Improved rapid method to check electrode localizations in the brain.

A modification of known rapid methods to check electrode localization in the brain is described: the essential point consists in immersing the brain, after fixation in 4 percent Formalin, in pure heptane at -30 degrees C for 5 hr. Unstained sections, cut with the freezing microtome, are placed uncovered on glass slides and photographed (in an enlarger, as if they were negatives) either wet, to obtain a contrast resembling Weil staining, or dry, to obtain a picture corresponding to Nissl staining.

Possible involvement of GABA in the central actions of benzodiazepines.

The effects of several benzodiazepines on a variety of nervous activities known or presumed to depend on GABA are presented and compared with those of agents that deplete or increase the level of endogenous GABA: antagonism of various convulsant agents in mice, enhancement of presynaptic inhibition in the spinal cord and the cuneate nucleus of cats, decrease of the spontaneous firing rate of cerebellar Purkinje cells in cats and rats, antagonism of bicuculine-induced depression of the strio-nigral-evoked potential in the cat, potentiation of haloperidol-induced catalepsy in rats, GABA-mimetic actions on drug-induced PGO-waves in cats and on eserine-induced circling in guinea pigs. Diazepam slightly increased the GABA level in the cat spinal cord and in the total brain of mice and rats; this increase does not seem to be due to an increase of GABA synthesis. It is concluded that benzodiazepines probably enhance presynaptic inhibition at all levels of the neuraxis and that this effect requires not only the presence of GABA but is also dependent on an activity of GABA-ergic neurons.

Cerebrally active small moiety from "taraxein-like" blood fractions.

A charged, amphoteric, smiall moiety has been separated from a "taraxein-like" blood fraction by electrodialysis throuighl ion exchange membranes. Cerebral bioassay shows that the activity of the blood extract is contained in the charged small moiety so that, as the activity in the charged compartment rises during electrodialysis, the activity in the feeding (extract) compartment falls.