Perinatal ethanol exposure alters respiratory chemoreflex responses in anesthetized rats

Abstract

In the USA 10-15% of pregnant women drink alcohol (ethanol) leading to a variable compilation of developmental abnormalities, including deficits in critical homeostatic functions such as poor coordination of suckling, breathing, and swallowing. Here, we test the hypothesis that perinatal ethanol exposure alters respiratory chemoreflex responses in neonatal rats. Pregnant rats were exposed to 5% ethanol through their drinking water starting on embryonic day 5, which exposes the fetuses to ethanol during gestation and then after birth through the breast milk. Pups of both sexes were studied in the first week of life (postnatal days (P) 1-5). First, in awake pups, we used head-out plethysmography to assess the effects of ethanol exposure on the respiratory response to a brief, 5- minute episode of hypoxic hypercapnia (12% O2/5% CO2, balance N2, delivered through a nose cone). We found no significant differences in the frequency (P = 0.6667), tidal volume (P = 0.3627), or minute ventilation (P = 0.1582) responses to the challenge between control and ethanol exposed pups (2-way ANOVA, n = 6 control and 6 ethanol pups). In a second experiment, we used electromyography in anesthetized pups to study the diaphragm and tongue muscle responses to nasal occlusion, which results in strong muscle efforts but an absence of lung inflation, as well as hypoxia, hypercapnia, and acidosis. Here, we found that both diaphragm and tongue muscle EMG responses were significantly blunted in ethanol exposed animals compared to control. This included a decrease in the peak amplitude responses of both muscles (2-way ANOVA: diaphragm, P = 0.0175; tongue, P= 0.0317, n = 8 control and 8 ethanol pups), as well as a delay in the onset of the tongue muscle activation (Student’s unpaired T-test, P = 0.0219, n = 8 control and 8 ethanol pups). Together, these data indicate that perinatal ethanol exposure causes impairments in respiratory chemoreflex control, which appear to be highly dependent on level of arousal. NIH 5R01HD071302-08 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.