Malnutrition during lactation in rats is associated with higher expression of leptin receptor in the pituitary of adult offspring

OBJECTIVE: Recent studies have shown that leptin receptor is expressed in human and rat pituitary glands. The expression of leptin receptor in rats whose dams were malnourished during lactation has not been previously reported. METHODS: We examined leptin receptor expression in the pituitary gland of adult rats whose dams were assigned to one of the following groups during lactation: control diet, protein-restricted diet (8% protein), or energy-restricted diet (the control diet fed in restricted quantities that were calculated according to the mean ingestion of the protein-restricted group). After weaning, all pups had free access to the control diet until they reached adult age, at which time leptin receptor expression in the pituitary was analyzed by immunohistochemistry. RESULTS: Adult animals from protein- and energy-restricted dams had a higher expression of leptin receptor in pituitary tissue, normal serum leptin concentrations, higher serum tri-iodothyronine concentrations, and lower thyroid-stimulating hormone concentrations than did the control rats. CONCLUSIONS: In the fed state, leptin lids a stimulatory effect on release of thyroid-stimulating hormone. The higher expression of leptin receptor in the pituitary. of animals from protein- and energy-restricted dams may suggest-a postreceptor failure in leptin action. This higher receptor expression may have allowed a greater inhibition of release of thyroid-stimulating hormone. (C)Elsevier Inc. 2004.