María del Carmen Juárez Gutiérrez

Influence of pipecolic acid on the release and uptake of [3H]GABA from brain slices of mouse cerebral cortex

Recently, pipecolic acid (PA) has been involved in the functioning of the GABAergic system. In the present work we have studied the effect of PA on GABA uptake and release in cerebral cortex slices. PA (100 μM) was able to increase the release of [3H]GABA (90%) stimulated by mild depolarization with 15 mM potassium. If during the labeling of the tissue with [3H]GABA, β-alanine was present, PA also enhanced the release (42%). However, when nipecotic acid was present instead β-alanine, no stimulation of [3H]GABA release by potassium was observed neither in the control nor in the presence of PA. Spontaneous release was not affected by PA in any of the experimental conditions tested. In uptake experiments, only when β-alanine was present in the medium PA significantly diminished the uptake (36%) of [3H]GABA. These results suggest that the effect of PA is mostly at the presynaptic level, inhibiting the neuronal GABA uptake and/or enhancing its release.

Immunological approach to the study of neurohumoral sleep factors: Effects on REM sleep of antibodies to brain stem proteins

Abstract Proteins were collected for several months from the reticular formation of some 40 cats. The sodium dodecyl sulfate electrophoretic profile showed eight visible bands. Rabbits were inoculated with these proteins four times at weekly intervals in order to produce antibodies. Antibodies were also produced against cat serum proteins and cat serum albumin. These antibodies were tested for their effects on the sleep-wake cycle of another group of cats. The results of these experiments showed that the anti-reticular formation (MRF) antibodies and not antiserum or antialbumin antibodies, produced a specific decrease in rapid eye movement (REM) sleep without altering slow-wave sleep. It was also observed that when the anti-MRF antibodies were incubated with MRF proteins, the effect was lost, but that it persisted when they were incubated with serum protein only. It was also noted that the reduction in REM sleep was the result of an increase in the latency and a decrease in the frequency of REM periods, rather than in the duration of individual periods. In addition, the antibodies decreased some of the phasic elements of REM sleep such as multiple-unit and eye movement bursts. These experiments present the first direct evidence suggesting that specific protein molecules play an important role in triggering REM sleep.