title: Extra-pancreatic insulin production in RAt lachrymal gland after streptozotocin-induced islet beta-cells destruction.
abstract: Previous work has revealed that insulin is secreted in the tear film; its mRNA is expressed in the lachrymal gland (LG) and its receptor in tissues of the ocular surface. To test the hypothesis of insulin production in the LG, we compared normal and diabetic rats for: (1) the presence of insulin and C-peptide, (2) glucose- and carbachol-induced insulin secretion ex-vivo, and (3) biochemical and histological characteristics of diabetic LG that would support this possibility. Four weeks after streptozotocin injection, blood and tears were collected from streptozotocin-diabetic male Wistar rats. Insulin levels in the tear film rose after glucose stimulation in diabetic rats, but remained unchanged in the blood. Ex vivo static secretion assays demonstrated that higher glucose and 200 microM carbachol significantly increased mean insulin levels from LG samples of both groups. Insulin and C-peptide were expressed in LG of diabetic rats as determined by RIA. Comparable synaptophysin immune staining and peroxidase activity in the LG of both groups suggest that the structure and function of these tissues were maintained. These findings provide evidence of insulin production by LG. Higher expression of reactive oxygen species scavengers may prevent oxidative damage to LG compared to pancreatic beta-cells.
authors.affiliation: Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Daniel Andrade
authors.initials: DA
authors.lastname: Cunha
authors.forename: Mônica C
authors.initials: MC
authors.lastname: de Alves
authors.forename: Luiz Fabrizio
authors.initials: LF
authors.lastname: Stoppiglia
authors.forename: Angélica Gobbi
authors.initials: AG
authors.lastname: Jorge
authors.forename: Carolina Maria
authors.initials: CM
authors.lastname: Módulo
authors.forename: Everardo M
authors.initials: EM
authors.lastname: Carneiro
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Boschero
authors.forename: Mário J A
authors.initials: MJ
authors.lastname: Saad
authors.forename: Lício A
authors.initials: LA
authors.lastname: Velloso
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Rocha
mesh_terms: D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000494:pharmacology; D007150:Immunohistochemistry; D007328:Insulin / Q000096:biosynthesis* / Q000097:blood; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007765:Lacrimal Apparatus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin / Q000633:toxicity; D016708:Synaptophysin / Q000378:metabolism
chemical_list: D007328:Insulin; D016708:Synaptophysin; D013311:Streptozocin; D002217:Carbachol; D009195:Peroxidase; D005947:Glucose