Effect Of Cadmium On The Distributive Density Of Gastrointestinal Endocrine Cells Of Carassius Auratus

Heavy metals pollution not only affect industrial and agricultural production, but also accumulate into the human body by the enrichment of the food chain, and cause serious harm to human health. Cadmium is a biotoxic environmental pollutant which accumulates in the body tissues such as the lungs, liver, kidneys, bones, reproductive organs and the immune system. The toxic effects of cadmium on organisms include nephrotoxicity, carcinogenicity, teratogenicity and endocrine disruption.In this study, we did a cadmium pollution research for freshwater fish in Han River first, including Cyprinus carpio, Mylopharyngodon piceus, Misgurnus anguillicaudatus, Carassius auratus, Channa argus, Silurus asotus, Hypophthalmichthys molitrix. Then adopted static method of laboratory simulation test, used Cadmium as experimental toxicant and Carassius auratus as experimental creature. We set up 3 concentration gradient groups and one blank control group, each group had 2 parallels. We have studied the organization and distributive density of gastrointestinal endocrine cells of Carassius auratus between control group and Cd2+ exposure group after 10 days, using the H·E and SABC immunhistochemical method.The results showed that the order of cadmium content in 3 organs of 7 fish species was that: liver> gill> muscle. The cadmium content in the gill and liver of all fish was excessive. The cadmium content in the muscle of loach and carp was excessive, others was under the standard.The digestive tract of Carassius auratus had the four layers: mucosa, submucosa, muscular layer and adventitia. Gastrin-IR cells, Somatostatin-IR cells and Vasoactive Intestinal PeptideIR cells were distributed throughout the digestive tract. The distribution density of GAS-IR and SS-IR were determined to be foregut> midgut> hindgut, and the differences in the three density gradients reached significant level. The distribution density of VIP-IR was same to GAS-IR and SS-IR, but the difference didn’t reached significant level. However, the Substance P-IR cells were distributed only in the midgut and Secretin-IR cells were distributed only in the foregut. After 10 days of Cd2+ exposure, the digestive tract of Carassius auratus have no obvious change in intestinal histology structure, but the density of digestive endocrine cells changed. With the increase of concentration of Cd2+, the density of GAS-IR cells and VIP-IR cells was on the rise, but the density of SS-IR cells, SP-IR cells and SCT-IR cells was on the decline. Compared with the control group, the increase of GAS-IR cells reached significant level in foregut and midgut. However, the increase of VIP-IR cells reached significant level only in hindgut. The decline of SS-IR cells reached significant level only in foregut, and the decline of SP-IR cells and SCT-IR cells reached significant level.The main conclusions suggested in this study were shown as follows: The freshwater fish of Han River were polluted by cadmium in Hanzhong. The cadmium content in some of them was excessive, and them cann’t be eaten.When the Cd2+ concentration in water is 5.00 mg/L or below, it caused no significant histological damage in the digestive tract of Carassius auratus after 10 days. The distributive density of gastrointestinal endocrine cells of Carassius auratus were changed in this study, the Cd2+ concentration has a significant correlation with the density of endocrine cells. The effects of Cd2+ on gastrointestinal endocrine cells has variety of regulatory mechanisms, not only controlled by the kidney toxicity and liver toxicity of cadmium, but also controlled by the regulation of endocrine cells each other.