Palatable food induces an appetitive behaviour in satiated rats which can be inhibited by chronic stress

Effects of Long-Term Acetyl-L-Carnitine Administration in Rats—II: Protection Against the Disrupting Effect of Stress on the Acquisition of Appetitive Behavior

“…The experimental procedure was previously described in detail (Ghiglieri et al, 1997). The day before the first training session, rats were allowed a first run in the Y-maze with one of the two arms closed.…”

“…However, no apparent correlation exists between the stress-induced behavioral modifications and these neurochemical effects. In fact, rats that have acquired VAB and are then exposed to chronic stress develop an avoidance deficit while retaining VAB (Ghiglieri et al, 1997); moreover, they show a DA output in the NAcS similar to that of control rats, and higher than that of chronically stressed rats . Furthermore, long-term treatment with lithium induces an avoidance deficit and a significant decrease in DA output in the NAcS (Gambarana et al, 1999b), but it does not interfere with VAB acquisition (Masi et al, 2000).…”

“…Chronic stress exposure not only induces an avoidance deficit, but it also disrupts the acquisition of an appetitive behavior sustained by a highly palatable food (vanilla sugar, VS; sustained appetitive behavior, VAB) in rats fed ad libitum (Ghiglieri et al, 1997). Moreover, it decreases DA and 5-HT output in the medial prefrontal cortex (mPFC) and NAcS (Gambarana et al, 1999a;Mangiavacchi et al, 2001).…”

“…Thus, no correlation can be demonstrated between basal DA output and VAB acquisition, as both long-term stress exposure and lithium treatment significantly reduce basal DA output in mesolimbic areas (Gambarana et al, 1999a, b;Mangiavacchi et al, 2001), but only lithium-treated rats maintain the competence to acquire VAB (Masi et al, 2000). However, satiated rats fed a palatable food show an increased DA release in the NAcS (Martel and Fantino, 1996;Ghiglieri et al, 1997) and in the mPFC, although rapid habituation to this effect selectively develops in the NAcS Di Chiara, 1997, 1999a). Thus, we hypothesized that the acute dopaminergic response to VS consumption in the NAcS and/or mPFC could be predictive of the capacity of satiated rats to learn VAB, and ALCAR treatment seemed to be a useful tool for testing this hypothesis.…”

Selective modifications in the nucleus accumbens of dopamine synaptic transmission in rats exposed to chronic stress

“…Longterm exposure to different unavoidable stress protocols decreases DA output in the nucleus accumbens shell (NAcS) and in the mPFC (Di Chiara and Tanda 1997;Gambarana et al 1999b;Mangiavacchi et al 2001), and it impairs responsiveness to both aversive and pleasurable stimuli (Overmier and Seligman 1967;Papp et al 1991;Moreau et al 1992;Gambarana et al 1995;Ghiglieri et al 1997). The impaired responsiveness to environmental stimuli induced by exposure to chronic stress has been used to model two depressive symptoms, hyporeactivity and anhedonia, or lack of motivation, as stressed rats do not show an avoidance response when exposed to avoidable noxious stimuli ) and they do not acquire an appetitive behavior (Ghiglieri et al 1997) or a palatable food-induced place preference (Papp et al 1991). Moreover, the repeated administration of antidepressants, e.g.…”