Biomedical subjects

Y L Murashima

Publications and source records attributed to Y L Murashima.

22 records · Page 2Linked to original sources

PubMed1987

GABA concentration and GAD activity levels in normal and degenerated retinas from mice.

Freeze-dried sections (14 microns thick) were prepared from mice with normal (C57BL strain) and degenerated (C3H strain) retinas. GABA concentration and GAD activity were determined in the microsamples (1.8-20 ng dry weight) of retinal layers and sublayers, using an enzymatic amplication reaction, NADP cycling. GABA was distributed over all layers of normal retina with a broad concentration peak covering both inner nuclear and plexiform layers. In contrast, GAD activity was mostly localized in the inner plexiform layer. GABA concentration was similar in one-fourth of the sublayers of each inner nuclear or plexiform layer. GAD activity was highest in the innermost sublayer of the inner nuclear layer. An increasing gradient of GAD activity was present in the inward direction in the inner plexiform layer. In the degenerated retina, lacking in photoreceptors, the inner nuclear and plexiform layers remained, and GABA and GAD levels in these layers were similar to those in normal retina.

Animals↗

PubMed1986

Distribution of gamma-aminobutyric acid and glutamate decarboxylase in the layers of rat oviduct.

An enzymatic microassay method for glutamate decarboxylase (GAD) and gamma-aminobutyric acid (GABA) was improved to yield a high sensitivity and a low blank. The 20-microns thick freeze-dried sections (0.2-1.5 micrograms dry weight) were prepared from the oviduct and ovary of rat. The analysis of these microsamples by the improved method showed that, contrary to the previous observations, the rat ovary is devoid of GAD activity and contains a trace amount of GABA. Both are present abundantly in the oviduct. In the oviduct mucosa, significant GAD activity was found in the estrous phase, whereas the activity was nearly null during other phases of the estrous cycle. GABA concentration in the oviduct mucosa was 10-fold higher than in the cerebral cortex; its variation during the estrous cycle was not remarkable. In the muscle layer of oviduct, GAD activity had a low peak in the estrous phase and GABA concentration was almost constant during the estrous cycle. The denervation experiment showed that GAD is present in the nerve terminals innervating the oviduct.

Animals↗

PubMed1985

Glutamate decarboxylase activities in single vertebrate neurons.

An enzymatic microassay method for glutamate decarboxylase (GAD) and gamma-aminobutyric acid (GABA) was improved to a degree yielding high sensitivity and low blank. Single cell bodies of anterior horn cells and dorsal root ganglion cells were dissected out from the freeze-dried sections of rabbit and chicken spinal cords and Purkinje cell bodies from those of rabbit cerebellum. A minute amount of GABA, present in single neurons or synthesized by GAD in single neurons, was enzymatically converted to NADPH. The NADPH was amplified 10,000-350,000-fold and measured, using an enzymatic amplification reaction (NADP cycling). GAD was contained in all Purkinje cell bodies and its average activity was four- to fivefold higher than those of the molecular and granular layers of rabbit cerebellum. The GABA concentration was threefold higher in Purkinje cell bodies than in these layers. GAD activity, at a level similar to that in the cerebellar layers, was found in almost all the cell bodies of anterior horn cells from rabbit and chicken. GABA was detected in 40% of rabbit neurons and not in chicken neurons. Dorsal root ganglion cells from both species contained no measurable GAD or GABA.

Animals↗

PubMed1985

Choline acetyltransferase activities in single motor neurons from vertebrate spinal cords.

Single cell bodies of spinal motor neurons were isolated from freeze-dried sections of fresh spinal cords from six species of vertebrates. Single human neurons were also isolated from the spinal cords of three autopsy cases without neurological diseases. Choline acetyltransferase activity of these single neurons was determined by measuring acetyl-CoA formation from CoASH and acetylcholine by use of the enzymatic amplification reactions, CoA and NADP cyclings. The enzyme activity was unevenly distributed in the cytosol of spinal motor neurons of all species, but not measurable in rabbit dorsal root ganglion cells. The specific activity on a dry weight basis varied widely among the individual neurons from the species studied. The average activity was highest with rat neurons and lowest with yellowtail neurons. The neurons from cold-blooded animals (bullfrog and yellowtail) had about one-tenth the activity compared with the warm-blooded animals (cat, rabbit, rat, and hen). Human neurons, obtained under different morbid and post-mortem conditions with three autopsy cases, had very low activities corresponding to those of cold-blooded animals. Since the choline acetyltransferase activity lost from mouse brain after 11 h at 38 degrees C was 50%, the activity in human neurons was believed to actually be low in vivo.

Adult↗