Reduced preference for sucrose in autoimmune mice: a possible role of interleukin-6.
In a continuous one-bottle sucrose intake test, 4-month-old autoimmune MRL-Ipr mice show a shift to the right along the X-axis of the concentration-intake function, compared to congenic MRL +/+ controls. Using a brief (60-min) and a continuous (48-h) two-bottle test, the present report examines potential factors that could account for the reduced responsiveness to a palatable stimulus. Study 1 examines whether preference for sucrose is associated with age, changes in food/water intake, or impaired renal function. Reduced preference for sucrose was observed in 5-6-week-old MRL-Ipr males, although food/water intake or blood creatinine levels did not differ from control values. Immunosuppressive treatment abolished this deficit, suggesting a role of immune factor(s). Study 2 tests the hypothesis that chronic upregulation of the neuroactive cytokine interleukin-6 (IL-6), reported to occur from 3 weeks of age in young MRL-Ipr mice, reduces preference for sucrose. Sustained administration of IL-6 was produced by infecting healthy MRL +/+, C3H.SW and Balb/C mice with adenovirus vector carrying cDNA for murine IL-6. This resulted in high serum IL-6 levels over 5 days, a rapid decline in preference for sucrose and low blood glucose levels. The results from Study 1 indicate that impaired sensitivity to sucrose in MRL-Ipr mice can be detected before autoimmune disease is florid in MRL-Ipr mice. The results from Study 2 are consistent with altered motivation/emotional states after infection, and point to sustained IL-6 production as an early mechanism in behavioral alterations during chronic autoimmune/inflammatory conditions.
Sakić
B
B
Department of Psychiatry, McMaster University, Hamilton, Ontario, Canada.
Szechtman
H
H
Braciak
T
T
Richards
C
C
Gauldie
J
J
Denburg
J A
JA
D000375:Aging / Q000502:physiology; D000818:Animals; D001327:Autoimmune Diseases / Q000503:physiopathology*; D001835:Body Weight; D003404:Creatinine / Q000097:blood; D004326:Drinking; D004435:Eating; D005518:Food Preferences / Q000502:physiology*; D015850:Interleukin-6 / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D019463:Mice, Inbred MRL lpr; D012996:Solutions; D013395:Sucrose; D014162:Transfection
D015850:Interleukin-6; D012996:Solutions; D013395:Sucrose; D003404:Creatinine