Highly Palatable Food during Adolescence Improves Anxiety-Like Behaviors and Hypothalamic-Pituitary-Adrenal Axis
Jong-Ho Lee1, Jin Young Kim2, Jeong Won Jahng3
1Program in Craniofacial Structure and Functional Biology, Department of Dental Science, Graduate School, Seoul National University School of Dentistry, Seoul, Korea. ; Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul, Korea. ; Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea.
Insights
Highly palatable food consumption in adolescence partially mitigates anxiety behaviors in rats with early life stress. However, it did not improve depressive symptoms, suggesting a complex interaction with the hypothalamic-pituitary-adrenal axis.
Area of Science:
- Neuroscience
- Behavioral Science
- Endocrinology
Background:
- Neonatal maternal separation (MS) is a model for early life stress, leading to adverse behavioral outcomes.
- Adolescent highly palatable food (HPF) consumption may influence stress-related behaviors and neuroendocrine function.
Purpose of the Study:
- To investigate the impact of ad libitum HPF consumption during adolescence on behavioral and hormonal responses in rats subjected to neonatal maternal separation.
Main Methods:
- Male Sprague-Dawley rats underwent daily maternal separation (MS) or were nonhandled (NH).
- Half of MS rats received access to chocolate cookies (MS+HPF) from postnatal day 28.
- Behavioral tests and plasma corticosterone analysis were performed in young adulthood.
Main Results:
- MS rats exhibited increased anxiety-like behaviors (reduced open arm exploration, increased immobility) and blunted corticosterone response to stress.
- HPF consumption normalized ambulatory and defecation activities and grooming in MS rats.
- HPF did not improve anxiety-related behaviors in the elevated plus maze or swim tests, but normalized stress-induced corticosterone levels.
Conclusions:
- Adolescent HPF consumption partially ameliorates anxiety-related symptoms in rats with neonatal maternal separation.
- This improvement may be linked to the normalization of hypothalamic-pituitary-adrenal (HPA) axis function.
- HPF did not alleviate depressive-like symptoms in this model.
Background:
This study was conducted to examine the effects of ad libitum consumption of highly palatable food (HPF) during adolescence on the adverse behavioral outcome of neonatal maternal separation.
Methods:
Male Sprague-Dawley pups were separated from dam for 3 hours daily during the first 2 weeks of birth (maternal separation, MS) or left undisturbed (nonhandled, NH). Half of MS pups received free access to chocolate cookies in addition to ad libitum chow from postnatal day 28 (MS+HPF). Pups were subjected to behavioral tests during young adulthood. The plasma corticosterone response to stress challenge was analyzed by radioimmunoassay.
Results:
Daily caloric intake and body weight gain did not differ among the experimental groups. Ambulatory activities were decreased defecation activity and rostral grooming were increased in MS controls (fed with chow only) compared with NH rats. MS controls spent less time in open arms, and more time in closed arms during the elevated plus maze test, than NH rats. Immobility duration during the forced swim test was increased in MS controls compared with NH rats. Cookie access normalized the behavioral scores of ambulatory and defecation activities and grooming, but not the scores during the elevated plus maze and swim tests in MS rats. Stress-induced corticosterone increase was blunted in MS rats fed with chow only, and cookie access normalized it.
Conclusion:
Prolonged access to HPF during adolescence and youth partly improves anxiety-related, but not depressive, symptoms in rats that experienced neonatal maternal separation, possibly in relation with improved function of the hypothalamic-pituitary-adrenal (HPA) axis.
