Corticotropin-releasing factor and intraocular pressure

Area of Science:

• Neuroendocrinology
• Ophthalmology

Background:

• Corticotropin-releasing factor (CRF) is a key regulator of the stress response.
• The role of centrally administered CRF in modulating intraocular pressure (IOP) is not fully understood.

Purpose of the Study:

• To investigate the effects of central CRF administration on IOP in conscious rabbits.
• To determine the time course and dose-dependency of CRF-induced IOP changes.
• To elucidate the involvement of ocular sympathetic nerves in the CRF response.

Main Methods:

• Ventriculocisternal perfusion of ovine CRF in conscious male New Zealand albino rabbits.
• Administration of various CRF doses (0.01-0.33 µg/min) for 1 hour.
• Assessment of IOP changes over time.
• Evaluation of CRF effects following superior cervical ganglionectomy.

Main Results:

• Central CRF administration at 0.1 or 0.33 µg/min caused an acute IOP decrease of 2.5 mmHg lasting 30 minutes.
• Higher CRF doses (≥0.033 µg/min) induced a delayed ocular hypotension starting 20 hours post-perfusion and lasting 2 days.
• Intravenous CRF injection did not alter IOP.
• Superior cervical ganglionectomy abolished the acute IOP reduction but not the delayed effect.

Conclusions:

• Centrally administered CRF elicits both acute and delayed reductions in IOP.
• The acute IOP effect of CRF is mediated centrally and involves ocular sympathetic nerves.
• CRF represents a novel pathway influencing intraocular pressure regulation.