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Effect of a somatostatin analogue (SMS 201-995) on tear secretion in rats
Z Kapicioğlu1, I N Kalyoncu, O Deger
1Karadeniz Technical University, School of Medicine, Department of Ophthalmology, Pharmacology, Biochemistry and Public Health, Trabzon, Turkey.
Purpose:
In this study we investigated the effect of a somatostatin analogue, octreotide, (SMS 201-995) on tear secretion in rats.
Method:
The animals were anaesthetized intraperitoneally (ip) with urethan (1.2 g/kg) The drugs were injected subcutaneously (sc.). Tear samples were collected by folding a 5 mm section of the Schirmer strip over the lower lid margin to absorb tear fluid from the lower conjunctival sac for 5 mm. Forty animals were divided into four groups (n = 10). Group I (control) received 1 ml of saline, group 2 received 100 microg/kg of SMS 201-995, group 3 received 50 microg/kg of acetylcholine (Ach), group 4 received 100 microg/kg of SMS 201-995 and 30 min later 50 microg/kg of Ach. At t = 0 the local anesthetic proparacain HCI was instilled onto the ocular surface to minimize reflex secretion. Baseline secretion was measured before administering the various treatments.
Results:
While Ach alone significantly increased tear secretion, SMS 201-995 reduced it compared to saline (control) (p<0.0001, p<0.001, respectively). SMS 201-995 combined with Ach decreased tear secretion compared to Ach alone (p<0.03).
Conclusion:
SMS 201-995 significantly inhibits Ach stimulated tear secretion in rats.