Distribution of GABA‐T‐Intensive neurons in the hat forebrain and midbrain

Abstract

The neuronal distribution of gamma-aminobutyric acid (GABA) transaminase (GABA-T), the enzyme which metabolizes GABA, has been mapped in rat brain. The method involves staining for newly synthesized GABA-T by the previously established nitro blue tetrazolium technique in animals killed 8-48 hours after administration of gabaculine, an irreversible inhibitor of GABA-T. Neuronal staining is obscured by staining of other elements if initial suppression is inadequate or survival times postgabaculine are too long. With appropriate conditions, GABA-T-positive neuronal somata can be widely detected. The stained cells include neuronal groups previously reported to be GABAergic on the basis of glutamate decarboxylase (GAD)-colchicine immunocytochemistry and other methods, i.e.: Purkinje, basket, Golgi, and stellate neurons of the cerebellum; basket and stellate neurons of the hippocampus; granule and periglomerular cells of the olfactory bulb; magnocellular neurons of the hypothalamus; and neurons of the striatum, pallidum, entopeduncular nucleus, cortex, medial septal area, diagonal band, substantia innominata, reticular nucleus of the thalamus, substantia nigra, and dorsal raphe. Other cells that stain intensely for GABA-T and may be GABAergic include neurons in the midlateral septal area, accumbens, the central medial and basal nuclei of the amygdala, zona incerta, the brainstem reticular formation, central gray, interstitial nucleus of Cajal, and various thalamic nuclei including the periventricular, intralaminar, rhomboid, and subparafascicular. Known non-GABA neuronal groups are negative for GABA-T staining under these conditions, reinforcing the hypothesis that GABA neurons are far more GABA-T intensive than other neurons.

Limbic and Motor Circuitry Underlying Footshock-Induced Reinstatement of Cocaine-Seeking Behavior

“…Projections from these nuclei are primarily GABAergic and peptidergic (Nagai et al, 1983;Oertel et al, 1983;Kalivas et al, 1993b;Sun and Cassell, 1993;Zahm et al, 2001a), with the most dense projection coming from the NAshell (Zahm et al, 2001b). However, the BNSTv also sends a glutamatergic projection to the VTA (Georges and Aston-Jones, 2002).…”

A gamma‐aminobutyric‐acid‐mediated baroreceptor input to supraoptic vasopressin neurones in the rat.

“…While immunohistochemical studies indicate that GABA-containing fibres can account for its presence within the s.o.n. itself, the distribution of GABAergic cells extends forward from the perinuclear area into and beyond the diagonal band (Nagai et al 1983;Panula et al 1984). We have recently reported (Jhamandas & Renaud, 1986) that diagonal band neurones projecting to s.o.n.…”

“…had no effect on the depression in VP neuronal activity following baroreceptor activation suggested that this response was mediated by another transmitter, possibly y-aminobutyric acid (GABA). The present study was further prompted by reports of immunoreactive GABAergic neurones in the diagonal band of Broca (Nagai, McGeer & McGeer, 1983;Panula, Revuelta, Cheney, Wu & Costa, 1984). In this area, we have noted enhanced firing of s.o.n.…”

GABA-T-positive neurons in the rat supraoptic nucleus as revealed by a pharmaco-histochemical method with gabaculine.

“…They concluded that the distribution of GABA-T-intensive neurons in the rat brain was convincing evidence for the correspondence of GABA-T-intensive and GABA neurons (15,17) . Although they observed a few GABA-T-intensive neurons in the so area, they did not describe them in detail (16).…”

“…Recently, Nagai et al (17) introduced a pharmaco-histochemical method with gabaculine treatment for selectively detecting GABA-T-positive neuronal perikarya. They concluded that the distribution of GABA-T-intensive neurons in the rat brain was convincing evidence for the correspondence of GABA-T-intensive and GABA neurons (15,17) .…”