Do beta-adrenoceptors and serotonin 5-HT1A receptors have similar functions in the control of intraocular pressure in the rabbit?

Serotonin 5-HT1A-type and beta-adrenergic receptors have similar molecular characteristics, which explains why certain substances like propranolol have affinities for both receptor types. Activation of 5-HT1A receptors leads to a decrease in intracellular cAMP levels whereas the opposite occurs for beta-adrenergic receptors. Both 5-HT1A and beta-adrenergic receptors exist in the rabbit ciliary processes. Topical application of the 5-HT1A agonist, 8-hydroxydipropylaminotetralin (8-OH-DPAT) reduces intraocular pressure (IOP). beta-Antagonists are also known to reduce IOP. It is postulated that substances which have an affinity for 5-HT1A and/or beta-adrenergic receptors and lead to a reduction in intracellular cAMP levels in the ciliary processes diminish IOP.