Distribution of GABA^Areceptor alpha 1 subunit‐like immunoreactivity in comparision with that of enkephalin and substance P in the rat forebrain

Abstract

The gamma-aminobutyric acid-A receptor consists of several subunits. In this immunohistochemical study we investigated the regional distribution of the alpha 1 subunit with an antibody directed against a specific amino acid sequence (1-9) of the (1-9) of the alpha 1 subunit. We compared the distribution pattern of the alpha 1 subunit-like immunoreactivity with that of substance P- and enkephalin-like immunoreactivities in adjacent sections of the rat forebrain. alpha 1 subunit-like immunoreactivity appeared in the form of varicosities and fibers. A band-like terminal staining pattern (woolly fibers) that has been shown by others for substance P- and enkephalin-like immunoreactivity is also observed for alpha 1 subunit-like immunoreactivity. In contrast to substance P and enkephalin, numerous alpha 1 subunit-like immunoreactive perikarya were found. The highest density of alpha 1 subunit-like immunoreactive fibers and perikarya was found in the pallidal areas and the substantia nigra pars reticulata whereas the nucleus accumbens and the caudate putamen displayed a low density. alpha 1 subunit-like immunoreactive neurons resembled typical pallidal neurons. Some of these neurons were pericellularly stained with enkephalin-like immunoreactive varicosities in the dorsal pallidum. The distribution pattern of alpha 1 subunit-like immunoreactivity reflects a partial overlap with the substance P and enkephalin system although a differential distribution to each of these peptides was observed for cell bodies, fibers, and axon terminals.

Distribution of the major γ‐aminobutyric acidA receptor subunits in the basal ganglia and associated limbic brain areas of the adult rat

“…It is probable that subunit ␣1-and ␤2-IR are located on the same types of local circuit neurons, which were previously characterized by subunit ␣1-IR (Marksteiner et al, 1995;Caruncho et al, 1996a;Waldvogel et al, 1997). Although we failed to label somata with our ␥2 antibody, the subunit ␥2-ir dendrites presumably belong to the same cell type.…”

“…Most conspicuous were darkly stained processes of up to 4 m diameter in the ventral n. accumbens (Fig. 5g, for subunit ␣1), presumably associated with woolly fibers (Haber and Nauta, 1983;Marksteiner et al, 1995). Single immunoreactive spines were observed along these less branched and up to 500-m-long processes (Fig.…”

“…6e,f). In addition, several moderately subunit ␣1-, ␤2-, and ␥1-ir, straight processes with a diameter of up to 4 m, presumably associated with woolly fibers (Haber and Nauta, 1983;Marksteiner et al, 1995), were sometimes followed for more than 150 m in sagittal sections (compare n. accumbens, Fig. 5g).…”

Contributions of Developmental Studies in the Dogfish <b><i>Scyliorhinus canicula</i></b> to the Brain Anatomy of Elasmobranchs: Insights on the Basal Ganglia

“…1 o-r, x). In addition to the especially high density of GAD-ir terminals surrounding immunonegative somata and dendrites of the area superficialis basalis cells, structures similar to the 'woolly fibers' described in pallidal nuclei of mammals and birds [Ribak et al, 1979;Marksteiner et al, 1995;Reiner et al, 2004] were also noted ( fig. 1 x; 2 c).…”

Striatal efferents preferentially innervate neurons in the ventral pallidum containing GABAA receptor ? 1 subunit-like immunoreactivity

“…Free-floating sections (60 pm) were processed as previously described (Marksteiner et al, 1992(Marksteiner et al, ,1995. After incubation with 10% normal goat serum (Dakopatts, Copenhagen, Denmark), sections were incubated with primary antiserum (anti-al, 1:750; anti-aZ, 1:750; anti-SP, 1:1,000).…”