Endothelin protein expression in tear glands of the rabbit.
OBJECTIVE
Endothelin-1 (ET-1) has been found to accelerate rabbit corneal epithelial wound healing in vivo and proliferation of rabbit and bovine epithelial cells in vitro. We have now determined that endothelin-like immunoreactivity (ET-LI) is present in the tear fluid of New Zealand white rabbits, and we have addressed the question of whether it is produced by the tear glands (lacrimal gland and Harderian gland).


METHODS
Tears were obtained with capillary pipettes and lacrimal gland fluid was collected by cannulation. ET-LI was determined with a sandwich-enzyme immunoassay. The reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to determine if there are gene transcripts for prepro ET-1 in tear glands. ET-LI in the tear glands was evaluated using immunohistochemistry.


RESULTS
The tears contained 13.85 +/- 3.94 pg/ml (mean +/- SEM, n = 6) ET-LI and the lacrimal gland fluid had 24.90 +/- 6.00 pg/ml (n = 6). The plasma contained 0.89 +/- 0.20 pg/ml (n = 6). Gene transcripts were identified for prepro ET-1 in the lacrimal and Harderian glands. Specific staining for ET-LI was found in the epithelial cells of the ducts of the lacrimal gland and the acinar cells of the Harderian gland.


CONCLUSIONS
The higher concentrations of ET-LI in the tears and the lacrimal gland fluid than in plasma along with prepro ET-1 gene transcripts in the tear glands suggest that they secrete ET-1.
Takashima
Y
Y
Department of Ophthalmology and Visual Science, Kyoto University Graduate School of Medicine, Kyoto 606, Japan.
Takagi
H
H
Takahashi
M
M
Reinach
P S
PS
Mircheff
A K
AK
Warren
D W
DW
Yoshimura
N
N
D000818:Animals; D001483:Base Sequence; D002417:Cattle; D017931:DNA Primers / Q000235:genetics; D019332:Endothelin-1; D016232:Endothelins / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D006243:Harderian Gland / Q000378:metabolism; D007150:Immunohistochemistry; D007765:Lacrimal Apparatus / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D013666:Tears / Q000378:metabolism
D017931:DNA Primers; D019332:Endothelin-1; D016232:Endothelins; D011498:Protein Precursors; D012333:RNA, Messenger