Prenatal Ethanol Exposure Selectively Reduces the mRNA Encoding α-1 Thyroid Hormone Receptor in Fetal Rat Brain

Thyroid Function in Pregnant Women With Moderate to Severe Alcohol Consumption Is Related to Infant Developmental Outcomes

INTRODUCTION

Fetal alcohol spectrum disorders (FASD) have an estimated global prevalence of 2-5% of births, but prevalence is reported to be as high as 15.5% for FASD in certain high-risk communities in South Africa. Preclinical studies demonstrate that alcohol consumption during pregnancy interferes with thyroid hormone availability and function and negatively impacts exposed offspring. Very little is currently reported on this phenomenon in humans.

METHODS

This pilot study was embedded in the Drakenstein Child Health Study, a multi-disciplinary longitudinal birth cohort study investigating the early biological and psychosocial determinants of child health in South Africa. Twenty one mothers and their children with moderate-severe prenatal alcohol exposure (PAE) and 19 mothers and their children with no alcohol exposure were investigated. Maternal exposure history and blood samples were collected in mid-pregnancy and analyzed for serum-free thyroxin (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH). Children were assessed with formally measured growth parameters and development was evaluated using the Bayley III Scales of Infant and Toddler Development (BSID III) at 6 and 24 months of age.

RESULTS

While there were no significant differences in serum TSH and FT4 between groups, FT3 levels were significantly higher in mothers with moderate-severe prenatal alcohol use. In abstinent pregnant women, levels of FT4 were significantly correlated with infants' scores on cognitive measures at 6 and 24 months of age and with levels of gross motor skills at 24 months. However, in mothers with alcohol use, FT4 levels were not correlated with any cognitive or motor skills, but FT3 levels were significantly associated with scores on children's social-emotional development at 24 months of age.

DISCUSSION

Thyroid function in PAE is sufficiently disrupted to lead to alterations in serum FT3 levels. The contrast in findings between PAE and abstinent dyads in their association of maternal thyroid function and infant development further suggests that such disruption is present and may contribute to adverse neurodevelopment. Further work is needed to determine the relationship between peripheral thyroid indices during pregnancy and neurodevelopmental outcomes in the context of PAE.

The role of acetaldehyde in mediating effects of alcohol on expression of endogenous opioid system genes in a neuroblastoma cell line

Ethanol (EtOH) alters neural activity through interaction with various neurotransmitters and neuromodulators. The endogenous opioid system seems to play a key role in the activities of EtOH, since the opioid antagonist naltrexone (ReVia) attenuates craving. We have investigated the transcriptional regulation of opioid system genes in response to EtOH exposure for up to 96 h in human neuroblastoma SH-SY5Y cells using quantitative real-time polymerase chain reaction. We observed a significant decrease in the expression of opioid peptide precursors (proopiomelanocortin, proenkephalin, and prodynorphin) and of the kappa opioid receptor after 48 and 72 h of EtOH exposure (10 and 40 mM). These alterations were not present when the EtOH metabolism was blocked by 4-methylpyrazole. To evaluate whether the effects evoked by EtOH were possibly due to the first product of EtOH metabolism, cells were exposed to 0.4 mM acetaldehyde. We observed the same pattern of changes for prodynorphin, proenkephalin, and the kappa opioid receptor as after 72 h exposure to EtOH. These results contribute to our understanding of EtOH action at a cellular level and provide evidence of the role of acetaldehyde in mediating some of the EtOH-induced effects.

Prenatal programming of adult thyroid function by alcohol and thyroid hormones

Increasing evidence associates environmental challenges early in life with permanent alterations of physiological functions in adulthood. These changes in fetal environment can trigger physiological adaptations by the fetus, called fetal programming, which may be beneficial before birth but permanently influence the physiology of the organism. In this study, we investigated the potential connection between alcohol-induced decreased maternal thyroid function and the hypothalamic-pituitary-thyroid (HPT) function of adult rat offspring. Plasma 3,5,3'-triiodothyronine (T(3)), thyroxine (T(4)), and thyroid-stimulating hormone (TSH) levels were decreased in alcohol-consuming (E) dams on gestational day 21 compared with ad libitum- (C) and pair-fed (PF) controls. No significant differences were found in HPT function in young offspring (3 wk of age) between diet groups. However, adult fetal alcohol-exposed (FAE) offspring had significantly decreased levels of T(3) along with elevated TSH compared with control offspring. T(4) administration to the mother did not normalize the hypothyroid state of the adult FAE offspring. Interestingly, administration of T(4) to control pregnant dams decreased plasma T(3) of the adult female offspring only, whereas T(4) together with maternal alcohol consumption or pair-feeding led to decreased TSH and T(4) in the adult female offspring. Our results suggest that ethanol consumption and T(4) administration alter maternal HPT function, leading to prenatally programmed permanent alterations in the thyroid function of the adult offspring.