Effects of Chronic Prenatal Alcohol Exposure on Nociceptive Responses to Mechanical and Thermal Stimuli in Rats

The present study sought to investigate the effects of chronic prenatal alcohol exposure (PAE) on nociceptive responses to mechanical and thermal stimuli in rats. The Von Frey and Hot Plate tests were employed to assess the nociceptive responses of 10 control rats and 7 experimental rats whose mothers had been administered ethanol from day 5 to day 20 of gestation. In healthy animals, a decrease in pain sensitivity was observed between days 28 and 70, which was not observed in the experimental group. The findings also indicated that rats with PAE exhibited diminished sensitivity to nociceptive stimuli during the early postnatal period, as evidenced by a higher threshold response to mechanical stimuli at day 28 than in the control group. However, those observations did not apply to thermal stimuli. It appears that this may be a result of distinctiveness in neural pain pathways for particular stimuli at the receptor or ion channel level, while a disruption in the equilibrium between the sympathetic and parasympathetic nervous systems may be a contributing factor. The results of this study highlight a critical aspect of the harmful systemic effects of alcohol, while also underscoring the need for further research to elucidate the underlying mechanisms, including the role of the hypothalamic-pituitary-adrenal axis and the serotonergic system in modulating pain responses in individuals prenatally exposed to alcohol.