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Aqueous humor dynamics associated with the phorbol ester-induced decrease in intraocular pressure in the rabbit

Takayuki Oka1, Toru Taniguchi2, Yoshiaki Kitazawa2

  • 1Research Laboratories, Senju Pharmaceutical Company, Ltd., Kobe, Japan. takayuki-oka@senju.co.jp.

Japanese Journal of Ophthalmology
|December 21, 2006
PubMed

Insights

Protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) injection in rabbits reduced intraocular pressure (IOP) by increasing uveoscleral outflow. This IOP-lowering effect may involve PKC activation.

Area of Science:

  • Ophthalmology
  • Pharmacology
  • Physiology

Background:

  • Intraocular pressure (IOP) is a critical factor in ocular health.
  • Protein kinase C (PKC) plays a role in regulating various cellular functions, including those in the eye.

Purpose of the Study:

  • To investigate the impact of phorbol 12-myristate 13-acetate (PMA), a PKC activator, on intraocular pressure (IOP) and aqueous humor dynamics.
  • To explore the potential of PMA as a therapeutic agent for managing IOP.

Main Methods:

  • Unanesthetized rabbits received intracameral injections of PMA (3-50 pmol).
  • Intraocular pressure (IOP) was monitored for 24 hours post-injection.
  • Aqueous humor dynamics, including aqueous flow and outflow facility, were assessed.

Main Results:

  • PMA induced a biphasic effect on IOP: a transient increase followed by a sustained decrease.
  • The IOP-lowering effect was dose-dependent and persisted even after indomethacin pretreatment.
  • PMA significantly increased uveoscleral outflow but did not affect aqueous flow or total outflow facility.

Conclusions:

  • Intracameral PMA administration effectively reduces IOP in rabbits.
  • The primary mechanism for IOP reduction is the enhancement of uveoscleral outflow.
  • PKC activation is likely involved in mediating the IOP-lowering effects of PMA.
Abstract

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