Selective staining of a subset of GABAergic neurons in cat visual cortex by monoclonal antibody VC1.1

Abstract

VC1.1 is a monoclonal antibody generated against cat area 17, which selectively outlines subsets of cortical neurons (Arimatsu et al., 1987). This study was conducted to determine the ultrastructural distribution of the VC1.1 antigen and to identify the particular subclasses of cortical neurons that were labeled. In the light microscope, VC1.1 delineated the surfaces of neurons located mainly in layer IV but also in other layers. The staining surrounded neuronal cell bodies and dendrites in a periodic or meshwork pattern but did not label axons. VC1.1-labeled neurons were morphologically heterogeneous and included multipolar, bipolar, and bitufted classes. In the electron microscope, VC1.1 immunoreactivity surrounded presynaptic membranes of terminal boutons and intersynaptic sections of postsynaptic membranes, but was not present within terminal boutons or synaptic clefts. Both asymmetric and symmetric synapses were immunoreactive. Labeling was also observed intracellularly on VC1.1-outlined neurons, associated with perisynaptic portions of plasma membranes. Tract-tracing methods were used in conjunction with immunocytochemistry to determine whether VC1.1 identified projection neurons, local circuit neurons, or a combination of both types. Layer V and VI corticogeniculate and corticotectal projection neurons were retrogradely labeled with rhodamine fluorescent latex microspheres. In a large sample of retrogradely labeled neurons, none were VC1.1-positive, suggesting that VC1.1 stained a population of local circuit neurons. Additional immunocytochemical double-labeling studies with an antiserum to GABA and VC1.1, revealed that VC1.1-positive neurons were immunoreactive to GABA. These were a major subset of the GABAergic neurons in area 17 and tended to have medium to large cell bodies. It is concluded that VC1.1 identifies a new, immunologically distinct subset of GABAergic neurons in area 17. The restricted distribution of this antigen on perisynaptic portions of GABA-containing cells and surrounding terminal boutons onto these cells suggests that this antigen may play an important role in inhibitory cortical circuits.

STEP61: A Member of a Family of Brain-Enriched PTPs Is Localized to the Endoplasmic Reticulum

“…Deeply anesthetized Long Evans rats were perfused with 0.1 M sodium phosphate buffer, pH 7.4, containing 0.1 U/ml sodium heparin, followed by perfusion with ϳ250 ml of a fixative containing 4% paraformaldehyde and 0.2% glutaraldehyde in 0.1 M phosphate buffer, pH 7.4. The brains were left in the skull for 2 hr at 4ЊC, removed, blocked, and post-fixed in the perfusion solution for 4 hr (Naegele et al, 1988). Vibratome sections (100 m thick) were cut in coronal plane and collected in cold 0.1 M phosphate buffer.…”

Differentiation of glycoconjugates localized to sensory terminals and selected sites in brain

“…The contribution of Glc A3-S04 in cortical cells, for example, is known little beyond implications from comparative data showing their content of the calcium-binding protein parvalbumen (Kosaka et al, 1990) and of glutamic acid decarboxylase indicative of neuroinhibition (Naegele et al, 1988;Naegele and Barnstable, 1989). Localizing a substance of unknown significance at a site of specialized physiological activity allows for speculation concerning the constituent's functional contribution.…”

Cell surface molecules containing N-acetylgalactosamine are associated with basket cells and neurogliaform cells in cat visual cortex

“…Previous studies had demonstrated that GABAergic neurons with either bitufted or multipolar dendrites were stained preferentially by monoclonal antibodies VC 1.1 and VC5.1 or the lectin VVA (Naegele et al, 1988;Mulligan et al, 1989). These findings suggested that each marker identified more than one fundamental cell type.…”

“…There is now evidence that certain plant lectins and monoclonal antibodies identify subsets of cortical local circuit neurons. Lectins from Viciu villosa (VVA) label N-acetylgalactosamine (GalNac)-containing molecules which are selectively enriched on the surfaces of many GABAergic neurons (Naka-gawaet al, 1986a, b;Naegeleet al, 1987;Mulliganet al, 1989 (Arimatsu et al, 1987;Naegele et al, 1988). Monoclonal antibody Cat-301 labels a large proteoglycan restricted to cell bodies and dendrites of approximately 80% of the GABAergic neurons in cat area 17, as well as some pyramidal neurons (Hockfield and McKay, 1983;Hendry et al, 1988;Zaremba et al, 1989a).…”