Parvalbumin immunoreactivity in the thalamus of guinea pig: Light and electron microscopic correlation with gamma-aminobutyric acid immunoreactivity

1994 ◽  
Vol 348 (4) ◽  
pp. 556-569 ◽  
Author(s):  
S. de Biasi ◽  
P. Arcelli ◽  
R. Spreafico
1985 ◽  
Vol 33 (3) ◽  
pp. 249-257 ◽  
Author(s):  
P Somogyi ◽  
A J Hodgson

Two methods are described for the immunocytochemical demonstration of immunoreactive gamma-aminobutyric acid (GABA) in the visual cortex of the cat, an area that contains several types of GABAergic neurons and requires combined methods for their characterization. The first method is illustrated by a representative example of a Golgi-impregnated and gold-toned interneuron of the "bitufted" type situated in layer VI and having an ascending axon. After recording the three-dimensional features of the cell, semithin (0.5 micron) sections of the perikaryon were cut and GABA was demonstrated in the cell body by the unlabeled antibody enzyme method. While immunocytochemistry was used to determine the probable transmitter of the neuron, Golgi-impregnation of the same cell was used to identify its neuronal type. Since aldehyde-osmium fixation was used, further electron microscopic (EM) analysis of the neuron's synaptic connections was possible. The second procedure demonstrated GABA in EM sections of aldehyde-osmium-fixed cortex using protein A-gold as an immunocytochemical marker. Immunoreactivity was found in certain neurons, dendrites, axons, and boutons forming type II synaptic contacts that from previous studies have been thought to be GABAergic. Thus ultrastructural analysis using optimal conditions can now be supplemented with the identification of the transmitter in the same section.


1995 ◽  
Vol 7 (5) ◽  
pp. 1339 ◽  
Author(s):  
MC Catlin ◽  
DH Penning ◽  
JF Brien

The objective of this study was to determine the effects of acute direct exposure to ethanol, hypoxia or ethanol plus hypoxia on K+-stimulated gamma-aminobutyric acid (GABA) efflux (neuronal release minus uptake) in the hippocampus of the near-term fetal and adult guinea-pig. Transverse hippocampal slices were studied in a static-interface system. Exposure in vitro to ethanol or hypoxia involved 10-min incubation with 50 mM ethanol or 10-min incubation in a 95% N2/5% CO2 environment. GABA was quantitated by HPLC. Ethanol did not alter K+-stimulated GABA efflux; hypoxia augmented K+-stimulated GABA efflux three-fold in the near-term fetus and seven-fold in the adult; concurrent exposure to ethanol did not alter the effect of hypoxia. The data demonstrate that, for acute direct exposure to hypoxia and/or ethanol, only hypoxia increases K+-stimulated GABA efflux, the magnitude of which is dependent on the extent of development of the GABA system.


1985 ◽  
Vol 249 (2) ◽  
pp. G192-G196 ◽  
Author(s):  
N. Saito ◽  
K. Taniyama ◽  
C. Tanaka

The presence of gamma-aminobutyric acid (GABA)-ergic neuron in guinea pig gallbladder was investigated by measuring GABA contents and glutamate decarboxylase (GAD) activity and by demonstrating the uptake and release of [3H]GABA. GABA and GAD are both present in the gallbladder, and a positive correlation in regional distribution was observed among GABA, GAD, and the number of ganglion cells. The uptake of [3H]GABA by the gallbladder showed two saturable components; a high-affinity component (Km = 23.3 microM, Vmax = 7.63 nmol X g-1 X 10 min-1) and a low-affinity component (Km = 515 microM, Vmax = 57.1 nmol X g-1 X 10 min-1). These high-affinity and low-affinity transport systems corresponded to those obtained in the presence of beta-alanine and L-2,4-diaminobutyric acid, respectively, thereby suggesting the presence of neuronal and nonneuronal GABA transport systems in this tissue. Electrical transmural stimulation produced an increase in [3H]-GABA release from the isolated gallbladder preloaded with [3H]GABA, in the presence of beta-alanine. The stimulation-evoked release of [3H]GABA was prevented by calcium-free medium containing 1 mM EGTA and tetrodotoxin, thereby indicating that the released GABA originates from the nerve terminals. These results provide evidence for the presence of GABA-ergic neurons in the guinea pig gallbladder.


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