Ž . Brain Research 759 1997 269–278 Research report High levels of human chymase expression in the pineal and pituitary glands 1 Ovidiu Baltatu a,d , Hikaru Nishimura a , Sigrid Hoffmann a , Gisela Stoltenburg c , Ioan D. Haulica d , Andrea Lippoldt a , Detlev Ganten a,b , Hidenori Urata a,e, ) a ( ) Max-Delbruck-Center for Molecular Medicine MDC , D-13122, Berlin-Buch, Germany ¨ b Institute for Clinical Pharmacology, UniÕersity Clinic, Benjamin Franklin, Free UniÕersity, D-12200 Berlin, Germany c Institute for Neuropathology, UniÕersity Clinic, Benjamin Franklin, Free UniÕersity, D-12200 Berlin, Germany d UniÕersity of Medicine, Department of Physiology, R-6600 Iasi, Romania e Fukuoka UniÕersity, Department of Internal Medicine, Fukuoka 814-80, Japan Accepted 3 December 1996 Abstract The brain renin–angiotensin system plays a role in both cardiovascular homeostasis and neurosecretory functions. Since the Ž . mechanisms of angiotensin Ang II formation in the human brain have not been clarified, the aims of the present study were to determine Ž . the presence of human chymase and angiotensin I-converting enzyme ACE in human and non-human brains. In the human brain, the Ž total Ang II-forming activity was significantly higher in the pineal and pituitary glands than those in other regions. In other species rat, . bovine and porcine , the level of chymase as well as total Ang II-forming activities in pineal glands were significantly lower than those in Ž. human glands. High levels of chymase-like immunoreactivity ir were found in the arteriolar endothelial cells, adventitial mesenchymal cells and in parenchymal cells of the human pineal and pituitary glands while ACE-ir was mostly observed in the endothelial cells and occasionally found in parenchymal cells. Our study provides the first evidence that human chymase exists in the pineal and pituitary glands. The remarkable regional and species differences in mechanisms of Ang II formation suggest a specific role of chymase or ACE in the human brain. q 1997 Elsevier Science B.V. All rights reserved. Keywords: Brain renin–angiotensin system; Pineal; Angiotensin I-converting enzyme; Angiotensin II receptor; Immunocytochemistry 1. Introduction Ž . The tissue renin–angiotensin system RAS exerts au- tocrine and paracrine actions on local regulatory processes in various regions of the mammalian brain, probably in- w x volved in cardiovascular homeostasis 42 . In addition to ACE, other enzymes have been suggested to alternatively Ž w x. form Ang II in the brain reviewed in 30 . Recent in vitro studies on the human heart indicated the w x existence of dual pathways of Ang II formation 38 ; ACE Ž . formed a minor portion f 11% of total Ang II while the Ž . major component f 75–80% was due to a serine pro- ) Corresponding author. Max-Delbruck Center for Molecular Medicine ¨ Ž . MDC , Hypertension Research, Wiltbergstraße 50, 13122 Berlin-Buch, Ž . Germany. Fax: q49 30 9417-2510. 1 A portion of these studies has been presented in abstract form at the 49th Annual Fall Conference and Scientific Sessions of the Council for Ž . High Blood Pressure Research 1995. Hypertension 26:555 . teinase. This cardiac Ang II-forming serine proteinase was isolated, identified and characterized as a novel member of Ž . w x the chymase subfamily human heart chymase 39,40 . Mammalian chymases were originally identified in mast w x cells 32 and are postulated to be involved in neurogenic inflammation, submucosal gland secretion, parasite expul- sion, lipoprotein and extracellular matrix catabolism and in wx vasoactive peptide metabolism 7 . Although the structures of chymases in different species show extensive homology, their enzymatic properties differ markedly with respect to w x substrate specificity and catalytic efficiency 39,41 . Puri- fied human heart chymase is the most efficient and spe- w x cific Ang II-forming enzyme 39 . The biochemical charac- teristics of human chymase are distinctly different from other known Ang II-forming enzymes, including ACE, w x tonin, kallikrein and cathepsin G 39 . w x Chymase has been found in various human tissues 36 , although no previous study exists regarding the human brain. In the present study, we investigated whether chy- mase-like activity is present in the human brain. Human 0006-8993r97r$17.00 Copyright q 1997 Elsevier Science B.V. All rights reserved. Ž . PII S0006-8993 96 01474-6