Synaptic and non-synaptic immunolocalization of GABA and glutamate acid decarboxylase (GAD) in cerebellar cortex of rat.

The existence of a large number of GABA receptors in the cerebellar molecular layer, and the observation of numerous punctate immunoreactive deposits of GABA synthesizing enzyme (GAD) throughout this layer, could indicate the existence of numerous axon terminals that may be involved in neurotransmission modulated by GABA. These axon terminals may be different from those considered classically as cerebellar GABAergic axon terminals. Therefore, we have reinvestigated the localization of GABA- and GAD-immunoreactivities in the cerebellar cortex of the rat with the PAP method, using different antisera obtained from rabbits immunized with GABA, baclofen and GAD. The results observed in our investigation have demonstrated GABA- and GAD-immunoreactivities in the axon terminals considered classically as GABAergic, as well as in others which, until now, have not been considered GABAergic. This fact leads us to think that the distribution of GABA or molecules structurally similar to GABA is far more extended than previously thought in the cerebellum. We have also observed both GABA- and GAD-immunoreactivities within dendrites and glial cells. These facts suggest us a possible extrasynaptic release of GABA.

Presence of meprobamate-like molecules in rat neuromuscular junction. Immunohistochemical demonstration at light- and electron-microscopic levels.

The localization of meprobamate-like (MPB-like) molecules in the neuromuscular junction of rats has been investigated at light- and electron- microscopic levels with the peroxidase-antiperoxidase (PAP) immunohistochemical method, using a purified antiserum obtained from rabbits immunized with a meprobamate-bovine serum albumin (MPB-BSA) conjugate. The immunoreaction was found surrounding synaptic vesicles and in protuberant deposits situated in the post-synaptic membrane. These facts suggest the existence of endogenous MPB-like molecules in neuromuscular junction and that the immunostained protuberant deposits should mark the receptors of those molecules.

Ventricular labyrinths of the ependyma adjacent to the hypothalamic paraventricular nucleus in the turtle Mauremys caspica.

Labyrinthic recesses projecting to the subependymal tissue have been observed in the ependyma of the III ventricle in close relation to the neurons of the hypothalamic paraventricular nucleus in the turtle Mauremys caspica. There seems to be evidence of a direct contact between the paraventricular nucleus neurons and the cerebrospinal fluid whose physiological significance is discussed in the present work.

Altered structures in the cytoplasm of the ependymal cells next to the periventricular nucleus of the turtle Mauremys caspica.

In the apical cytoplasm of some ependymal cells of the Hypothalamic Periventricular Nucleus of the turtle Mauremys caspica large amount of cell structures of difficult diagnose are found. Their morphology is variable seeming to correspond to cell organelles in a process of degeneration, characteristic feature of the high metabolic activity in the ventricular barrier. Their possible physiological significance is discussed in the present work.