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PubMed1995

Colocalization of mu opioid receptors with GIRK1 potassium channels in the rat brain: an immunocytochemical study.

Affinity-purified anti-peptide antibodies generated against the carboxy-terminal region of the mu opioid receptor and the GIRK1 (Kir 3.1) ion channel were used to localize these two proteins in the rat brain. Mu opioid receptor immunoreactivity was detected in brain regions that were previously found to contain mu opioid binding sites using autoradiography. The distribution of GIRK1 immunoreactivity in the brain correlated well with a previous in situ hybridization study. Confocal microscopy of rat brain sections double-labelled with anti-mu opioid receptor and anti-GIRK1 antibodies revealed colocalization of GIRK1 and mu opioid receptor immunoreactivities in somata of subpopulations of neurons in the cerebral cortex, anterior olfactory nucleus, nucleus accumbens, globus pallidus, substantia nigra, peripeduncular nucleus, hippocampal formation, diagonal band, thalamus, locus coeruleus, dorsal raphe, red nucleus, nucleus of the trapezoid body, reticular nucleus, vestibular nucleus, inferior colliculus and the mesencephalic trigeminal nucleus. These anatomical findings suggest that the mu opioid receptor may couple to GIRK1 in some but not all regions of the rat brain.

Amino Acid Sequence↗
PubMedDate not supplied

Behavioral, neurochemical, anatomical and electrophysiological correlates of panic disorder: multiple transmitter interaction and neuropeptide colocalization.

Neurochemical accounts of panic disorder focus on peripheral indices of central transmitter activity, hormonal correlates and therapeutic efficacy. Anxiogenic agents augment norepinephrine activity, some anxiolytics increase serotonin neurotransmission while benzodiazepines and antidepressants influence catecholamine, indoleamine and gamma-aminobutyric acid turnover in infrahuman subjects. Reliable correlates of central transmitter activity in panic disorder are not in evidence. While animal models of anxiety may not mirror the symptom profile of panic, neurobiological accounts of panic disorder fail to consider extensive central colocalization of neurotransmitter and putative neurotransmitters. In effect, transmitter release in major ascending and descending transmitter systems is modulated by variable neuropeptide interfacing. The behavioral concomitants of psychological disturbance likely follow from variable neurochemical release induced by stimuli as well as conditioning and sensitization. The functional role of receptor sites associated with multiple neurochemical systems may vary and the sensitivity and/or density of receptor sites may be modified. Accordingly, the behavioral and neurochemical concomitants of acute and chronic pathology may be fundamentally different from one another. The present review argues that the symptoms of panic disorder and the etiology of the illness must be evaluated against a background of genetic, organismic and experiential factors. Such variables presumably underlie the diverse behavioral symptoms associated with panic disorder and variations in the therapeutic efficacy of pharmacological treatment.

Animals↗
PubMed1997

The Src family kinases, Fgr, Fyn, Lck, and Lyn, colocalize with coated membranes in platelets.

Nonreceptor protein tyrosine kinases phosphorylate proteins, thereby activating many intracellular signaling pathways and mediating protein-protein interactions. Protein phosphorylation is regulated in large part by the subcellular localization of these kinases and their respective substrates. Src is the most studied of these kinases, although other members of the Src family have been shown to be important in the differentiation of specific cell types. Src and Src family members are reported to be membrane-associated, but detergent-extraction studies have demonstrated a major difference in the solubility of Src compared with other members of the Src family (Fgr, Fyn, Lck, Lyn, and Yes), suggesting that their subcellular distributions may be different. By immunoelectron microscopy, we demonstrate that, unlike Src, the Src-related kinases are associated with electron-dense cytoplasmic domains and plasma membrane domains that correspond in size and frequency to endocytotic vesicles and coated pits. Clusters of labeling for these kinases also were seen adjacent to granule membranes. These kinases colocalize with the coated vesicle protein, clathrin, confirming their association with this class of endocytotic vesicle. We hypothesize that this vesicular association of Src-related kinases indicates a role for them in the endocytotic vesicle-mediated uptake and trafficking of plasma proteins into platelet granules.

Animals↗
PubMed1997

Colocalization of stomatin (band 7.2b) and actin microfilaments in UAC epithelial cells.

