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Updated: Dec 10, 2025

Transconjunctival Approach for Injection into the Rat Optic Nerve
Published on: April 4, 2025
PnPP-19 Peptide as a Novel Drug Candidate for Topical Glaucoma Therapy Through Nitric Oxide Release
Carolina Nunes da Silva1, Lays Fernanda Nunes Dourado1, Maria Elena de Lima2
1Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte-MG, Zipcode 31270-901, Brazil.
Purpose:
Evaluation of PnPP-19 safety and efficacy in reducing the intraocular pressure (IOP) of animals with healthy (normotensive) and ocular hypertensive eyes. PnPP-19 is a synthetic peptide designed from Phoneutria nigriventer spider toxin PnTx2-6.
Methods:
Toxicity tests used chicken chorioallantoic membranes. Electroretinograms (ERGs) were recorded before and after administration of different doses of PnPP-19 on the eyes of Wistar rats. Histological sections of corneas and retinas were prepared. The efficacy of PnPP-19 in reducing IOP was evaluated for normotensive and ocular hypertensive animals using a tonometer. Ocular hypertension was induced in the right eye through injection of hyaluronic acid (HA) into the anterior chamber. ERG was recorded before and after glaucoma induction. The eyes were enucleated, and the corneas and retinas were histologically evaluated.
Results:
PnPP-19 showed no toxicity, being safe for ocular application. A single topical instillation of one eye drop of the peptide solution was able to reduce IOP, both in healthy and ocular hypertensive rats, for 24 hours, without eliciting any apparent toxicity. PnPP-19 is a nitric oxide inducer and the results suggest that it may improve the conventional outflow of aqueous humor (AH), preventing the progression of optic nerve degeneration.
Conclusions:
PnPP-19 has great potential to emerge as a promising drug for the treatment of ocular hypertension.
Translational Relevance:
We regard our findings as exciting progress in translational glaucoma research, combining drug discovery, natural product research, and pharmacology, which may contribute to the establishment of new therapies for the treatment of this disease.
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