| Abstract | Cilj istraživanja: Kako prolongirani učinak lokalnih anestetika na oko može imati štetne posljedica, pokušali smo dokazati da lokalno primijenjeni BPC 157 skraćuje anesteziju rožnice nakon topičke primjene lokalnih anestetika. Taj je učinak posredovan sustavom dušičnog oksida. Nacrt studije: Za istraživanje je provedena studija u obliku randomiziranog slijepog kontroliranog pokusa. Materijal i metode: Nakon intraperitonealne sedacije diazepamom, muškim Wistar štakorima smo Cochet-Bonnet esteziometrom mjerili osjetljivost rožnice nakon anesteziranja rožnice lokalnim anestetikom – 0,5% tetrakainom ili 0,4% oksibuprokainom, Nakon lokalnih anestetika, štakori su tretirani nekom od istraživanih tvari (BPC 157, L-arginin, L-NAME) ovisno u koju su grupu randomizirani. Cochet-Bonnet esteziometar sastoji se od najlonskog monofilamenta koji se može izvlačiti i koji proizvodi silu pritiska na svom vrhu. Ta je sila obrnuto proporcionalna duljini izvučenog dijela filamenta. Filament je promjera 0,12 mm i maksimalne duljine 6 cm. Mjerenje osjetljivosti rožnice započeli smo nježnim dodirom rožnice vrhom maksimalno izvučenog filamenta okomito na rožnicu i primjenom malog pritiska kojim nježno savijemo filament. Ako je štakor trepnuo, to smo zabilježili kao pozitivan odgovor. Ako ne bi trepnuo, nit bismo skratili za 1 cm i ponavljali testiranje dok ne dobijemo pozitivan odgovor. Odsutnost pozitivnog odgovora kada je nit izvučena na duljinu od 1 cm se definira kao kompletni kornealni blok. Bilježili smo duljinu niti koja bi izazvala pozitivan dogovor ili 0 u slučaju kompletnog bloka. Testiranje smo inicijalno izveli prije aplikacije lokalnih anestetika i kasnije u intervalima od 5 minuta do povratka početne osjetljivosti. Rezultati: I u tetrakainskoj i u podskupini anesteziranoj oksibuprokainom evidentno je skraćenje kompletne anestezije rožnice (T1) i vrijeme povratka početne osjetljivosti (T2) kod skupine tretirane BPC-jem 157. tetrakain T1: kontrola 59 ± 5,2 min, BPC 157 45 ± 4,6 min, p < 0,001 T2: kontrola 109 ± 12,5 min, BPC 157 94 ± 7,0 min, p = 0,008 oksibuprokain T1: kontrola 64 ± 5,7 min, BPC 157: 51 ± 5,0 min, p < 0,001 T2 kontrola: 126 ± 3,9 min, BPC 157: 106 ± 7,4 min, p < 0,001. Skraćenje anestezije pojavilo se i kod skupina tretiranih L-argininom, dok se kod skupina tretiranih L-NAMEom anestezija produljila. Zaključak: Djelovanjem putem sustava dušikovog oksida, BPC 157 uspješno je skratio trajanje anestezije rožnice štakora nakon topičke aplikacije lokalnih anestetika na nju. Temeljem provedenog istraživanja pokazali smo da se BPC 157 može koristiti kao antagonist učinku lokalnih anestetika na rožnici štakora. |
| Abstract (english) | Objectives: As prolonged effect of local anesthetics can be harmful to the eye, we tried to prove that locally applied BPC 157 shortens corneal anesthesia after topical application of local anesthetics and that this effect is nitric oxide mediated. Study design: Randomized blind controlled experiment was conducted. Material and methods: First, the male Wistar rats were intraperitoneally sedated with diazepam. Then, using the Cochet-Bonnet esthesiometer (Luneau Ophtalmologie, Chartres, France), the corneal sensitivity measurement device, corneal sensitivity was measured in 0.5% tetracaine- or 0.4% oxybuprocaine-treated rats. After ocular anesthetics, the rats received one or more tested substances (BPC, L-arginine, L-NAME), depending to which group the rats were randomized. Briefly, Cochet-Bonnet esthesiometer consists of nylon monofilament that can be pulled out and produces a pressure force at its top which is inversely proportional to the length of the elongated portion of the monofilament. The nylon filament is 0.12 mm in diameter and is 6 centimeters long. Corneal sensitivity testing started with a gentle touch of the fully extended tip of the esthesiometer perpendicular to the cornea and applying a small force to finely distort the filament. If the rat blinked, it was recorded as a positive response. If the blinking response was absent, filament length was reduced by 1 centimeter and the procedure was repeated until a positive response was obtained. The absence of the positive response when the filament length is 1 centimeter is defined as a complete corneal block. The length of filament in centimeters that caused positive response was recorded. In case of complete block, the value 0 was recorded. Corneal sensitivity tests were performed initially before the corneal anesthesia, and later in 5 minute intervals until full sensitivity was restored. Results: In both tetracaine and oxybuprocaine subgroups shortening of both complete corneal anesthesia (T1) and initial sensitivity restoration time (T2) were evident in groups treated with BPC 157. Tetracaine: T1: control 59 ± 5,2 min, BPC 45 ± 4,6 min, p < 0,001, T2: control 109 ± 12,5 min, BPC 94 ± 7,0 min, p = 0,008, Oxybuprocaine: T1: control 64 ± 5,7 min, BPC: 51 ± 5,0 min, p < 0,001, T2: control: 126 ± 3,9 min, BPC: 106 ± 7,4 min, p < 0,001. Anesthesia shortenings were also evident in groups treated with L-arginine, while in L-NAME treated groups anesthesia was prolonged. Conclusion: BPC 157 effectively shortens rat’s corneal anesthesia after topically applying local anesthetics. Its mechanism of action is nitric oxide mediated. Based on the study data we showed that BPC 157 can be used as a local anesthetic’s antagonist on the rat’s cornea. |
