Predictable chronic mild stress improves mood, hippocampal neurogenesis and memory

Area of Science:

• Neuroscience
• Behavioral Science

Background:

• Adult hippocampal neurogenesis is crucial for mood and memory.
• Unpredictable chronic stress (UCS) impairs neurogenesis and cognitive functions.
• The impact of predictable chronic mild stress (PCMS) on adult brain function remains unclear.

Purpose of the Study:

• To investigate the effects of PCMS on mood, memory, and hippocampal neurogenesis in adult rats.
• To determine if PCMS influences depressive- and anxiety-like behaviors.
• To assess the impact of PCMS on cognitive functions and neural plasticity.

Main Methods:

• Adult rats were exposed to daily 5-minute restraint stress for 28 days (PCMS).
• Behavioral tests included the Forced Swim Test (FST) and Elevated Plus Maze (EPM) for mood and anxiety.
• Memory function was assessed using the Water Maze Test (WMT) and Novel Object Recognition Test (NORT).
• Hippocampal neurogenesis was quantified by measuring the production and growth of new neurons.

Main Results:

• PCMS significantly reduced depressive- and anxiety-like behaviors for extended periods.
• A notable ~1.8-fold increase in hippocampal neurogenesis (new neuron production and growth) was observed after PCMS.
• PCMS administration led to enhanced memory performance in both WMT and NORT.
• These behavioral and cognitive improvements correlated with increased hippocampal neurogenesis.

Conclusions:

• Predictable chronic mild stress (PCMS) demonstrates beneficial effects on adult brain function.
• PCMS promotes hippocampal neurogenesis, leading to improved mood and cognitive capabilities.
• Routine, predictable stress may play a positive role in maintaining brain health and function, contrasting with unpredictable stress models.