Cytolocalization of stomatin, an integral membrane protein also called erythrocyte band 7.2b, was investigated in a human epithelial cell line in which the expression of this protein is up-regulated after treatment with interleukin-6 and dexamethasone. A monoclonal antibody against stomatin was used to perform immunofluorescence and immunoelectron microscopy. The data show that stomatin concentrates preferentially in small plasma membrane protrusions. It is also found in abundance in a juxtanuclear structure possibly derived from the Golgi apparatus. Fluorescent double staining using the anti-stomatin antibody and the actin binding drug phalloidin shows a significant degree of colocalization of stomatin and cortical actin microfilaments. This association remains after actin filament disruption disruption by cytochalasin D treatment indicating a strong connection between stomatin and the membrane-associated cytoskeleton.

Actins↗
PubMed1998

Colocalization of nitric oxide synthase and some neurotransmitters in the intramural ganglia of the guinea pig urinary bladder.

The distribution of nitrergic neurons was investigated by using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and nitric oxide synthase (NOS) immunohistochemistry in wholemount preparations of the urinary bladder in guinea pigs. Both NADPH-d+ and NOS+ neurons were located predominantly in the bladder base. Double staining showed that 70.9% of the NADPH-d+ neurons coexpressed NOS. Acetylcholinesterase histochemistry revealed that a majority of the intramural neurons were reactive, and about half of them (51.4%) were double labelled for NOS. Tyrosine hydroxylase-positive neurons were also distributed mainly in the bladder base but in a neuronal population that was separate from the preponderant NADPH-d+ neurons. Vasoactive intestinal polypeptide immunoreactivity was also detected in the some of intramural ganglion cells, in which 21.3% of them coexpressed NADPH-d. Calcitonin gene-related peptide and substance P immunoreactivities were confined to nerve fibers, often in close association with NADPH-d+ cells or extended along the blood vessels. These results have demonstrated the colocalization of NADPH-d and NOS in the majority of intramural ganglion cells. Many of the nitrergic neurons are apparently cholinergic, indicating that they are parasympathetic postganglionic neurons, and this underscores NO as the major neuromodulator in the parasympathetic nerves in the bladder walls. The localization of vasoactive intestinal polypeptide in nitrergic neurons suggests that the peptide may complement NO for regulation of micturition reflex. The close relationship of NADPH-d-reactive intramural neurons with calcitonin gene-related peptide and substance P fibers, most probably derived from dorsal root ganglion cells, suggests that NO released from the local neurons may exert its influence on the sensory neural pathways in the urinary bladder.

Acetylcholinesterase↗
PubMed1998

Interaction of p59fyn kinase with the dynein light chain, Tctex-1, and colocalization during cytokinesis.

The protein tyrosine kinase p59fyn (Fyn) plays important roles in both lymphocyte Ag receptor signaling and cytokinesis of proB cells. We utilized yeast two-hybrid cloning to identify the product of the tctex-1 gene as a protein that specifically interacts with Fyn, but not with other Src family kinases. Tctex-1 was recently identified as a component of the dynein cytoskeletal motor complex. The capacity of a Tctex-1-glutathione S-transferase fusion protein to effectively bind Fyn from cell lysates confirmed the authenticity of this interaction. Tctex-1 binding required the first 19 amino acids of Fyn and integrity of two lysine residues within this sequence that were previously shown to be important for Fyn interactions with the immunoreceptor tyrosine-based activation motifs (ITAMs) of lymphocyte Ag receptors. Expression of tctex-1 mRNA and protein was observed in all lymphoma lines analyzed, and immunofluorescence confocal microscopy localized the protein to the perinuclear region. Analysis of a T cell hybridoma revealed prominent colocalization of Tctex-1 and Fyn at the cleavage furrow and mitotic spindles in cells undergoing cytokinesis. Our results provide a unique insight into a mechanism by which Tctex-1 might mediate specific recruitment of Fyn to the dynein complex in lymphocytes, which may be a critical event in mediating the previously defined role of Fyn in cytokinesis.

Animals↗
PubMed1998

Colocalization of single ribosomes with intermediate filaments in puromycin-treated and serum-starved mouse embryo fibroblasts.

