Central effects of thyrotropin-releasing hormone and arginine vasopressin on intraocular pressure in rabbits.

Administration of either thyrotropin-releasing hormone (TRH) or arginine vasopressin (a-VP) into the rabbit third ventricle elevated intraocular pressure (IOP). IOP was increased 3.6 mmHg 45 min after TRH (10 ng/0.1 ml) administration and increased 6.4 mmHg 45 min following delivery of a-VP (5 micrograms/0.1 ml). Outflow facility and episcleral venous pressure were not altered by either agent. Estimated aqueous humor flow 45 min after third ventricle administration was increased 66% after TRH and 91% after a-VP delivery. Posterior chamber aqueous humor ascorbate was reduced 60 min after TRH administration. Pretreatment with either systemic or topical atropine prevented the TRH or a-VP induced increase in IOP. Body temperature (BT), which was unaltered after TRH administration, was elevated by third ventricle delivery of a-VP. The a-VP induced increase in BT was blocked by systemic pretreatment with either indomethacin or atropine.