Age-dependent changes in rat lacrimal gland anti-oxidant and vesicular related protein expression profiles.
OBJECTIVE
Anti-oxidation and exocytosis are important for maintaining exocrine tissue homeostasis. During aging, functional and structural alterations occur in the lacrimal gland (LG), including oxidative damage to proteins, lipids, and DNA. The aims of the present study were to determine in the aging LG: a) the effects of aging on LG structure and secretory activity and b) changes in the expression of oxidative stress markers.


METHODS
To address these goals, tear secretion composition and corneal impression cytology were compared between male Wistar rats of 2 (control) and 24 (aged) months. LG morphology and the expression levels of vitamin E and malonaldehyde (MDA) were evaluated to determine the anti-oxidant activity and lipid peroxidation, respectively. RT-PCR and western blot analysis were used for the analysis of Ras related in brain GTPase protein (Rab) and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins of the secretory machinery (i.e.; Rab 3d, Rab 27, vesicle-associated membrane protein-2 (Vamp-2), and syntaxin).


RESULTS
Histological analysis of aged rats revealed a higher frequency of corneal epithelia metaplasia. In the acinar cells, organelles underwent degeneration, and lipofucsin-like material accumulated in the cytoplasm along with declines in the anti-oxidant marker vitamin E. Rab3d and Rab27b mRNA levels fell along with Rab3d protein expression, whereas syntaxin levels increased.


CONCLUSIONS
These findings indicate that exocytotic and anti-oxidant mechanisms become impaired with age in the rat LG. In parallel with these structural alterations, functional declines may contribute to the pathophysiology caused by tear film modification in dry eye disease.
Department of Physiology, Institute of Biology, Unicamp, Campinas, Brazil.
Thiago Martins
TM
Batista
Lilian Midori
LM
Tomiyoshi
Ana Carolina
AC
Dias
Letícia Prates
LP
Roma
Carolina Maria
CM
Módulo
Leonardo Tannus
LT
Malki
Elísio Bueno Machado
EB
Filho
Rafael
R
Deminice
Alceu Afonso
AA
Jordão
Daniel A
DA
Cunha
Eduardo Melani
EM
Rocha
D000375:Aging / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D003315:Cornea / Q000166:cytology / Q000378:metabolism; D019573:Epithelium, Corneal / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression; D007765:Lacrimal Apparatus / Q000166:cytology / Q000378:metabolism*; D015227:Lipid Peroxidation; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D013666:Tears / Q000378:metabolism; D050988:Vesicle-Associated Membrane Protein 2 / Q000235:genetics / Q000378:metabolism; D014810:Vitamin E / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020692:rab3 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D050765:Qa-SNARE Proteins; D050600:SNARE Proteins; C494706:Vamp2 protein, rat; D050988:Vesicle-Associated Membrane Protein 2; D014810:Vitamin E; D008315:Malondialdehyde; C512956:Rab27b protein, rat; C492133:Rab3d protein, rat; D020691:rab GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins