Increased sensitivity to 5-hydroxytryptamine due to intraventricular administration of 5,6-dihydroxytryptamine

The possibility that intraventricular administration of 5,6-dihydroxytryptamine (5,6-DHT) can cause a development of denervation hypersensitivity to central 5-hydroxytryptamine (5-HT) was examined in rats with special reference to the pituitary-adrenocortical functions. Pretreatment with intraventricular injection of 5,6-DHT itself did not affect the basal concentrations or stress-induced increases of plasma B. The same pre-treatment, however, elicited augmented responses to subcutaneous injection of 5-HTP, i.e. there was a significant rise in the concentrations of plasma B as compared with those in the controls. These results suggest a development of denervation hypersensitivity to 5-HT following intraventricular injection of 5,6-DHT.

[A simplified method for determination of biochemical marker genes in inbred strains of mice (author's transl)]

A rapid method is described for the determination of biochemical variants of mice by Titan III cellulose acetate electrophoresis. Variants examined were hemoglobin beta-chain, serum esterase-1, malic enzyme (supernatant form), and isocitrate dehydrogenase (supernatant form). The present procedure can be recommended as a simplified method to analyze biochemical variants for checking of marker genes in inbred strains of mice.

The effects of microinjection of carbachol or hemicholinium into the amygdala on the levels of plasma and adrenal corticosterone in rats

Microinjections of 0.4 microgram of carbachol into the amygdala caused a rise of corticosterone (CS) in the morning when the prestimulating level of CS was lower. But the same procedure with a larger dose had no effect in the afternoon, when the prestimulating level of CS was higher.

Ultrastructural studies on the secretory cycle of the neurosecretory cells and the formation of Herring bodies in the paraventricular nucleus of the rat

The ultrastructure of the neurosecretory cells in the paraventricular nucleus of the normal male rat was studied by electron microscopy during various functional states. Four morphologically distinct types of neurosecretory cells were observed. It appears that they do not represent different classes of cells but different phases of secretory activity of a single cell type. The perikarya of the neurosecretory cells show a definite cycle of formation and transportation of secretory granules. We have designated the phases of this cycle as: (1) phase of synthesis, (2) phase of granule production, (3) phase of granule storage and (4) phase of granule transport. The neurosecretory granules appear to be moved in bulk into the axons, forming a large axonal swelling filled with granules as a result of one cycle in the neurosecretory process. Thus it may be postulated that a secretory cycle in the perikaryon of the neurosecretory cell seems to result in the formation of a Herring body in its axon, and that its content is then conveyed to the posterior pituitary.