Elevated levels of vasoactive intestinal peptide in the eye and urinary bladder of diabetic and prediabetic Chinese hamsters

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Abstract
The eyes and urinary bladder of non-diabetic, prediabetic and diabetic Chinese hamsters were evaluated by radioimmunoassay and immunocytochemistry to determine the content and distribution of vasoactive intestinal peptide (VIP). The average concentration of VIP was increased in the eyes of all diabetic (pmol/g = 68%, pmol/organ = 50%) and prediabetic (pmol/g = 152%, pmol/organ = 115%) hamsters compared with age-matched non-diabetic animals. Immunocytochemistry showed that the elevation of VIP was primarily related to greater intensity of fluorescence of the nerve fibres in the vasculature of the choroid. The average content of VIP in the urinary bladder was greater in diabetic animals only on the basis of pmol/organ (135%) and in prediabetics on the basis of pmol/g (87%) compared with non-diabetic animals. Qualitative immunocytochemistry suggested that the elevated level of VIP was related to a larger distribution of nerve fibres in the urinary bladder of diabetic hamsters. The high level of VIP in the eyes and urinary bladder of diabetic and prediabetic hamsters is an interesting observation which should receive further study to determine whether it is an aetiological agent underlying the pathogenesis of ophthalmic complications and neurogenic bladder or the result of some pathological process which affects these organs.