Endocrine Abstracts

Leptin is a hormone produced mainly from adipose tissue, which plays a major role in energy homeostasis. Its receptor Ob-R exists in five splice variants (Ob-Ra, b, c, d and e) with differing signal transduction abilities. The function of leptin and its receptor in development is not yet fully understood. This study determined the expression of leptin and its receptor in a number of fetal endocrine tissues.

Tissue samples were obtained from 7 fetal sheep at 130d (term 145±2d) after maternal administration of a lethal dose of barbiturate. Immunocytochemical analysis was carried out on adrenal, anterior pituitary and thyroid tissues. Sections were dewaxed and incubated overnight with a primary antibody raised against either leptin or its receptor (Ob-Rb). Specific binding was detected by a gold-labelled secondary antibody, amplified by silver enhancement.

Leptin and leptin receptor expression was detected in all three tissues examined but their respective localisation differed. Leptin and its receptor co-localised in all zones of the adrenal cortex. Receptor, but not leptin, expression was also found in the adrenal medulla localised to the nuclei of specific cells. In the anterior pituitary, leptin was expressed in the cytoplasm of positive cells. Leptin receptor was localised to the nuclei of cells with expression more widespread than leptin. Leptin was found in the follicular cells of the thyroid with receptor expression localised to the nuclei of these cells. These results indicate leptin receptor localisation to cell nuclei in the tissues examined. The functional significance of this nuclear localisation remains unclear at present.

Supported by the BBSRC.