Intermittent access to sucrose increases sucrose-licking activity and attenuates restraint stress-induced activation of the lateral septum

摘要

Intermittent access to palatable food can attenuate anorectic and hormonal responses to stress in rats. The neuronal mechanisms of modulation of stress response by diets are not fully understood. The present study was conducted to create rat models with intermittent access to sucrose that demonstrate resistance to stress-induced hypophagia, to study the pattern of sucrose consumption by these rat models, and to investigate in which brain structures intermittent sucrose regimens modify stressinduced neuronal activation. The obtained results demonstrate that 6-wk intermittent access to sucrose without food restriction (4 day/wk ad libitum access to sucrose in addition to chow, and following 3 day/wk exclusive feeding of chow; SIA rats) and combined with food restriction (4 day/wk access to chow and sucrose restricted to 2 h/day, and following 3 days/wk on unrestricted chow; SIR rats) increased sucrose-licking activity. The alterations in the rats' feeding behavior were accompanied by a resistance of their body weight gain and food intake to 1-h restraint stress applied once per week. The chronic intermittent sucrose consumption significantly lowered, in the SIA and SIR rats, the levels of expression of corticotropin-releasing factor type 2 receptor and restraint stress-induced expression of c-fos mRNA in the medioventral part of the lateral septum. Conversely, the levels of the corticotropin-releasing factor type 2 receptor transcript in the ventromedial hypothalamic nucleus were decreased only in the foodrestricted SIR rats. The lower stress-induced neuronal activation in the medioventral part of the lateral septum may contribute to the attenuated anorectic stress response in the rats maintained on intermittent sucrose regimens.