Muscarinic drugs affect cholinesterase activity and development of eye structures during early chick development

During neurogenesis, markers of the cholinergic system are present in the eye and visual cortex of vertebrates. In adult vertebrates, a role for these molecules, including muscarinic acetylcholine receptors (mAChRs), in eye growth non-accommodative regulation is also known. In order to understand the biological mechanisms triggered by the cholinergic system in these events, we analysed the effects of a cholinergic agonist (10(-4) M carbachol) and an antagonist (10(-4) M atropine) of the muscarinic receptors, on early chick development. To establish if the cholinergic system also plays a role in the regulation of early neurogenetic signals, the drug treatments were made at stage 5-6 HH, during the formation of the cephalic process. Specific effects on forehead, and in particular on eye development were found; carbachol treated embryos presented huge and well pigmented eyes, significantly different from controls. The eyes of atropine-exposed embryos presented anomalies with different phenotypes ranging from strongly affected features to normal-like appearance. Generally, the eyes were smaller as compared to the controls, with a number of anomalies, also in the normal-like phenotype, including retina and lens defects. In these structures, distribution of cholinesterase activities was checked by histochemical methods, and the amount of cells undergoing nuclear disgregation was revealed by DAPI staining. We propose that the drugs affected the known nervous and pre-nervous functions of the cholinergic markers, such as cell signalling during primary induction, and regulation of cell death by ACh receptors.     

Lymphocyte migration during the development of regional lymph node anergy in experimental tumor growth

The development of lymph node anergy in Wistar rats to growing Walker carcinoma 256 was studied in vitro using the 51Cr-release cytotoxicity assay. Cell-mediated cytotoxicity to the tumor peaked in draining lymph nodes 11 days after tumor transplantation. By 14 days, the regional lymph node had become anergic to the tumor at a time when cell-mediated cytotoxicity was still increasing in the more distal contralateral lymph node. Lymphocyte migration into resting, cytotoxic, and anergic lymph nodes was analyzed to determine if altered cell migration into the regional lymph node was associated with the development of anergy. Lymphocyte migration was found to be enhanced in both cytotoxic and anergic regional lymph nodes of tumor-bearing animals. It is concluded that lymph node anergy in this experimental tumor system is not related to changes in lymphocyte migration patterns; rather, it is the result of alterations in the microenvironment of the lymph node which prevents the expression of cytotoxic effector cells.     

Effect of splenic humoral factors on the cholinesterase activity of liver tissue and blood serum in experimental toxic hepatitis in rats

Activity of cholinesterase in the liver of rats with experimental toxic hepatitis decreases, while in the serum it remains unchanged. Introduction of splenin, a spleen preparation, normalizes indices of the cholinesterase activity, extract of muscles possessing no such property. Boiling-heated spleen preparation looses its activity. Activity of the studied enzyme remains unchanged both after splenectomy and splenin introduction to intact animals.     

Cytogenetic study of the blood cells and lymph nodes in the process of the development of experimental lympholeukosis in calves]

The karyotypes of peripheral blood lymphocytes were examined in 72 hour cultures in the process of the induced lymphatic leucaemia development in calves, as well as the karyotypes of one-layer transplantated tissue cultures of blood cells and lymph nodules of the same calves. The increase in hyperdiploid cell ratio in all investigated tissue cultures was detected.