bq-123 and pepstatin

This study investigated the pruritogenic potency of cathepsin E, an aspartic protease, and its mechanisms in mice. An intradermal injection of cathepsin E to the rostral back elicited scratching, an itch-associated response, of the injection site. This action was inhibited by the aspartic protease inhibitor pepstatin A, the endothelin ET(A) receptor antagonist BQ-123, and the opioid receptor antagonists naltrexone and naloxone, but not by the H(1) histamine receptor antagonist terfenadine, the proteinase-activated receptor-2 antagonist FSLLRY-NH(2), or mast cell deficiency. Pepstatin A inhibited scratching induced by intradermal injection of the mast-cell degranulator compound 48/80, but not by tryptase, a mast-cell mediator. An intradermal injection of cathepsin E increased endothelin-1 levels in the skin at the injection site. Preproendothelin-1 mRNA was present in primary cultures of keratinocytes, and immunohistochemistry using an antibody recognizing endothelin-1 and big-endothelin-1 revealed immunoreactivity in the epidermis, especially in the prickle and granular cell layers, but not in the basal cell layer. These results suggest that cathepsin E is an endogenous itch inducer, and that its action is mediated at least in part by the production of endothelin-1 in the epidermis.

Topics: Animals; Behavior, Animal; Cathepsin E; Cells, Cultured; Endothelin Receptor Antagonists; Endothelin-1; Histamine Release; Keratinocytes; Male; Mice; Mice, Inbred ICR; Naloxone; Naltrexone; Narcotic Antagonists; Pepstatins; Peptides, Cyclic; Protease Inhibitors; Pruritus; Receptor, PAR-2; RNA, Messenger; Skin

To examine whether angiotensin II and endothelins produced in vascular smooth muscle cells can play roles in the regulation of mitogen-activated protein (MAP) kinase activity in vascular smooth muscle cells, we measured the activity of MAP kinases in cultured vascular smooth muscle cells, and determined effects of renin-angiotensin and endothelin systems activators and inhibitors. Angiotensin II and endothelin-1 produced an activation of MAP kinase activity in vascular smooth muscle cells, whereas the angiotensin receptor antagonist, losartan and the endothelin receptor antagonist, cyclo (D-alpha-aspartyl-L-prolyl-D-valyl-L-leucyl-D-tryptophyl, BQ123) inhibited the enzyme activity. MAP kinase activity in vascular smooth muscle cells was also inhibited either by the renin inhibitor pepstatin A or by the angiotensin-converting enzyme inhibitor captopril. The degree of the inhibition of MAP kinase activity by pepstatin A, captopril and losartan was almost the same. Renin produced a considerable increase in MAP kinase activity and the renin-induced MAP kinase activation was inhibited by pepstatin A. The endothelin precursor big endothelin-1 produced an increase of MAP kinase activity in vascular smooth muscle cells, whereas the endothelin-converting enzyme inhibitor phosphoramidon inhibited the enzyme activity. These findings suggest that functional renin-angiotensin system and endothelin system are present in vascular smooth muscle cells and these systems tonically serve to increase MAP kinase activity. It appears that renin or renin-like substances play the determining role in the regulation of renin-angiotensin system in vascular smooth muscle cells.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Captopril; Cells, Cultured; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Glycopeptides; Losartan; Male; Mitogen-Activated Protein Kinases; Muscle, Smooth, Vascular; Pepstatins; Peptides, Cyclic; Protease Inhibitors; Protein Precursors; Rats; Rats, Wistar; Renin