Monoclonal Antibody Cat-301 Research Articles

Purkinje cell axon collaterals terminate on Cat-301+ neurons in Macaca monkey cerebellum

The monoclonal antibody Cat-301 identifies perineuronal nets around specific neuronal types, including those in the cerebellum. This report finds in adult Macaca monkey that basket cells in the deep molecular layer; granule cell layer (GCL) interneurons including Lugaro cells; large neurons in the foliar white matter (WM); and deep cerebellar nuclei (DCN) neurons contain subsets of Cat-301 positive (+) cells. Most Cat-301+ GCL interneurons are glycine+ and all are densely innervated by a meshwork of calbindin+/glutamic acid decarboxylase+ Purkinje cell collaterals and their synapses. DCN and WM Cat-301+ neurons also receive a similar but less dense innervation. Due to the heavy labeling of adjacent Purkinje cell dendrites, the innervation of Cat-301+ basket cells was less certain. These findings suggest that several complex feedback circuits from Purkinje cell to cerebellar interneurons exist in primate cerebellum whose function needs to be investigated. Cat-301 labeling begins postnatally in WM and DCN, but remains sparse until at least 3 months of age. Because the appearance of perineuronal nets is associated with maturation of synaptic circuits, this suggests that the Purkinje cell feedback circuits develop for some time after birth.

Architectonic subdivisions of the inferior pulvinar in New World and Old World monkeys.

Architectonic subdivisions of the inferior pulvinar (PI) complex were delineated in New World owl and squirrel monkeys and Old World macaque monkeys. Brain sections were processed for Nissl substance, myelin, cytochrome oxidase (CO), acetylcholinesterase (AChE), calbindin-D28K (Cb), or with the monoclonal antibody Cat-301. In all three primates, we identified the posterior nucleus (PIp) and the medial nucleus (PIm) of previous reports, and divided the previously recognized central nucleus (PIc) into two subdivisions, medial (PIcM) and lateral (PIcL). Each nucleus had several features that allowed it to be readily distinguished. (1) PIp was dark in Cb, and moderately dark in AChE and CO preparations. (2) PIm was Cb light, and AChE and CO dark. (3) PIcM was Cb dark, and AChE and CO light. (4) PIcL was Cb moderate with a scattering of dark neurons, and moderately dark for AChE and CO. (5) In sections processed for Cat-301, PIm in macaque monkeys and PIcM and PIp in squirrel monkeys stained darkly, while little staining was apparent in owl monkeys. The results allowed subdivisions of the inferior pulvinar to be more clearly defined, homologized, and compared across taxa. All monkeys appear to have the same four subdivisions of the PI, although properties vary.

The global pattern of cytochrome oxidase stripes in visual area V2 of the macaque monkey.

In primate visual area V2, histochemical staining for cytochrome oxidase (CO) reveals a tripartite pattern of densely labeled thick and thin stripes separated by pale interstripes. This modularity is believed to be related to functionally distinct processing streams that course through the hierarchy of visual areas. Here, we studied the overall pattern of CO stripes in V2 of the macaque monkey, using tissue that had been physically unfolded and flattened prior to histological sectioning. CO stripes were identified on the basis of their physical dimensions and on their differential immunoreactivity for the monoclonal antibody Cat-301. We observed several distinctive features of compartmental organization in V2. The most prominent was a dorso-ventral asymmetry in the stripe pattern, occurring in the majority of cases studied. In dorsal V2, most stripes measure approximately 10 mm in length and run roughly orthogonal to both the posterior and anterior borders of V2. In contrast, many stripes in ventral V2 have a curved or oblique trajectory, and some extend up to 20 mm in length. Stripes following a curved trajectory often become nearly parallel to the anterior border of V2. These differences imply an asymmetry in how the visual field maps onto dorsal versus ventral stripes. Occasionally, thin stripes fail to alternate with thick stripes but instead occur next to one other, separated only by interstripes. In three most complete reconstructions, we found that unfolded V2 is approximately 110 mm in length, approximately 900 mm2 in surface area, and that it contains approximately 28 complete sets of stripes (one thick, one thin and two interstripes), yielding an average of approximately 4 mm per set of stripes. The maximum width of ventral V2 (13-14 mm) exceeds that of dorsal V2 (10 mm), and there is a consistent narrowing of V2 in the region of foveal representation (3-5 mm).

A Family of Activity-Dependent Neuronal Cell-Surface Chondroitin Sulfate Proteoglycans in Cat Visual Cortex

Monoclonal antibody Cat-301 recognizes a chondroitin sulfate proteoglycan (CSPG) expressed on the extracellular surface of cell bodies and proximal dendrites of specific subsets of neurons in many areas of the mammalian CNS, including the cat visual cortex. The Cat-301 CSPG is first detected at the close of the critical period in development, a period during which the pattern of neuronal activity determines the mature synaptic circuitry and neuronal phenotype. In the cat visual cortex, dark-rearing from birth prolongs the duration of the critical period and attenuates the expression of the Cat-301 antigen, implicating the Cat-301 CSPG in the cellular mechanisms that terminate the period of synaptic plasticity. Because the Cat-301 antigen is expressed on only a limited subset of neurons, we have further examined the molecular heterogeneity among neuronal cell-surface CSPGs and have asked (1) whether other neuronal subsets carry distinct CSPGs and (2) whether the activity-dependent expression of the Cat-301 CSPG is a property generalizable to related cell-surface CSPGs. Here, we report two new monoclonal antibodies, Cat-315 and Cat-316, which together with Cat-301 define a family of at least seven related yet distinct CSPGs. These three antibodies define nonidentical subsets of neurons in the cat visual cortex. The expression of normal levels of these CSPGs is reduced by dark-rearing. Together, these data show that the family of cell-surface CSPGs is molecularly diverse, that different sets of neurons express distinct complements of cell-surface antigens, and that the regulation of CSPG expression by activity may be a general feature of neuronal cell-surface CSPGs.

