Effects of dietary nucleotides on acute stress response and cannabinoid receptor 1 mRNAs in sole, Solea solea

The objective of the present study was to evaluate the modulation of acute stress response by dietary nucleotides (NT) in sole, Solea solea. A basal diet was supplemented with levels of 0 (normal diet), or 0.4 g NT/kg dry diet for 8 weeks. At the end of feeding trial, fish fed the normal and NT-supplemented diet were subjected to a standardized protocol of disturbance and sampled over a 24 h recovery after the stressor exposure. Modulatory effects of NT on acute stress response (cortisol and glucose), proopiomelanocortin (POMC) and cannabinoid receptor 1 splice variants (CB1A and CB1B) mRNA levels were studied. Both plasma cortisol and glucose levels of fish fed NT-supplemented diet were significantly lower than fish fed the control diet at 1 and 4 h post-stress time-points. There are no significant effects of dietary NT on POMC and HSP70 mRNA levels. In our study, both CB1A and CB1B trascript levels were induced in fish fed the normal diet at 1 and 4 h post-stress intervals. Collectively, the results obtained suggest that dietary NT modulates the CB1-like receptor mRNA expressions leading to attenuation in stressor-induced plasma cortisol level in sole.