Highly palatable food normalizes the HPA axis activity and modulates anxiety‐like behaviors in rats that experienced neonatal maternal separation

In this study, we have examined the effect of highly palatable food (HPF) on the psycho‐emotional behaviors of rats that experienced neonatal maternal separation. Male SD pups were separated from dam for 3 h daily during PND 2–14 (MS) or left undisturbed (NH). Half of NH and MS pups had free choices of cookie (HPF) and chow from PND 28, the rest half chow only, and were subjected to behavioral tests during young adulthood. Plasma corticosterone levels were analyzed by radioimmunoassay, and tissue contents of ΔFosB and pCREB in the nucleus accumbens by western blot. Caudal grooming was reduced in MS‐control and NH‐HPF compared with NH‐control. HPF suppressed defecation activity in MS, but not in NH. HPF increased anxiety‐like behaviors during elevated plus maze test and depression‐like behaviors during swim test in NH, and these behaviors were not further affected by HPF in MS. Stress‐induced corticosterone increase was blunted by MS experience, and HPF appeared to normalize it. pCREB in the nucleus accumbens was increased, and ΔFosB decreased, by MS experience, and HPF normalized them. Results demonstrate that long‐term HPF may normalize the HPA axis activity and modulate anxiety‐like behaviors in MS rats, likely in relation with neural plasticity in the nucleus accumbens. Supported by the 21st Century Frontier Research Program (2009K001269) and the NRF (2010‐0003642) funded by MOEST