LEPTIN RECEPTOR MESSENGER-RNA IS EXPRESSED IN EWE ANTERIOR-PITUITARY AND ADIPOSE TISSUES AND IS DIFFERENTIALLY EXPRESSED IN HYPOTHALAMIC REGIONS OF WELL-FED AND FEED-RESTRICTED EWES

Infertility associated with suboptimal nutrition is a major concern am ong livestock producers. Recently, much effort has been put into under standing the role of the protein leptin in regulating feed intake and reproduction. Leptin, produced by adipocytes, has receptors in the hyp othalamus, but more precise locations of leptin receptor-expressing ce ll bodies have not been reported in a livestock species. The leptin re ceptor transcript has several splice variants in the mouse and human, but only the ''long-form'' product (OBRL) is capable of signal transdu ction. A partial ovine long-form leptin receptor cDNA was cloned and u sed to evaluate OBRL mRNA expression within hypothalamic, anterior pit uitary, and adipose tissues of ovariectomized adult ewes. Expression w as detected in reverse transcription-polymerase chain reaction product s of all tissues examined. OBRL, mRNA was detected by in situ hybridiz ation in the ventromedial and arcuate nuclei of the hypothalamus. In e wes that had been feed restricted for 3 wk before tissue collection, t he expression of OBRL mRNA in these areas was greater (P<0.05) than th at found in well-fed ewes. These findings provide evidence that the fu ll-length leptin receptor is expressed in hypothalamic, anterior pitui tary, and adipose tissue (the latter proffering an autoregulatory mech anism for leptin) and that within the hypothalamus, this receptor form is differentially expressed in well-fed vs. feed-restricted animals. (C) 1997 Elsevier Science Inc. 1997.