Insulin in the vitreous of the normal and streptozotocin-induced diabetic rat

• Published in: Peptides (New York, N.Y. : 1980) Vol. 13; no. 4; pp. 671 - 675
• Main Authors: Shires, Thomas K., Braddock, Kenneth J., Pulido, Jose S.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.07.1992; Elsevier Science
• Subjects: Albumin; Animals; Biological and medical sciences; diabetes mellitus; Diabetes Mellitus, Experimental - metabolism; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Enzyme-Linked Immunosorbent Assay; IgG; Insulin; Insulin - analysis; Insulin - metabolism; Insulin - pharmacokinetics; Iodine Radioisotopes; Male; Medical sciences; Rats; Rats, Sprague-Dawley; Reference Values; Serum Albumin - pharmacokinetics; Streptozotocin; Vitreous; Vitreous Body - chemistry; Vitreous Body - metabolism; vitreous humor; IgG; Albumin; Vitreous; Insulin; Streptozotocin; Endocrinopathy; Pancreatic hormone; Rat; Diabetes mellitus; Rodentia; Vitreous body; Eye; Visual system; Vertebrata; Experimental disease; Mammalia; Animal
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/0196-9781(92)90171-X

Insulin has been detected by ELISA in the vitreous of the normal and streptozotocindiabetic rat at levels for both about 1% of those in serum. 131I-labeled insulin, administered to conscious rats via an indwelling cannula in the right atrium, was found to cross the blood-ocular barrier into the vitreous. Autoradiographic gel analysis showed the peptide was transferred as an intact molecule. Vitreous insulin levels reflected serum levels as seen in relatively constant vitreous-to-serum insulin ratios over a wide range of serum insulin concentrations. The rate of blood-to-vitreous passage of insulin was about the same in normal as in diabetic rats ( fasting serum glucose≥21 mM ). At least a portion of vitreous insulin is therefore of pancreatic origin, and retinal tissue in the normal and diabetic animal is thus accessible to circulating hormone. The blood-ocular barrier is unaltered in streptozotocin diabetes with regard to insulin passage.