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Neonatal handling prevents anxiety-like symptoms in rats exposed to chronic mild stress: behavioral and oxidative
Nardeli Boufleur1, Caren T D Antoniazzi, Camila S Pase
1Programa de pós Graduação em Farmacologia, Universidade Federal de Santa Maria, RS, Brazil.
Insights
Neonatal handling, particularly tactile stimulation (TS), protects adult rats from chronic mild stress (CMS) effects. This early life intervention mitigates stress-induced anxiety and biochemical changes, enhancing coping abilities.
Area of Science:
- Neuroscience
- Behavioral Biology
- Stress Research
Background:
- Neonatal handling influences adult stress responses.
- Chronic mild stress (CMS) induces behavioral and biochemical alterations.
Purpose of the Study:
- To investigate the impact of neonatal tactile stimulation (TS) and maternal separation (MS) on adult stress resilience.
- To assess the protective effects of early life handling against CMS-induced behavioral and biochemical changes.
Main Methods:
- Rat pups received daily TS or MS from PND1 to PND21.
- Adult rats were exposed to CMS for 3 weeks.
- Behavioral tests (sucrose preference, elevated plus maze, defensive burying) and biochemical assessments (vitamin C, oxidative stress markers) were performed.
Main Results:
- CMS reduced sucrose preference, increased anxiety, and elevated adrenal weight.
- CMS decreased plasma vitamin C and increased oxidative stress markers (protein carbonyl, catalase, superoxide dismutase).
- Neonatal handling (TS and MS) prevented most CMS-induced negative effects, with TS showing additional benefits in reducing anxiety and cortical oxidative stress.
Conclusions:
- Neonatal handling, especially TS, confers significant protection against chronic mild stress in adulthood.
- Early life interventions can enhance an organism's ability to cope with stressful situations later in life.
- TS may be a particularly effective method for promoting long-term stress resilience.
Abstract:
This study investigated the influence of neonatal handling on behavioral and biochemical consequences of chronic mild stress (CMS) in adulthood. Male rat pups were submitted to daily tactile stimulation (TS) or maternal separation (MS), from postnatal day 1 (PND1) to postnatal day 21 (PND21), for 10 min/day. In adulthood, half the number of animals were exposed to CMS for 3 weeks and submitted to behavioral testing, including sucrose preference (SP), elevated plus maze (EPM), and defensive burying tasks (DBTs), followed by biochemical assessments. CMS reduced SP, increased anxiety in EPM and DBT, and increased adrenal weight. In addition, CMS decreased plasma vitamin C (VIT C) levels and increased protein carbonyl (PC) levels, catalase (CAT) activity in hippocampus and cortex, and superoxide dismutase (SOD) levels in cortex. In contrast, both forms of neonatal handling were able to prevent reduction in SP, anxiety behavior in DBT, and CMS-induced adrenal weight increase. Furthermore, they were also able to prevent plasma VIT C reduction, hippocampal PC levels increase, CAT activity increase in hippocampus and cortex, and SOD levels increase in cortex following CMS. Only TS was able to prevent CMS-induced anxiety symptoms in EPM and PC levels in cortex. Taken together, these findings show the protective role of neonatal handling, especially TS, which may enhance ability to cope with stressful situations in adulthood.
