Pavlovian conditioning of LPS-induced responses: Effects on corticosterone, splenic NE, and IL-2 production

• Published in: Physiology & behavior Vol. 59; no. 6; pp. 1103 - 1109
• Main Authors: Janz, Loren J., Green-Johnson, Julia, Murray, Linda, Vriend, Catherine Y., Nance, Dwight M., Greenberg, Arnold H., Dyck, Dennis G.
• Format: Journal Article
• Language: English
• Published: Cambridge Elsevier Inc 01-06-1996; New York, NY Elsevier
• Subjects: Animals; Biochemistry and metabolism; Biological and medical sciences; Central nervous system; Conditioning, Classical - physiology; Corticosterone; Corticosterone - biosynthesis; Dose-Response Relationship, Drug; Drinking Behavior - drug effects; Fundamental and applied biological sciences. Psychology; IL-2; Interleukin-2 - biosynthesis; Lipopolysaccharide; Lipopolysaccharides - pharmacology; Male; Norepinephrine; Norepinephrine - biosynthesis; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Saccharin - pharmacology; Spleen - drug effects; Spleen - metabolism; Sweetening Agents - pharmacology; Taste - drug effects; Taste aversion; Vertebrates: nervous system and sense organs; Taste aversion; Lipopolysaccharide; IL-2; Norepinephrine; Corticosterone; Rat; Rodentia; Nervous system; Catecholamine; Glucocorticoid; Vertebrata; Mammalia; Interleukin 2; Adrenal hormone; Taste; Conditioned aversion; Immune system
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/0031-9384(95)02171-X

The present study used a taste aversion paradigm to condition lipopolysaccharide (LPS)-induced suppression of splenic lymphocyte interleukin-2 (IL-2) production, with concurrent measurement of corticosterone production and splenic norepinephrine (NE) content. In training, two groups of rats received saccharin and IP LPS in a paired (P) manner and a third group in a specifically unpaired (U) manner. In the test, the unpaired group (group U) and one of the paired (group P) groups were reexposed (R) to the cue and the other not (NR). An additional group controlled for the effects of cues (conditional stimulus) and fluid deprivation (negative control; NC). A robust taste aversion in the P-R group was accompanied by suppression of IL-2 production, reduced splenic NE content, and elevated corticosterone production, relative to combined controls (i.e., groups U-R, P-NR,and NC). The conditioned modulation of IL-2 secretion, along with the concomitant alteration of adrenocortical and sympathetic mediators, supports the involvement of bidirectional central nervous-immune system pathways in this paradigm.