Polyamine and histopathological changes after unilateral endotoxin-induced uveitis and its contralateral effects

The polyamines putrescine, spermidine and spermine are essential for normal cell function and proposed to be involved in inflammatory reactions. The polyamines were measured bilaterally in rabbit aqueous humor after unilateral endotoxin-induced uveitis. The contralateral eyes were injected with saline or not touched. Aqueous protein levels and leukocytes were determined and a histological evaluation was performed. Protein, leukocytes, putrescine and spermine increased in the treated eyes, but not in the untouched eyes. When saline was injected in the contralateral eye, a small increase in spermine was seen. Spermidine decreased first, but increased later, in both the endotoxin-injected and the other eye. Histopathologically, the treated eyes showed an infiltration of leukocytes, vasodilatation and in some cases optic nerve involvements. A mild reaction was also seen in the unchallenged contralateral eyes. The results show that polyamines might serve as a marker for acute inflammation in the eye and that the mechanism of putrescine and spermine induction is different from the one of spermidine. Polyamines are suggested to play a role in the cellular immune response.