Cocaine- and amphetamine-regulated transcript (CART) is recently discovered peptide that has been involved in the control of appetite in mammals. The majority of peptides have been found in the brain, but CART was also demonstrated in gut and some endocrine glands like pituitary, pancreas and adrenals. In the present study we examined the effects of CART, using CART (55-102), on the structure and function of the thyroid gland. Single administration of CART caused dose dependent decrease of T4. In prolonged experiment we observed inhibition of pituitary-thyroid axis on the level of pituitary (rTSH concentration decrease), as well as, on the thyroid level (T4 and T3 concentration decrease). Stereometric analysis shows dose dependent decrease in epithelium volume associated with decrease in colloid volume. Our results suggest important role of CART in regulation of pituitary-thyroid axis function and thyroid gland structure.

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