Molecular and Physiological Diversity of Cortical Nonpyramidal Cells

Abstract

The physiological and molecular features of nonpyramidal cells were investigated in acute slices of sensory-motor cortex using whole-cell recordings combined with single-cell RT-PCR to detect simultaneously the mRNAs of three calcium binding proteins (calbindin D28k, parvalbumin, and calretinin) and four neuropeptides (neuropeptide Y, vasoactive intestinal polypeptide, somatostatin, and cholecystokinin). In the 97 neurons analyzed, all expressed mRNAs of at least one calcium binding protein, and the majority (n ϭ 73) contained mRNAs of at least one neuropeptide. Three groups of nonpyramidal cells were defined according to their firing pattern. (1) Fast spiking cells (n ϭ 34) displayed tonic discharges of fast action potentials with no accommodation. They expressed parvalbumin (n ϭ 30) and/or calbindin (n ϭ 19) mRNAs, and half of them also contained transcripts of at least one of the four neuropeptides. (2) Regular spiking nonpyramidal cells (n ϭ 48) displayed a firing behavior characterized by a marked accommodation and presented a large diversity of expression patterns of the seven biochemical markers. (3) Finally, a small population of vertically oriented bipolar cells, termed irregular spiking cells (n ϭ 15), fired bursts of action potentials at an irregular frequency. They consistently co-expressed calretinin and vasoactive intestinal polypeptide. Additional investigations of these cells showed that they also co-expressed glutamic acid decarboxylase and choline acetyl transferase. Our results indicate that neocortical nonpyramidal neurons display a large diversity in their firing properties and biochemical patterns of co-expression and that both characteristics could be correlated to define discrete subpopulations.

Extracellular Matrix Plasticity and GABAergic Inhibition of Prefrontal Cortex Pyramidal Cells Facilitates Relapse to Heroin Seeking

“…PV-expressing neurons are fast-spiking inhibitory interneurons (Cauli et al, 1997;Kawaguchi and Kondo, 2002). Therefore, adaptation of ECM molecules may lead to an alteration in the structural stability or physiological properties of synapses at fastspiking GABAergic interneurons.…”

GABAergic Neurons Immunoreactive for Calcium Binding Proteins are Reduced in the Prefrontal Cortex in Major Depression

“…These cells differ by morphology, type of contacts with pyramidal neurons, pattern of firing, and monoaminergic innervation. PV-IR interneurons correspond to basket or chandelier cells, make contacts on somata and axonal initial segments of pyramidal neurons and regulate cortical output activity (Baimbridge et al, 1992;Cauli et al, 1997;Conde et al, 1994;Cruz et al, 2003;DeFelipe, 1989DeFelipe, , 1997Gabbott et al, 1997;Lewis and Lund, 1990;Lund and Lewis, 1993;Somogyi et al, 1998). PV-IR neurons have physiological properties characteristic of fast-spiking interneurons Kubota, 1993, 1997;Zaitsev et al, 2005).…”

“…PV-IR neurons have physiological properties characteristic of fast-spiking interneurons Kubota, 1993, 1997;Zaitsev et al, 2005). In contrast, CB-IR interneurons have a double bouquet morphology, form characteristic dense axonal collaterals in layer I, make synapses on the dendrites and dendritic spines of pyramidal neurons, and have physiological features consistent with nonfast spiking interneurons (Cauli et al, 1997;DeFelipe, 1997;Gabbott et al, 1997;Kubota, 1993, 1997;Lund and Lewis, 1993;Zaitsev et al, 2005). In addition, CB and PV cortical neurons differ by specific serotoninergic and dopaminergic innervation (Freund et al, 1990;Hornung, 2003;Hornung and Celio, 1992;Sesack et al, 1995).…”

Physiological and Molecular Characteristics of Rat Hypothalamic Ventromedial Nucleus Glucosensing Neurons

“…Some mRNA species were present in very low abundance and required the use of additional steps for detection. For these, a second round of amplification was carried out with nested primers by multiplex PCR (mPCR) using the first-round PCR products as a template (Table 2) and a shorter extension time (51). The second-round reaction contained 1 l of first-round PCR product as a template.…”