Gene expression of lipoxygenases and leukotriene receptors along the rat nephron. The arachidonate signalling pathways comprise prostanoids formed by cyclooxygenases, EETs and HETEs formed by CYP450 enzymes and HETEs and leukotrienes generated by lipoxygenases. Whilst the intrarenal localization of cyclooxygenases and of some CYP450 enzymes along the nephron has already been determined, the localization of lipoxygenases and leukotriene forming enzymes together with leukotriene receptors in the kidney is less clear. This study therefore aimed to determine the expression of 5-, 12- and 15-lipoxygenases as well as the leukotriene receptors along the rat nephron. The kidneys were dissected in cortex, outer and inner medulla and the microdissected nephron segments were collected after a collagenase digestion. mRNA abundance was determined by RT-PCR and real time PCR. 15-LOX mRNA showed a characteristic expression pattern along the distal nephron. 12-LOX mRNA was only found in the glomerulus. Similarly 5-LOX mRNAs together with the 5-LOX activating protein mRNAs were expressed in the glomerulus and in addition in the vasa recta. The leukotriene A4 hydrolase was found in all nephron segments, whilst leukotriene C4 synthase mRNA could not be found in any nephron segment. The leukotriene receptor B4 and the cysteinyl leukotriene receptor type 1 were selectively expressed in the glomerulus, while cysteinyl receptor type 2 was not found in any nephron segment. Our data suggest that the glomerulus is a major source and target for 5- and 12-HETE and for leukotrienes. The collecting duct system on the other hand appears to be a major source of 15-HETE.