RESUMEN
We carried out computer morphometry in regenerates of planarians Dugesia tigrina. The blastema growth was analyzed in fragments of planarians after their fission and after transverse transection at different body levels. The blastema was growing at a higher rate on tail fragments than on the head fragments and the growth rate was the higher, the closer the transection was to the head end. After fission, the blastema was growing at a slower rate than after transection in the fission zone. The growth of adjacent blastemas formed on both sides after fission or transection proceeded at different rates as a function of new body polarity.
Asunto(s)
Planarias/fisiología , Regeneración , Animales , Cabeza/crecimiento & desarrollo , Morfogénesis , Planarias/anatomía & histología , Planarias/crecimiento & desarrollo , Cola (estructura animal)/crecimiento & desarrolloRESUMEN
Intracerebroventricular injections of the alpha 2-adrenoreceptor agonist clonidine (1, 10, and 100 nmole) produced a dose-dependent decrease in the low-frequency (1.5-3.0 Hz) EEG components and increase in the EEG theta-rhythm (4.3-7.2 Hz) in freely moving rats with chronically implanted electrodes in the cortex and a cannule in the lateral ventricle. The beta-frequency EEG components (20.8-26.5 Hz) were stimulated by smaller doses of clonidine and reliably inhibited by the maximum doses. The alpha 2-adrenoreceptor antagonist yohimbine potentiated the effect of clonidine in the theta- and beta-ranges. The D1-dopaminergic receptor agonist SKF-38393 (100 nmole) reduced EEG intensity in the 1.9-2.5 and 9.3-13.8 Hz and increased intensity in the 4.9-5.7 and 20.3-26.5 Hz regions. Preliminary injection of the D1-antagonist SCH-23390 prevented from the agonist effects in the high-frequency part of the spectrum. The possible participation of the pre- and post-synaptic dopaminergic D1- and alpha 2-adrenergic receptors in the EEG profile variation under the action of the above agents is discussed.