Effect of ovariectomy and female sex hormones administration upon gastric ulceration induced by cold and immobility restraint stress.

OBJECTIVE: To investigate the protective effects of estrogen and progesterone administrations on gastric mucosal barrier of rats applied ovariectomy, cold and immobility stress. METHODS: Seventy female Wistar rats, obtained from Medical Science Application and Research Center, Dicle University, Turkey on the year 2004, were divided into 10 separate groups (n=7). Nothing was applied to the animals of Group 1 (control); bilateral ovariectomy was performed on the animals of the Groups 2, 4, 5, 6, 7, 8, 9, and 10. Groups 5 and 6 was applied 5 mg/kg 17beta-estradiol and groups 7 and 8 was applied 10 mg/kg progesterone for 7 days. The animals in the Groups 9 and 10 were applied 2.5 mg/kg 17beta-estradiol and 5 mg/kg progesterone during 7 days. The animals in the groups 3, 4, 6, 8 and 10 were exposed to cold and immobility stress for 4 hours at 4degrees celsius. RESULTS: The levels of mucus and phospholipids were decreased in the rats applied ovariectomy and stress as compared to the control groups (p<0.001). The increase determined the mucus and phospholipids levels in estrogen and progesterone administered rats as compared to stress applied group (p<0.001). While the cold and immobility stress causes important damages in gastric mucosa, estrogen and progesterone administrations has protective effects in ovariectomized rats. CONCLUSION: The estrogen and progesterone administration prevents the stress that caused decrease in the levels of mucus and phospholipids, thus females are more resistant to gastric ulcer rather than males due to their sex hormones.

Histopathological effects in tissues of snail Lymnaea stagnalis (Gastropoda, Pulmonata) exposed to sublethal concentration of Thiodan and recovery after exposure.

Histopathological alterations induced by Thiodan in three tissues, namely, digestive gland, foot and mantle, of the freshwater snail Lymnaea stagnalis were investigated. Specimens of Lymnaea stagnalis were exposed to 0.36% and 0.72% Thiodan 35 EC, a commercial grade of endosulfan, for 96 h followed by a recovery period of 30 days. Thiodan caused significant dose dependent histopathological changes in all the tissues of the snail. Irreversible necrotic changes occurred in the digestive gland of the snail following Thiodan exposure. Degenerative changes in the muscle fiber of the foot, protein and pigment cells of the foot and the connective tissue element of the mantle were recovered after 30 days of recovery of the snail in pesticide-free freshwater.

The effects of endosulfan on the great ramshorn snail Planorbarius corneus (Gastropoda, Pulmonata): a histopathological study.

In this study the great ramshorn snail (Planorbarius corneus), one of the most abundant gastropod of Turkish limnic systems, was investigated to determine the histopathological effects of endosulfan on the digestive gland, foot and mantle under laboratory conditions. Samples were collected from small artificial pools in Karaot at Gelendost-Isparta (southwest of Turkey), where agricultural activities are widespread. The snails were exposed to two sublethal concentrations of endosulfan (0.4 and 0.8 mg/l) for periods of 10, 20 and 30 days. Fifteen snails were kept in 2.5 l glass jars containing dechlorinated tap water and exposed under semi-static test (daily exchange of test water). All the testing was carried out on adult specimens, and snails were maintained on a photothermal period with 16 light hours at 22 +/- 2 degrees C. The histopathological examinations revealed the following changes: amoebocytes infiltration, dilatation in hemolymphatic spaces between the tubules, degeneration of cells, abnormal lumen, necrosis of cells and atrophy in the connective tissue of digestive gland; desquamation of the epithelium cells, changes in the number of mucocytes and protein gland cells, lipid vacuolus and atrophy of the columnar muscle fibers of the foot and mantle tissues. Pycnotic state of cells was also seen in the mantle tissues. Endosulfan caused significant histopathological alterations in the digestive gland, foot and mantle tissues of the snail, irrespective of concentrations of the pesticide and its exposure periods. The results are discussed, particularly in comparison to those of other aquatic organisms.