title: Ocular Erythropoietin Penetration after Subconjunctival Administration in Glaucomatous Rats.
abstract: OBJECTIVE
  The present study aimed to determine whether the subconjunctival administration of recombinant human erythropoietin (rHuEPO) reached the retina in glaucoma conditions. After subconjunctival rHuEPO administration, in a rat glaucoma model, erythropoietin (EPO) distribution in the rat's retina was studied by immunohistochemistry.
  
  
  METHODS
  Female Wistar Hannover albino rats (n = 15) were divided into 2 groups, control (n = 3) and treated (n = 12). The animals' unilateral glaucoma was induced by coagulation of episcleral veins, under general anaesthesia. After vein coagulation, 1,000 IU of rHuEPO were administered by the subconjunctival route to the treated group (n = 12). The control group (n = 3) received only a subconjunctival saline injection. The contralateral eye of each animal remained untouched. Treated group animals were euthanized at different time points, i.e. days 1, 3, 7 and 14. Bilateral enucleation was performed, and EPO distribution in the rat's retina was assessed by immunohistochemistry.
  
  
  RESULTS
  Glaucoma was confirmed by results of repeated intraocular pressure measurements over the experimental period. In the test group, EPO was identified in different neuroretinal cells, showing a stronger immunostaining signal during the first 2 time points in the retinal ganglion cell (RGC) layer. EPO protein was still present on day 14 after the subconjunctival injection. EPO was not detected in any of the control eyes or in any contralateral eye of the treated group.
  
  
  CONCLUSIONS
  When administered subconjunctivally to glaucomatous eyes, rHuEPO reached the RGC layer and was still present at least 14 days after administration. The subconjunctival route was shown to be a promising alternative for ocular EPO delivery in glaucomatous conditions in a rat animal model.
authors.affiliation: Departamento de Clx00ED;nica, CIISA, Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Resende
authors.forename: Berta
authors.initials: B
authors.lastname: São Braz
authors.forename: Esmeralda
authors.initials: E
authors.lastname: Delgado
mesh_terms: D000818:Animals; D003228:Conjunctiva; D004195:Disease Models, Animal; D004921:Erythropoietin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D005901:Glaucoma / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D007150:Immunohistochemistry; D007267:Injections; D007429:Intraocular Pressure / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004921:Erythropoietin