Sex differences in heart rate variability measures that predict alcohol drinking in rats

Area of Science:

• Neuroscience
• Physiology
• Pharmacology

Background:

• Problem alcohol drinking is a significant public health burden, with increasing consumption and alcohol-related issues in women.
• Heart rate (HR) and heart rate variability (HRV) are potential biomarkers and drivers of pathological states, reflecting autonomic nervous system (ANS) balance.
• Sex differences in ANS regulation, with potential parasympathetic (PNS) predominance in women and sympathetic (SNS) predominance in men, may underlie differential risk factors for problem drinking.

Purpose of the Study:

• To investigate sex-specific associations between HRV measures and alcohol consumption levels in Wistar rats.
• To examine HRV and HR responses during alcohol-only consumption versus compulsion-like conditions (alcohol + quinine).
• To elucidate potential sex differences in autonomic mechanisms driving alcohol intake and aversion-resistant drinking.

Main Methods:

• Adult male and female Wistar rats were used to assess correlations between time-domain HRV measures (SDNN, rMSSD) and alcohol consumption.
• HRV and HR were measured at baseline, during drinking onset, and for 10 minutes post-consumption.
• Comparisons were made between alcohol-only and compulsion-like (alcohol + quinine) conditions to model aversion-resistant intake.

Main Results:

• Higher baseline and drinking onset PNS indicators in females correlated with greater alcohol consumption.
• Increased SNS indicators at drinking onset in males related to their alcohol intake levels.
• HR predicted alcohol intake in females post-consumption, while HRV changes during compulsion-like intake differed significantly between sexes, indicating aversion-resistant drinking mechanisms.

Conclusions:

• Novel sex-specific autonomic differences are associated with alcohol drinking behaviors.
• Parasympathetic and sympathetic nervous system activity may differentially influence alcohol consumption patterns in females and males.
• These findings suggest distinct autonomic mechanisms contributing to problem drinking, with potential clinical relevance for sex-specific therapeutic strategies.