Leptin serum concentration in early life is an important factor for adequate future development of the offspring. We demonstrated that hyperleptinaemia on lactation programmed for hyperleptinaemia, central leptin resistance with lower hypothalamus OBRb expression and higher medullary catecholamine levels with cardiovascular consequences at adulthood. The central objective of this study was to determine the direct effect of leptin on adrenal medullary function of adult rats that were leptin treated during lactation. Adrenal morphology was also accessed. Recombinant murine leptin was injected in the pups during the first 10 days of life (group L, leptin programmed) or at adulthood during 6 days (group LC). Controls of both experiments received saline (groups C and CC). Both treatments resulted in hyperleptinaemia at 150 days old (+78% and 2 fold increase, respectively; p<0.05). Programmed animals showed hypertrophy of adrenal and higher adrenal catecholamine content at 150 days old (3 fold increase, p<0.05), and no changes were observed in the LC group. However, LC rats had lower adrenal content of tyrosine hydroxylase (-17%, p<0.05). Leptin programmed rats had a lower response to leptin in vitro stimulation (-22%, p<0.05) and lower expression of key proteins of the leptin signalling pathway, OBR and JAK2 in the medullae (-61% and -29%, respectively, p<0.05). However, they presented higher expression of p-STAT3 (+2 fold, p<0.05). Leptin treatment at adulthood did not affect these parameters. The higher catecholamines synthesis and secretion in the leptin programmed rats observed in our previous study does not seem to be a consequence of the direct effect of leptin upon the medullae. We suggest that the hyperleptinaemia of the programmed animals increases adrenal medullary function through SNS activation. In conclusion, high leptin levels on lactation programs the activity of the sympathoadrenal system at adulthood that may contribute to the development of adult chronic diseases such as hypertension.
- leptin receptor
- adrenal medulla
- Copyright © 2009, American Journal of Physiology - Endocrinology and Metabolism