Study of the effects of ocular hypotensive drugs on number of neurons in the retinal ganglion layer in a rat experimental glaucoma.
OBJECTIVE
We investigated the effects of antiglaucomatous drugs on neurons in the retinal ganglion layer (RGL) in an experimental model of elevated intraocular pressure (IOP).


METHODS
Three episcleral veins of rats with normal IOP were cauterized. Three months later, we examined the effects on the number of neurons in the RGL as well as in rats submitted to treatment with timolol, latanoprost, or brimonidine. The IOP was measured using a calibrated Tono-Pen XL tonometer before and immediately after cauterization and every 2 weeks for the following 3 months as well as immediately before perfusion.


RESULTS
The IOP was 14.85+/-0.65 mmHg in the control group, whereas it was 1.25-fold higher (33.5+/-1.06 mmHg) in the experimental group. After treatment, the IOP returned to baseline levels. The mean number of neurons per mm2 in the RGL was 33% lower in the experimental group (283+/-10 cells/mm2) compared with the control group (423+/-11 cells/mm2). In the groups treated with timolol, latanoprost, or brimonidine, the neuronal loss was less (331+/-10, 360+/-15, and 333+/-3 cells/mm2, respectively), although values did not return to baseline levels.


CONCLUSIONS
This experimental model provokes an immediate, constant, and prolonged increase in IOP and the application of hypotensive agents affords a certain degree of protection to neurons in the RGL.
Villena
Alicia
A
Department of Histology, School of Medicine, University of Málaga - Spain. avillena@uma.es
Diaz
Florentina
F
Vidal
Lourdes
L
Moreno
Mrcedes
M
Garcia-Campos
Jose
J
Perez De Vargas
Ignacio
I
D000287:Administration, Topical; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D000068438:Brimonidine Tartrate; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects; D004195:Disease Models, Animal; D005901:Glaucoma / Q000188:drug therapy*; D007429:Intraocular Pressure / Q000187:drug effects*; D000077338:Latanoprost; D008297:Male; D011461:Prostaglandins F, Synthetic / Q000008:administration & dosage; D011810:Quinoxalines / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000187:drug effects*; D055351:Retinal Neurons / Q000473:pathology*; D013999:Timolol / Q000008:administration & dosage; D014065:Tonometry, Ocular
D000959:Antihypertensive Agents; D011461:Prostaglandins F, Synthetic; D011810:Quinoxalines; D000068438:Brimonidine Tartrate; D000077338:Latanoprost; D013999:Timolol