Previous experiments have revealed a relatively weak electrostatic binding capacity of in vitro reconstituted intermediate filaments (IFs) as well as of natural IFs of whole cell mount preparations for purified ribosomal particles of mammalian origin. In order to demonstrate that such associations also occur in vivo, intact cells were subjected to double immunofluorescence microscopy using antibodies directed against vimentin and ribosomal protein S17. Since in proliferating cells the majority of the ribosomal particles are assembled into polyribosomes and these are to a great extent associated with microfilaments, in vitro cultured mouse embryo skin fibroblasts (MSF cells) were treated with puromycin to allow the formation of single ribosomes. Employing confocal laser scanning microscopy, the ribosomes were detected in colocalization with vimentin IFs. Disassembly of polyribosomes was also achieved by serum starvation of cultured cells. In this case, MSF cells of a low passage attained an extended and flattened appearance with the vimentin IFs being directly associated with the cell nuclei, radiating into the peripheral areas of the cells or showing a stress fiber-like distribution. In both cases, considerable quantities of ribosomal material were seen in close neighborhood to vimentin IFs. Frequently, these ribosome-IF associations were coaligned with microtubules and they also surrounded myosin I-decorated stress fibers. Double labeling with the vital, RNA-specific fluorochrome SYTO 14 produced a fluorescence pattern largely superimposable on that of ribosomal protein S17. Treatment of the starved cells with either demecolcine or cytochalasin D had an only moderately disturbing effect on vimentin IF distribution and the ribosomes stayed in contact with the vimentin IFs. On the basis of these results, it is conceivable that IFs play a role in the storage of ribonucleoprotein particles in general and non-translating ribosomes in particular in the cytoplasm of animal cells. In addition, the often seen coalignment of IFs with microtubules and microfilaments might serve facilitated and directional transport of ribonucleoprotein particles from the nucleus to peripheral areas of the cell.

Actin Cytoskeleton↗
PubMed1997

Selective colocalization of immunoreactivity for intracellular gonadal hormone receptors and tyrosine hydroxylase in the ventral tegmental area, substantia nigra, and retrorubral fields in the rat.

Gonadal hormones influence brain functions, including motor and motivational behaviors, transmitter release, and receptor binding in midbrain dopamine systems. Much of this influence suggests genomic hormone action. To identify which midbrain cells may be targets of genomic influence, double label immunocytochemistry was used to map intracellular estrogen and androgen receptors and tyrosine hydroxylase (TH) in the ventral tegmental area (VTA), substantia nigra (SN), and retrorubral fields (RRF) in intact, adult rats. The distribution of estrogen and androgen receptor immunoreactivity was highly selective, similar in males and females, and largely nonoverlapping. Estrogen receptors were present within subpopulations of cells in the ventrolateral paranigral VTA and rostrolateral RRF; of these, only a few cells in the RRF were immunoreactive for TH. Cells immunoreactive for androgen receptors were numerous in the paranigral and parabrachial VTA, SN pars lateralis and dorsomedial pars compacta, and lateral RRF. Nearly every androgen receptor-bearing cell in the VTA and SN pars compacta, roughly half in the SN pars lateralis, and about one-third in the RRF were TH immunopositive. The localization of estrogen receptors approximates the distribution of subsets of cells labeled following neostriatal injections, whereas androgen receptors tend to occupy regions labeled by injections in cortical or limbic targets. These receptor-specific alignments with origins of nigrostriatal, mesolimbic, and mesocortical projections are consistent with identified estrogen influence over motor behaviors and androgen involvement in motivational functions and may hold clues for understanding hormone action in these and other functions and dysfunctions of midbrain dopamine systems.

Animals↗
PubMed1999

Nitric oxide synthase in the guinea pig preoptic area and hypothalamus: distribution, effect of estrogen, and colocalization with progesterone receptor.

