Effects of prenatal alcohol exposure on the fetal and pups pancreas of albino Rats
Background: The pancreas is a mixed exocrine and endocrine accessory gland of the gastrointestinal tract located in the upper abdomen and connected to the duodenum. Its endocrine part produces important hormones such as insulin, glucagon and somatostatin while the exocrine part produces pancreatic juices containing digestive enzymes. Alcohol usage is known to interfere with oxidative dehydrogenate pathway that cause injury to the pancreatic tissues. However, the structural alterations resulting from exposure to alcohol have not been fully elucidated. It is also not known, how alcohol exposure to the pancreas during critical periods of development would affect its growth. Objective: The objective of this study is to identify and analyze the qualitative and quantitative changes in the fetal and pups pancreas following inutero exposure to alcohol. Study design: The study was a case control experimental study Materials and methods: A total of 100 pregnant albino rats were used in this study and they were divided into 10 control and 90 experimental subjects. The 90 rats in the experimental group were divided into three broad study categories of 30 rats each as Low (2.Sgms/kg/Bw), Medium (Sgms/kg/Bw), and High (6.Sgms/kg/Bw) dose treatment groups. The 30 rats in each of the three broad study categories were further subdivided into three sub groups of 10 rats each to march with the three trimester in a gestation period as TMI (GD 1 to 20), TM2 (GD 7 to 20) and TM3 (GD14-20). Each group of 10 rats was further sub-divided into prenatal and postnatal groups of 5 rats each. Both the control and experimental group received a standard diet containing 72% carbohydrates, 12% lipids, 20% proteins, 54mg/Kg/Bw zinc and water was provided ad-libitum.Pregnant animals were euthanized with an overdose of sodium pentobarbitone and perfused with 5% Zenkers solution for light microscopy and 4% phosphate buffered glutaldehyde for electron microscopy. The pancreas of fetuses and pups were dissected out and processed for light and electron microscopy for both morphological and morphometric analysis. Data analysis: Data were analyzed using the Statistical Package for Social Sciences (SPSS) for Windows Version 11.5 Chicago Illinois, and statistically tested using one way analysis of variance (ANOVA). Group means with a significance F-value (p<0.01 or 0.05) were further tested by Sheffes' multiple comparison procedure. Comparison on morphometric parameters between the control and the experimental groups were done by Mann-whitney T -test. The - Scheffe' Family Confidence Coefficient (SFCC) was applied as an expression of the confidence that all comparisons made among the sets of groups means were correct. Results: The effects of prenatal alcohol exposure depicted a wide range of teratogenic outcomes that were seen to be sustained from prenatal to postnatal life. Morphologically, the acini and islets depicted irregularly arranged clusters with reduced cellular counts per islet and per acini cluster. The sizes, shapes and cell compositions also depicted mixed population of 'mature' and 'immature' cells in a cluster with the latter type predominating in the alcohol treated groups. In the exocrine pancreas there was also delayed acini canalization, increased basophilia, reduced zymogen granules and increased fibrosis in the inter-acinar spaces. There was disaggregation of the islet clusters and reduction in the mean cellular counts per islet. The ducts were also disorganized and depicted plug formation. Ultrastructurally, the acinar cells, and the islet cells including the Beta, Alpha, PP-cells and D-cells revealed mixed populations of immature cells with reduced cytoplasmic granules, increased cytoplasmic lipid droplets, degeneration of the membrane bound organelles, and cytoplasmic vacuolations. Quantitatively, the mean volume density of acini (Vva) , the mean volume density of islets (V vis) and the mean volume density of blood vessels and ducts (VvBvD) in the alcohol treated groups significantly (P<O.OS) reduced while the volume density of fibrous connective tissue stroma (V fCTs) significantly increased when compared with the control. At moderate alcohol doses (MAG) and with exposure in the first trimester (TM1), alcohol caused 43.1 % increase in stromal tissue deposition, 41 % reduction in acini mass, 27% reduction of islet mass, and 38% reduction of beta-cell mass. It also caused 23% reduction in total islet volume, 45% reduction in total beta-cell volume, and 32% reduction in the volume-weighted mean islet volume in the fetal pancreas. Conclusion: The findings of this study show that prenatal alcohol exposure has both qualitative and quantitative teratogenic effects on the fetal pancreas that are sustained postnatally. These prejudicial effects of inutero alcohol exposure are also dose and time dependant. The high alcohol dose of 6.5mgs/Kg/Bw at first and second trimester presents the best 'window of opportunity' for expression of alcohol teratogenesis on the pancreas of albino rats. Such an effect of alcohol to the pancreas of children born to alcoholic mothers therefore suggest a predisposition to pancreatic disorders in postnatal life.