Effect of cysteamine on the lysosomal enzymes of the hyperprolactinaemic rat pituitary.
The effect of cysteamine on the activity of lysosomal enzymes and the prolactin content of isolated hyperprolactinaemic cells has been investigated. In broken cell preparations, cysteamine markedly stimulated acid prolactin protease activity. In intact cells, however, cysteamine inhibited acid prolactin protease activity and beta-galactosidase. Moreover, the activities of alpha-mannosidase, acid phosphatase, beta-glucuronidase, total arylsulphatase and hexosaminidase were not changed by the addition of cysteamine. Cysteamine significantly depleted the cells of prolactin, and this action was not compromized by the inclusion of either leupeptin, chloroquine or NH4Cl in the incubation media. Taken together, these results indicate that cysteamine does not promote degradation of prolactin and hence depletion of prolactin from the pituitary through a mechanism involving lysosomal enzyme degradation.
Jeitner
T M
TM
Department of Physiology, Flinders Medical Centre, Bedford Park, South Australia.
Oliver
J R
JR
D000818:Animals; D003538:Cystamine / Q000494:pharmacology; D003543:Cysteamine / Q000494:pharmacology*; D006966:Hyperprolactinemia / Q000201:enzymology*; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D001616:beta-Galactosidase / Q000378:metabolism
D003543:Cysteamine; D011388:Prolactin; D001616:beta-Galactosidase; D003538:Cystamine