Nitric oxide (NO) may function as an intercellular messenger in the hypothalamus and may play a role in the control of gonadotropin-releasing hormone (GnRH) secretion and sexual behavior. Progesterone also plays an important role in the regulation of reproductive functions. Recent experiments have shown that progesterone-induced sexual behavior in ovariectomized, estrogen-primed rats was caused by the release of NO from nitric oxide synthase (NOS)-containing neurons and the subsequent stimulation of the release of GnRH. To provide further neuroanatomical support for the role of NO in these gonadal steroid-dependent behavioral and physiological processes, we determined (1) the distribution of the nicotinamide-adenosine-dinucleotide phosphate-diaphorase (NADPHd) and NOS enzymes in the guinea pig preoptic area and hypothalamus, regions that contain steroid receptors; (2) the effect of estrogen on NADPHd activity in these regions; and (3) the neuroanatomical relationship between NOS and the progesterone receptor (PR). For this purpose, single-(NADPHd) and double- (NADPHd with NOS or NADPHd with PR or NOS with PR) staining techniques were applied to sections of brains of guinea pigs. The studies showed scattered NADPHd-positive neurons in most parts of the preoptic area and heavily stained cells in the hypothalamus. In these regions, the pattern and density of NOS immunoreactivity closely corresponded to the pattern of NADPHd staining. Quantitative analysis showed an increase in the number of NADPHd-positive neurons in the ventrolateral nucleus of ovariectomized animals primed with estradiol. Approximately 16% of the NOS-immunoreactive (IR) cells in the rostral preoptic area and 55% of NOS-IR cells in the ventrolateral nucleus displayed PR immunoreactivity. These results suggest that NOS may be regulated by gonadal steroids and provide neuroanatomical evidence that progesterone may exert its effect directly on more than half of NOS-synthesizing cells in the ventrolateral nucleus, a key region in the control of sexual behavior.

Animals↗
PubMed1999

CART peptide-immunoreactive neurones in the nucleus accumbens in monkeys: ultrastructural analysis, colocalization studies, and synaptic interactions with dopaminergic afferents.

Cocaine- and amphetamine-regulated transcript (CART) is a novel mRNA whose level of expression was found to be increased in the striatum after acute administration of psychomotor stimulants in rats. To define better the potential role of CART peptides in behavioural and physiologic changes induced by psychomotor stimulants, we analyzed the distribution, ultrastructural features, synaptic connectivity, and transmitter content of CART peptide-immunoreactive neurones in the nucleus accumbens in monkeys. Medium-sized CART peptide-immunoreactive neurones within a rich plexus of labelled varicosities were found mostly in the medial division of the shell of the nucleus accumbens in monkeys. At the electron microscope level, CART peptide immunoreactivity was exclusively associated with neuronal structures that included perikarya, dendrites, spines as well as nerve terminals packed with electron-lucent and dense-core vesicles. Most CART peptide-containing somata displayed the ultrastructural features of striatal output neurones. The majority of labelled terminals formed symmetric axodendritic synapses and displayed gamma-aminobutyric acid (GABA) immunoreactivity. CART peptide-immunoreactive somata were not immunoreactive for parvalbumin and somatostatin, two markers of striatal interneurones, nor for calbindin D-28k, a marker of a subpopulation of projection neurones. In double-immunostained sections, CART peptide-immunoreactive dendrites were found to be contacted by tyrosine hydroxylase-positive terminals which displayed the ultrastructural features of dopamine-containing boutons. These findings strongly suggest that CART peptides may be a cotransmitter with GABA in a subpopulation of projection neurones in the monkey accumbens. Furthermore, the fact that CART peptide-immunoreactive neurones receive direct synaptic inputs from dopaminergic afferents and are particularly abundant in the caudomedial division of the shell of the nucleus accumbens suggest that CART peptides might be involved in neuronal and behavioural changes that underlie addiction to psychomotor stimulants and feeding in primates.

Animals↗
PubMed1999

Immunocytochemistry of GABA in the central complex of the locust Schistocerca gregaria: identification of immunoreactive neurons and colocalization with neuropeptides.

The central complex is a highly organized neuropil structure in the insect brain and plays a role in motor control and visual orientation. We describe the distribution of gamma-aminobutyric acid (GABA) immunostaining in the central complex of the locust Schistocerca gregaria in an effort to analyze inhibitory neural circuits within this brain area. Antisera against GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase resulted in identical patterns of immunostaining. Cell counts revealed about 100 bilateral pairs of GABA-immunoreactive neurons with arborizations in the central complex. Five types of immunostained neurons could be identified through reconstruction of the staining pattern, comparison with individually stained neurons, and double labeling experiments with Neurobiotin-injected neurons. All of these GABA-immunostained neurons are tangential neurons that connect the lateral accessory lobes to distinct layers of the central body. Three types of immunostained neurons (TL2, TL3, TL4) invade the lower division of the central body, and two additional types of neurons (TU1, TU2) have ramifications in layers I and II of the upper division of the central body. Double-labeling experiments with peptide antisera suggest that peptides related to Phe-Met-Arg-Phe-NH2/bovine pancreatic polypeptide and Dip-allatostatin might act as cotransmitters with GABA in TL4 neurons of the lower division and (Dip-allatostatin only) in TU2 neurons of the upper division of the central body. The high conservation in the pattern of GABA immunostaining in all insect species investigated so far suggests that GABA plays an essential role in the basic neural circuitry of the central complex in insects.

