A. Marino

Adrenomedullin and ocular inflammation in the rabbit

Adrenomedullin administered peripherally in the rabbit (at doses of 1.25, 2.5 and 5 microg/kg ) caused a dose-dependent conjunctival hyperemia accompanied by an increase of inflammatory cell number and prostaglandin E(2) concentration in the aqueous humor, and of uveal vascular response and myeloperoxidase activity. The inflammatory effect of the peptide, injected at the dose of 5 microg/kg, was abolished by pretreatment with the inhibitor of nitric oxide synthase, N(G)-nitro-L-arginine methylester (50 mg/kg, i.v.). Moreover, the i.v. pretreatment with the calcitonin gene-related peptide 8-37 fragment (calcitonin gene-related peptide, CGRP-(8-37), 2.5 microg/kg), receptor antagonist of CGRP, did not inhibit the conjunctival hyperemia. In contrast, the i.v. pretreatment with the adrenomedullin receptor antagonist, adrenomedullin-(22-52) fragment (2.5 microg/kg), abolished adrenomedullin-induced ocular inflammation. These results suggest that adrenomedullin causes conjunctival hyperemia, and this effect involves the nitric oxide system acting through specific adrenomedullin receptors.

Biochemical changes induced by pyrphenoxone in the lens of rabbits and rats

The xanthomatine analogue, pyrphenoxone, which is known to diminish the incidence of cataract in animals and in man, was applied in two different in vivo models of cataract induced in rabbits by tryptophan-free dietary regimen and in rats by hypergalactosemic diet. The drug was also applied at different concentrations in an in vitro model of cataract. It was found that soluble proteins and sulphurated amino acids of the lens in all in vivo and in vitro models of cataract were higher after pyrphenoxone was applied. Furthermore, the drug treatment was followed by a dose-dependent increase in reduced glutathione content in the lens of rabbits and rats. The same was found in the in vitro model of cataract. These results suggest that pyrphenoxone may act by inducing various biochemical changes that lead to a protection of lens against oxidative processes.