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

Abstract

Summary. 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.Key words: VIP, radioimmunoassay, immunocytochemistry, eyes, urinary bladder, prediabetes, diabetic Chinese hamsters.Complications of the eye and urinary bladder have been documented in patients with diabetes mellitus and most animal models of this disease. With respect to the eye, lesions have been adequately described in the retina [1][2][3][4][5]. Although the specific type of lesion varies among animals and man, the vasculature of the eye is always adversely affected [5]. Several investigations have demonstrated that distension [6-9] and hypertrophy [10] concomitant with urine retention are characteristic of the urinary bladder of diabetic man and animals. Urinary bladder dysfunction is believed to be a product of diabetic autonomic neuropathy [11,12] which promotes impairment of detrusor muscle function [8,13]. Although it has recently been disputed [9], a reduction in cholinergic innervation [7,14] has been proposed as a possible mechanism which elicits bladder dysfunction. Despite intensive research, the primary aetiological agent(s) underlying the derangements in the eye and urinary bladder of diabetic man and animals remain under investigation.Vasoactive intestinal peptide (VIP) has been shown to be present in high quantities in the eye [15][16][17][18][19] and urogenital tract [20][21][22][23] of several species, including man. Due to its potent vasodilator activity [24] and its possible involvement in regulation of relaxation [25][26][27] and contraction [28] of the urogenital tract, it was of interest to determine whether concentration and/or distribution of this peptide are altered in the eye and urinary bladder of a suitable diabetic animal model. Since the spontaneously diabe...

Worldwide trends in prediabetes from 1985 to 2022: A bibliometric analysis using bibliometrix R-tool

“…Thereafter, 7,636 publications remained for analysis. The first article in the field of prediabetes was written by A R Dian and published in the journal "Diabetologia" (18). As shown in Figure 2, the number of articles each year has exhibited a sustained growth trend since 2005 and reached 876 in 2021.…”