Abstract
AC resemble stem cells and express histamine H1 and H2 receptors. We examined an effect of histamine on the generation of IC from nicotinamide‐stimulated AC and expression of H1 and H2 at different stages of this process. AC were isolated from human amnion (N=12) and cultured for 16 days using Okita's method with nicotinamide (10mM). Mean concentration ofC‐peptide (CCP) in the culture media was measured every 3 days as a marker of the secretion of insulin. At the same intervals the cultures were fixed and immunostained for H1 and H2. Quantitative morphometry was applied for evaluation of H1 and H2 expression. Influence of histamine (100microM) on CCP was studied in subgroups with/without H1 and H2 antagonists.C‐peptide was detected on Day 6 and CCP gradually raised until Day 12, then stayed at similar levels, 4,1‐fold higher than initially. Expression of H2 was unchanged (compared to control AC) until Day 9, then significantly decreased. Differences in H1 expression were not observed. Histamine produced significant increase in CCP, more evident after 6 days of culture than after 15 days. H2 blockade reduced histamine‐related increase of CCP, whereas H1 antagonist did not affect CCP. Nicotinamide‐induced, pancreatic differentiation of AC in vitro may be augmented by histamine acting on H2 receptors. Variable expression of H2 may define a time‐point, indicating involvement of histamine at earlier stages.
Published Version
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