Showing papers by "Sanford L. Palay published in 1982"

The Cerebellum : new vistas

Abstract: The present volume consists of papers prepared for a conference on the cerebellum which was held at the National Institutes of Health in Bethesda on 15 -17 May 1980. This was the first gen eral conference on the cerebellum since the 1972 symposium in Portland, Oregon, which was convened to celebrate the publica tion of the last volume of the Comparative Anatomy and Histolo gy of the Cerebellum by Larsell and Jansen. In organizing the 1980 Conference, we elected to emphasize ad vances in neuroanatomy over other aspects because, in our view, morphological investigation continues to playa large and essential role in the developing understanding of cerebellar func tion, and, despite the general impression that cerebellar anat omy is better known than any other part of the nervous system, our information on this topic is far from complete. N everthe less, the cerebellum offers the best model we have for analyzing the vertebrate central nervous system. The correlation of ana tomical, cytological, developmental, physiological, chemical, and pharmacological data on this relatively simple and uniform structure, which has persisted with remarkable conservatism through vertebrate evolution, still holds a rich store of answers to the most penetrating questions concerning the functional organization of the brain. Naturally, within the limits of time, space, and our resources we could not pretend to include every thing that has been learned about the cerebellum in the past decade."

Sagittal cerebellar microbands of taurine neurons: Immunocytochemical demonstration by using antibodies against the taurine-synthesizing enzyme cysteine sulfinic acid decarboxylase

Abstract: Taurine neurons in the cerebellum of rabbit, rat, and mouse were localized at the light microscope level by using polyclonal antibodies against cysteine sulfinic acid decarboxylase (CSADCase; EC 4.1.1.29), the enzyme responsible for the conversion of cysteine sulfinic acid to hypotaurine and of cysteic acid to taurine. The indirect peroxidase-antiperoxidase method was used on Vibratome sections and on serial sections of paraffin-embedded tissue. Intensification of CSADCase immunoreactivity was achieved by pretreatment of the animal with L-cysteine or L-cysteic acid intravenously 1-2 hr prior to perfusion. A combination of L-cysteic acid and demecolcine, which retards axoplasmic flow, was most effective in maximizing CSADCase immunoreactivity. Although these treatments intensified immunoreactivity in neurons, no more cells were reactive than in untreated controls. L-Glutamic acid did not increase CSADCase immunoreactivity but did increase immunoreactivity with antibodies against L-glutamic acid decarboxylase (GAD; EC 4.1.1.15), the synthetic enzyme for γ-aminobutyric acid. Specificity was established by negative results obtained with various control incubations including the use of CSADCase antiserum preabsorbed with the antigen. Taurine neurons of the cerebellar cortex are arranged in sagittal microbands, defined by intensely CSADCase-reactive Purkinje neurons and their axons and dendrites, together with stellate, basket, and Golgi cells and their processes. In the vermis there is a narrow midline band, flanked laterally by three wider bands on either side, each separated from the next by an unreactive zone. Although the zonal borders are sharp, the interzonal areas contain some CSADCase-immunoreactive axons but no cell bodies. The seven vermal bands are best observed in the anterior lobe. Others exist in the lateral hemispheres. The paraflocculus and flocculus contain numerous intensely immunoreactive neurons, and banding is difficult to discern. Lobule X of the vermis is also heavily endowed with taurine neurons. Numerous large and medium-sized deep cerebellar and vestibular nuclei are also immunoreactive. These observations indicate that cerebellar neurons are chemically heterogeneous but that neurons of similar chemical signature in the cerebellar cortex are organized into sagittal microbands. This corroborates our earlier evidence that Purkinje cells containing motilin and those containing both motilin and γ-aminobutyric acid are also arranged in vermal sagittal microbands. The midline vermal band contains Purkinje neurons with multiple neuroactive substances—taurine, γ-aminobutyric acid, and motilin. It remains to be determined how this chemical zonation in the cerebellar cortex relates to the banded afferent innervation from spinal, vestibular, reticular, and olivary sources.

Taurine in the mammalian cerebellum: Demonstration by autoradiography with [3H]taurine and immunocytochemistry with antibodies against the taurine-synthesizing enzyme, cysteine-sulfinic acid decarboxylase

Abstract: Taurine neurons and their dendrites and axons were visualized in the mammalian cerebellum by autoradiography, after in vivo injections of [3H]taurine directly into the cerebellar cortex or deep cerebellar nuclei, and by immunocytochemistry at the light- and electron-microscope levels with antibodies against cysteine-sulfinic acid decarboxylase (CSADCase; L-cysteine-sulfinate carboxylyase, EC 4.1.1.29). Uptake and sequestration of [3H]taurine labeled numerous Purkinje cell somata, primary dendrites, and axons; many granule cell somata, dendrites, and parallel fibers; stellate, basket, and Golgi cells; the larger neurons in all deep cerebellar nuclei; the largest neurons in the lateral vestibular nucleus; and, more rarely, Purkinje cell axonal terminals in the neuropil. The label at all sites was diminished by preinjection into the cerebellum of hypotaurine, p-chloromercuriphenylsulfonic acid, or β-alanine, and was virtually eliminated by strychnine. Immunocytochemical labeling with polyclonal antibodies directed against CSADCase, the enzyme responsible for the synthesis of hypotaurine from cysteine sulfinic acid and taurine from cysteic acid, had a similar distribution. In electron micrographs, immunoreactivity within Purkinje cell somata and dendrites was localized to the Golgi apparatus, the inner plasma membrane, and condensed nonmembranous foci (120 nm in diameter) marked by clumps of peroxidase reaction product. Large Nissl bodies were usually not CSADCase immunoreactive. Numerous immunoreactive granule cells, dendrites, and parallel fibers were recognized. Pretreatment of the animals with colchicine increased the intensity of CSADCase immunoreactivity but did not change the number or distribution of labeled cells. These experiments indicate that taurine is synthesized and involved in a specific uptake process by cerebellar neurons. Neuroglial cells do not synthesize taurine but some neuroglia take up [3H]taurine. These findings call for a reexamination of the physiological function of taurine in the cerebellum. A hypothesis is proposed that taurine may be involved in the regulation of calcium, in dendritic spike generation, and in the inhibition of impulse propagation in major Purkinje cell dendrites.

