Tactile stimulation during different developmental periods modifies hippocampal BDNF and GR, affecting memory and
Caren T D Antoniazzi1, Vinícia G Metz2, Karine Roversi1
1Programa de Pós-graduação em Farmacologia Universidade Federal de Santa Maria, RS, Brazil.
Insights
Tactile stimulation (TS) during postnatal days 8-14 in rat pups significantly reduces anxiety and improves stress coping in adulthood. This specific developmental window optimizes the long-term benefits of early-life touch.
Area of Science:
- Neuroscience
- Developmental Psychology
- Behavioral Biology
Background:
- Early life experiences, including tactile stimulation (TS), can profoundly impact long-term neurodevelopment and behavior.
- Previous research indicates TS in pups can mitigate fear, anxiety, and addiction later in life.
- The precise timing of TS during preweaning development for optimal neurobiological effects remains unclear.
Purpose of the Study:
- To determine the specific preweaning period (postnatal days 1-7, 8-14, or 15-21) where TS exerts the greatest influence on neuronal development and adult behavior.
- To assess the impact of targeted TS periods on anxiety-like behaviors, working memory, stress response, and neurochemical profiles in adult rats.
Main Methods:
- Male rat pups were exposed to controlled tactile stimulation during distinct developmental windows: postnatal days (PND) 1-7, PND8-14, or PND15-21.
- Adult rats underwent comprehensive behavioral assessments, including the elevated plus maze, Y-maze, and defensive burying test.
- Biochemical and molecular analyses were performed on hippocampal tissue, measuring corticosterone levels, oxidative stress markers (lipid peroxidation, catalase activity), and neurotrophic factors (BDNF) and receptor expression (glucocorticoid receptors).
Main Results:
- TS during PND8-14 significantly reduced anxiety-like behaviors and improved working memory compared to other TS groups and controls.
- This critical PND8-14 window enhanced the ability to cope with stress, as evidenced by reduced burying behavior.
- TS during PND8-14 also led to lower corticosterone levels, improved oxidative status, increased hippocampal BDNF, and decreased glucocorticoid receptor expression.
- TS during the first week (PND1-7) was associated with increased anxiety-like behavior.
Conclusions:
- The period between postnatal days 8-14 is a critical window for tactile stimulation to confer lasting beneficial effects on emotionality and stress resilience in rats.
- Targeted TS during this specific neonatal phase can optimize neuronal development, leading to reduced anxiety and enhanced cognitive function in adulthood.
- These findings highlight the importance of the timing of early-life sensory experiences for long-term behavioral and neurobiological outcomes.
Abstract:
Recent studies have shown that tactile stimulation (TS) in pups is able to prevent and/or minimize fear, anxiety behaviors, and addiction to psychostimulant drugs in adult rats. In these studies, animals have been exposed to handling from postnatal day (PND) 1-21. This study was designed to precisely establish which period of preweaning development has a greater influence of TS on neuronal development. After birth, male pups were exposed to TS from PND1-7, PND8-14, and PND15-21. In adulthood, the different periods of postnatal TS were assessed through behavioral, biochemical, and molecular assessments. Animals that received TS from PND8-14 showed lower anxiety-like symptoms, as observed by decreased anxiety index in elevated plus maze. This same TS period was able to improve rats' working memory by increasing the percentage of alternation rate in Y-maze, and induce better ability to cope with stressful situations, as showed in the defensive burying test by a reduced time of burying behavior. On the other hand, animals receiving TS in the first week of life showed longest cumulative burying time, which is directly related to increased anxiety-like behavior. Moreover, TS from PND8-14 showed lower corticosterone levels and better oxidative status, as observed by decreased lipid peroxidation and increased catalase activity in the hippocampus. Brain-derived neurotrophic factor (BDNF) immunocontent was increased in the hippocampus of animals receiving TS from PND8-14, while glucocorticoid receptors immunocontent was decreased in both TS1-7 and TS15-21 , but not TS8-14 . To the best of our knowledge, this study is the first to show TS can be more efficient if applied over a focused period of neonatal development (PND8-14) and this beneficial influence can be reflected on reduced emotionality and increased ability to address stressful situations in adulthood. © 2016 Wiley Periodicals, Inc.
