Distribution and localization of histamine in bovine and rabbit eye

Histamine (HI) is present in various structures of the bovine and rabbit eye (retina, choroid, sclera) and in the optic nerve of both species. The amine levels in particular structures of either cow or rabbit are highly differentiated, as well as profile of HI distribution which differs markedly between both species, except only the retina structure (HI levels were between 70-80 ng per g tissue). In the bovine retina HI is stored in non mast cell compartment, while in the optic nerve at least 50% of the amine is of mast cell origin. Approximately 90% of the retinal HI was recovered in the P1 subcellular fraction. HI in the bovine retina is metabolized by methylation. The data are discussed in terms of a possible physiological role of HI in the retina.