MALDI imaging mass spectrometry revealed atropine distribution in the ocular tissues and its transit from anterior to posterior regions in the whole-eye of rabbit after topical administration

PLoS One. 2019 Jan 25;14(1):e0211376. doi: 10.1371/journal.pone.0211376. eCollection 2019.

Abstract

It is essential to elucidate drug distribution in the ocular tissues and drug transit in the eye for ophthalmic pharmaceutical manufacturers. Atropine is a reversible muscarinic receptor used to treat various diseases. However, its distribution in ocular tissues is still incompletely understood. Matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) evaluates drug distribution in biological samples. However, there have been few investigations of drug distribution in ocular tissues, including whole-eye segments. In the present study, we explored the spatial distribution of atropine in the whole-eye segment by MALDI-IMS, and then evaluated the changes in atropine level along the anterior-posterior and superior-inferior axes. A 1% atropine solution was administered to a rabbit and after 30 min, its eye was enucleated, sectioned, and analyzed by MALDI-IMS. Atropine accumulated primarily in the tear menisci but was found at substantially lower concentrations in the tissue surrounding the conjunctival sacs. Relative differences in atropine levels between the anterior and posterior regions provided insights into the post-instillation behavior of atropine. Atropine signal intensities differed among corneal layers and between the superior and inferior eyeball regions. Differences in signal intensity among tissues indicated that the drug migrated to the posterior regions via a periocular-scleral route. Line scan analysis elucidated atropine transit from the anterior to the posterior region. This information is useful for atropine delivery in the ocular tissues and indicates that MALDI-IMS is effective for revealing drug distribution in whole-eye sections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Topical
  • Animals
  • Atropine / analysis*
  • Atropine / metabolism
  • Chromatography, High Pressure Liquid
  • Eye / chemistry*
  • Eye / metabolism
  • Eye / pathology
  • Male
  • Rabbits
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization*
  • Tissue Distribution

Substances

  • Atropine

Grants and funding

This study was supported by MEXT/JSPS KAKENHI Grant Number JP15H05898B1; Imaging Platform supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan; and AMED under Grant Number JP18gm0910004. Santen Pharmaceutical Co. Ltd. provided support in the form of salaries for NM, T. Mochizuki, HM, and T. Matsugi, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.