Inhibitory effects of motilin, somatostatin, [Leu]enkephalin, [Met]enkephalin, and taurine on neurons of the lateral vestibular nucleus: Interactions with γ-aminobutyric acid

Abstract: Motilin, [Met]enkephalin, [Leu]enkephalin, somatostatin, taurine, γ-aminobutyric acid (GABA), and glycine were tested for their effects on Deiters neurons of the lateral vestibular nucleus in rabbits. Iontophoresis was carried out with multibarrelled micropipettes. All four peptides and three amino acids produced depression of neuron firing. No facilitatory responses were observed. The depressant action of each peptide when iontophoresed alone was dose-dependent and was rapid in onset and recovery. Their characteristic actions suggest the possibility of their independent roles as strong inhibitors, although the experimental paradigm does not allow conclusions about the individual potency of each peptide. When GABA was administered together with motilin, [Met]enkephalin, or somatostatin, the effects of the peptide and GABA were additive, producing depression greater than that with application of either substance alone. When GABA was applied in conjunction with [Leu]enkephalin, more complex interactions were observed. At low iontophoretic currents, [Leu]enkephalin antagonized the action of GABA, producing a depression less than that of GABA alone and of considerably slower onset, suggesting an additional modulatory effect. These observations support the conclusion that all substances tested are chemical mediators in the lateral vestibular nucleus and [Leu]enkephalin may be a neuromodulator as well. Because recent immunocytochemical studies indicate that Purkinje cells in the cerebellar cortex are chemically heterogeneous and exhibit immunoreactivity for motilin, taurine, the enkephalins, and somatostatin, as well as for the GABA-synthesizing enzyme glutamic acid decarboxylase, it is suggested that the Purkinje cell projections to vestibular and cerebellar nuclei are multimodal in their chemical coding. The uniformly depressant action of the peptides and amino acids reported here is consistent with earlier observations that Purkinje cells exert an inhibitory influence on the vestibular and central cerebellar nuclei.

Coexistence in human and primate neuromuscular junctions of enzymes synthesizing acetylcholine, catecholamine, taurine, and gamma-aminobutyric acid.

Abstract: Coexistence of neurotransmitter-synthesizing enzymes choline acetyltransferase, cysteine sulfinic acid decarboxylase, tyrosine hydroxylase, and L-glutamic acid decarboxylase was demonstrated at human and primate neuromuscular junctions with specific antibodies directed against these enzymes. Motor end plates were identified in unfixed cryostat sections by standard cholinergic markers for acetylcholinesterase and the acetylcholine receptor. Each of the four transmitter-synthesizing enzymes was localized at end plates displaying these markers. The presence of any two of the four enzymes at a given end plate was established by (i) showing immunoreaction for one enzyme followed by elution and demonstration of immunoreaction for a second enzyme, and (ii) paired immunofluorescence with simultaneous demonstration of one enzyme with a rhodamine-labeled second antibody and of the other enzyme with a fluorescein-labeled second antibody. These findings imply that motor nerve terminals have the capacity for synthesizing not only acetylcholine but also taurine, catecholamines, and gamma-aminobutyric acid. These substances, in turn, may participate in the normal regulation of nerve-muscle interaction or be significant in specific disorders involving the motor unit.

Synthesizing enzymes for four neuroactive substances in motor neurons and neuromuscular junctions: light and electron microscopic immunocytochemistry

Abstract: Immunocytochemical evidence is presented for the existence of choline acetyltransferase (ChoAcTase), cysteine sulfinic acid decarboxylase (CSADCase), tyrosine hydroxylase (TyrOHase), and glutamic acid decarboxylase (GluDCase) in large motor neurons of the hypoglossal nucleus and the spinal cord and in nerve terminals of motor end plates in tongue and skeletal muscle of five mammalian species, including man. These enzymes, which are responsible for the synthesis of acetylcholine (AcCho), taurine, dopamine, and gamma-aminobutyrate (GABA), respectively, were detected by immunocytochemical studies with monoclonal or polyclonal antibodies raised against the enzymes. Electron microscopy of the neuromuscular junctions showed that the immunoreactivity in each case was confined to the cytoplasmic matrix of presynaptic nerve terminals. Immunoreactivity obtained for each enzyme antibody varied with the species. It was highest in fresh, unfixed muscle and lowest in aldehyde-fixed specimens. Negative controls were obtained with preimmune sera and antisera preabsorbed with pure ChoAcTase, CSADCase, or GluDCase antigen. Double-labeling studies with ChoAcTase antibodies and acetylcholinesterase (AcChoEase) antibodies, AcChoEase enzyme activity, or alpha-bungarotoxin binding indicated that ChoAcTase, AcChoEase, and AcCho receptors were colocalized at the same end plates.