Animals↗
PubMed1999

Mu-opioid and NMDA-type glutamate receptors are often colocalized in spiny neurons within patches of the caudate-putamen nucleus.

The patch compartments of the caudate-putamen nucleus (CPN) are enriched in mu-opioid receptors (MORs) and have been recently implicated in reward-related behaviors. This function has been established more clearly in the nucleus accumbens, where physiological and anatomical studies show reward-associated interactions involving MORs and N-methyl-D-aspartate-type glutamate receptors (NMDARs). We examined the immunolabeling for MOR and NMDAR subunit NR1 in patches of the rat CPN to determine the potential relevance of dual activation of the respective receptors. Electron microscopy showed the presence of MOR and/or NR1 immunoreactivity (IR) in many perikarya, dendrites, and spines and in morphologically heterogeneous axon terminals. In each 1,000-microm(2) area, the dually labeled dendrites and spines constituted 65% (37/57) and 37% (9/25) of the total NR1-labeled and 34% (37/109) and 13% (9/71) of the total MOR-labeled dendritic profiles. Dually labeled spines received asymmetric excitatory-type synapses from terminals, which were generally unlabeled, but also occasionally contained MOR and/or NR1. The asymmetric synapses comprised the majority (81%) of the total 263 synaptic contacts between MOR- and NR1-labeled neuronal profiles. In dendrites and spines, MOR-IR was localized mainly along nonsynaptic plasma membranes, whereas NR1-IR was more often associated with asymmetric postsynaptic densities and cytoplasmic organelles. In contrast to dendrites, 6% (1.3/22) of NR1-IR and 4% (1.3/33) of MOR-IR axon terminals were dually labeled in each 1,000-microm(2) area. Most singly or dually labeled terminals formed asymmetric synapses with MOR- or NR1-labeled spines. Our results suggest that opioids acting through MOR and excitatory neurotransmitters through NMDAR dually regulate the output of single spiny neurons and some of their excitatory afferents in the CPN.

Animals↗
PubMed2000

Colocalization of choline acetyltransferase and gamma-aminobutyric acid in the developing and adult turtle retinas.

Acetylcholine and gamma -aminobutyric acid (GABA) are putative neurotransmitters in the adult vertebrate retina. In this study, cells that coexpress choline acetyltransferase (ChAT) and GABA or glutamic acid decarboxylase (GAD) were investigated in turtle retinas from stage 14 (S14) to adulthood by using a double-labeling immunofluorescence technique. ChAT immunoreactivity was observed at S15 and included not only the presumptive starburst cholinergic amacrine cells but also a population in the ganglion cell layer (GCL) that expressed ChAT transiently during the embryonic stages (see the accompanying paper: Nguyen et al. [2000] J. Comp. Neurol. 420:512-526).

Aging↗
PubMed2000

N-methyl-D-aspartate (NMDA) receptors in the ventral tegmental area: subcellular distribution and colocalization with 5-hydroxytryptamine(2A) receptors.

Glutamate receptors of the N-methyl-D-aspartate (NMDA) subtype have been implicated in behavioral sensitization to psychostimulants and in psychotic behaviors involving excitation of ventral tegmental area (VTA) dopaminergic neurons. Antagonists of serotonin (5-hydroxytryptamine, 5-HT) receptors of the 5-HT(2A) subtype are potent antipsychotics that attenuate these NMDA-evoked responses. We examined the electron microscopic immunocytochemical localization of antisera against the NMDA R1 subunit (NMDAR1) and 5-HT(2A) receptors to determine potential sites for their dual activation in the rat paranigral and parabrachial VTA subdivisions that are distinguished, in part, by their respective striatolimbic and cortical projections. In both regions, NMDAR1 immunoreactivity was localized mainly to the cytoplasm of somata and dendrites, and was only occasionally seen near or within excitatory-type asymmetric synapses. Many of the NMDAR1-labeled somata and dendrites also expressed 5-HT(2A) receptors, having a similar, but largely non-overlapping, neuronal distribution. The mean area density of NMDAR1 and dually labeled dendritic profiles was significantly greater in the paranigral than in the parabrachial VTA. NMDAR1 was also present in small axons showing a similar regional difference in area density. No regional difference in area density was seen in dendrites or small axons containing only 5-HT(2A) receptors. Our results indicate that NMDA and 5-HT(2A) receptors in the VTA are transiently expressed on synaptic plasma membranes of single neurons showing widespread cytoplasmic distributions of each of the receptors. They also suggest a major role for NMDA receptors in modulating the output of paranigral neurons and the release of transmitters from axons passing through this region.

