgers University, New
Brunswick, New Jersey 08901, and Departments of 2 Pathology
and 3 Surgery, University of Pittsburgh School of Medicine,
University of Pittsburgh, Pittsburgh, Pennsylvania 15238
Stimulation of T-cells with staphylococcal enterotoxin B (SEB)
significantly elevates interleukin-2 (IL-2) and contemporaneous activation of the hypothalamic-pituitary-adrenal (HPA) axis and c-fos in the paraventricular nucleus (PVN) of BALB/cByJ
mice. Such neural signaling may promote cognitive and emotional
adaptation before or during infectious illness. Because
corticotropin-releasing hormone (CRH) is an anxiogenic neuropeptide
that may mediate the stressor-like effects of immunological stimuli, we
measured neuronal CRH mRNA alterations in mice challenged with SEB.
Increased CRH mRNA levels were observed in the PVN and central nucleus
of the amygdala (ceA) 4-6 hr after SEB administration. This was
associated with plasma ACTH increases, which could be abrogated by the
systemic administration of anti-CRH antiserum. Additional experiments
did not support a role for IL-2 or prostaglandin synthesis in
activating the HPA axis. Behavioral experiments testing for conditioned
taste aversion did not confirm that SEB challenge promotes malaise. However, consistent with the notion that central CRH alterations induced by SEB may affect emotionality (e.g., fear), SEB challenge augmented appetitive neophobia in a context-dependent manner, being
marked in a novel and stressful environment. It is hypothesized that
immunological stimuli generate a cascade of events that solicit integrative neural processes involved in emotional behavior. As such,
these data support the contention that affective illness may be
influenced by immunological processes and the production of cytokines
and are consistent with other evidence demonstrating that
autoimmune reactivity is associated with enhanced emotionality.
Key words:
T-lymphocytes; corticotropin-releasing hormone; staphylococcal enterotoxin B; adrenocorticotropic hormone; psychoneuroimmunology; emotion; neophobia; interleukin-2; cytokines; prostaglandins; stress; amygdala; hypothalamus
Copyright © 1999 Society for Neuroscience 0270-6474/99/19114533-11$05.00/0