Effect of Exogenous Thyroxine on the Postnatal Development of Serotonin-containing Neuron in Fetal Alcohol Effects in the Rat Raphe Nuclei

Chung, Yoon Young; Kim, Ju Soo; Kim, Jong Joong

Abstract

Serotonin (5-hydroxytryptamine, 5-HT) has been concerned in the pathophysiology of various neuropsychiatric disorders. It is known to modulate emotion, cognition, endocrine activity, motor function, and pain. In the present study, the effects of exogenous thyroxine (T4) on the postnatal development of serotonin-containing neuron in the rat raphe nuclei with fetal alcohol effects were investigated using immunohistochemistry. These experimental animals were divided into three groups : the alcohol-fed group received 35 calories liquid ethanol diet; the control pair-fed group was fed a liquid diet in dextrin replaced alcohol isocalorically; alcohol+T4 group received alcohol diet and exogenous thyroxine subcutaneously. After the pups were born, the pups of each were fostered by surragate mother. An average of four pups, one from each litter, were killed at days 0, 7, 14, 21, and 28 for each of the above three groups. As a result, in alcohol group, serotonin-immunoreactivity was weakly stained at all postnatal ages compared to control pair-fed and alcohol+T4 group. The intensity of serotonin immunoreactivity was more prominent in alcohlol+T4 group than in control pair-fed group at P0. Mature patterns of serotonin-containing neurons were observed in control pair-fed and alcohol+T4 group at P7. A similar developmental pattern of serotonin-containing neuron was observed on and after P7 in control pair-fed and alcohol+T4 group. These results suggest that the increase of serotonin synthesis during early postnatal life caused by maternal administration of exogenous thyroxine may ameliorate fetal alcohol effects, one of the ill effects as a result of the dysthyroid state following maternal alcohol abuse.