Animals↗
PubMed1998

DNA loop anchorage region colocalizes with the replication origin located downstream to the human gene encoding lamin B2.

The recently developed procedure of topoisomerase II-mediated DNA loop excision has been used to analyze the topological organization of a human genome fragment containing the gene encoding lamin B2 and the ppv1 gene. A 3.5 kb long DNA loop anchorage/topoisomerase II cleavage region was found within the area under study. This region includes the end of the lamin B2 coding unit and an intergenic region where an origin of DNA replication was previously found. These observations further corroborate the hypothesis that DNA replication origins are located at or close to DNA loop anchorage regions.

Binding Sites↗
PubMed1999

Differential behavior of E-cadherin and occludin in their colocalization with ZO-1 during the establishment of epithelial cell polarity.

At the initial stage of cell-cell contact of epithelial cells, primordial spot-like junctions are formed at the tips of thin cellular protrusions radiating from adjacent cells, where E-cadherin and ZO-1 are precisely coconcentrated (Yonemura et al., 1995, J. Cell Sci. 108:127-142). In fully polarized epithelial cells, E-cadherin and ZO-1 are completely sorted into belt-like adherens junctions (AJ) and tight junctions (TJ), respectively. Here we examined the behavior of occludin, an integral membrane protein consisting of TJ, during the establishment of epithelial cell polarity. Using confocal immunofluorescence microscopy, we quantitatively compared the spatial relationship of occludin/ZO-1 with that of E-cadherin/ZO-1 during epithelial cellular polarization by replating or wounding cultured mouse epithelial cells (MTD1-A). At the initial stage of cell-cell contact, E-cadherin and ZO-1 appeared to be simultaneously recruited to the primordial form of spot-like junctions at the tips of cellular processes which showed no concentration of occludin. Then, as cellular polarization proceeded, occludin was gradually accumulated at the ZO-1-positive spot-like junctions to form belt-like TJ, and in a complementary manner E-cadherin was sorted out from the ZO-1-positive spot-like junctions to form belt-like AJ. The molecular mechanism of TJ/AJ formation during epithelial cellular polarization is discussed with special reference to the roles of ZO-1.

Animals↗
PubMed2000

Sparse colocalization of somatostatin- and GABA-immunoreactivity in the entorhinal cortex of the rat.

We studied the regional and laminar distribution of neurons expressing immunoreactivity with antibodies against the neuropeptide somatostatin (SOM) in the entorhinal cortex of colchicine-treated rats. We further determined whether these neurons also express immunoreactivity with antibodies against the neurotransmitter gamma-aminobutyric acid (GABA). Frontally and horizontally cut brain sections were subjected to double immunofluorescence histochemistry and investigated in a two-laser confocal laser scanning fluorescence microscope. The exact position of each single- or double-labeled cell was obtained via the preparation of large-scale digital fluorescence images superimposed on a brightfield digital image obtained postscanning after decoverslipping and staining with cresyl violet. Three types of SOM-positive cells were found: big multipolar cells (10-15% of the SOM-positive cells), oval cells (15-20%), and small spherical cells (majority of SOM-positive cells). Most cells were seen in layer III. In addition, we found immunoreactive cells in the other layers, with the fewest cells in layers I and IV (lamina dissecans). Of the SOM-positive cells, 18% also expressed GABA immunoreactivity; of the GABA-positive cells, 8% were also immunoreactive for SOM. Double-labeled cells were mostly small spherical cells and, infrequently, multipolar. These data indicate that in the entorhinal cortex, a large proportion of the cells belonging to the SOM population do not express GABA. We speculate that there may be several subpopulations of SOM cells, of which the largest may consist of non-GABAergic, excitatory interneurons.

Animals↗