Distribution of neurons projecting to the superior colliculus correlates with thick cytochrome oxidase stripes in macaque visual area V2.

In visual area V2 of macaque monkeys, cytochrome oxidase (CO) histochemistry reveals a pattern of alternating densely labeled thick and thin stripe compartments and lightly labeled interstripe compartments. This modular organization has been associated with functionally separate pathways in the visual system. We examined this idea further by comparing the pattern of CO stripes with the distribution of neurons in V2 that project to the superior colliculus. Visually evoked activity in the superior colliculus is known to be greatly reduced by blocking magnocellular but not parvocellular layers of the lateral geniculate nucleus (LGN). From previous evidence that V2 thick stripes are closely associated with the magnocellular LGN pathway, we predicted that a significant proportion of V2 neurons projecting to the superior colliculus would reside in the thick stripes. To test this prediction, the tangential distribution of retrogradely labeled corticotectal cells in V2 was compared with the pattern of CO stripes. We found that neurons projecting to the superior colliculus accumulated preferentially into band-like clusters that were in alignment with alternate CO dense stripes. These stripes were identified as thick stripes on the basis of their physical appearance and/or by their affinity to the monoclonal antibody Cat-301. A significantly smaller proportion of labeled cells was observed in thin and interstripe compartments. These data provide further evidence that the spatial distribution of subcortically projecting neurons can correlate with the internal modular organization of visual areas. Moreover, they support the notion that CO compartments in V2 are associated with functionally different pathways.

The cervicothalamic tract terminates in Cat301-sparse regions of the cat VPL.

The termination pattern of the cervicothalamic tract (CTI), labelled with anterogradely transported WGA-HRP, was compared with the immunolabelling pattern obtained with the monoclonal antibody Cat301 in adjacent sections through the ventral posterolateral nucleus (VPL). CTT terminations are located in peripheral parts of the medial and lateral parts of the VPL (VPLm and VPL1), being more extensive in the caudal than in the rostral parts of the subnuclei, and in the dorsal part of VPL1 and dorsolateral part of VPLm, regions that are all sparse in CAt301 immunoreactivity. Central regions of the VPL with dense Cat301 immunolabelling contain only very sparse CTT termination. Thus, our findings show that the CTT innervates a compartment of the VPL that is characterized by sparse Cat301 immunoreactivity.

Effects of early periods of monocular deprivation and reverse lid suture on the development of Cat-301 immunoreactivity in the dorsal lateral geniculate nucleus (dLGN) of the cat.

During certain sensitive periods early in postnatal life, the anatomical and physiological development of the central visual pathways of cats and monkeys can be affected by the nature of an animal's early visual experience. In the last few years, studies have been started on some of the molecular and biochemical events that underlie the many functional changes induced by early selected visual deprivation in the visual cortex of kittens. In this respect, the monoclonal antibody Cat-301 provides a potentially powerful tool, because it recognizes in the cat dorsal lateral geniculate nucleus (dLGN) a proteoglycan associated with the surface of a particular class of cells, namely Y cells. In the dLGN, the Cat-301 proteoglycan appears late in postnatal development, and it expression has been shown to be experience dependent in both the dLGN and visual cortex (M. Sur, D. Frost, and S. Hockfield, 1988, J. Neurosci. 8:874-882; A. Guimaraes, S. Zaremba, and S. Hockfield, 1990, J. Neurosci. 10:3014-3024). We have explored further the experience-dependent nature of Cat-301 expression in the dLGN with a view to establishing a biochemical correlate of the many functional changes induced by early monocular deprivation and its reversal in the kitten visual system. In addition to demonstrating differences in Cat-301 expression between deprived and nondeprived laminae of the dLGNs of kittens monocularly deprived to only 4 or 5 weeks of age, the magnitude of the laminar difference was found to increase as the period of deprivation was extended. Moreover, monocularly deprived kittens that subsequently received long periods of reverse lid suture exhibited a reversal of the pattern of immunoreactivity, so that the greatest immunoreactivity occurred in laminae innervated by the initially deprived eye. However, possibly the most surprising and important finding was the extremely low levels of immunoreactivity observed in both A laminae of monocularly deprived animals that had received relatively short periods of reverse lid suture. These data suggest that Y cell development can be drastically altered depending on the time of initiation of the period of reverse lid suture and its duration.

Electrical Activity in the Neuromuscular Unit Can Influence the Molecular Development of Motor Neurons

During the first few weeks of postnatal life spinal motor neurons develop electrophysiological, morphological, and molecular features that are characteristic of adult motor neurons. To understand how the acquisition of the mature neuronal phenotype is regulated, we have examined the expression of the motor neuron cell surface proteoglycan recognized by monoclonal antibody Cat-301 in the hamster. Previously we found that Cat-301 immunoreactivity is not present on motor neurons at birth and that by the end of the second postnatal week all motor neurons are Cat-301-positive. Surgical and pharmacological lesion studies have shown that the onset of Cat-301 expression depends upon input from both large-diameter primary afferents and from supraspinal afferents. Once the Cat-301 proteoglycan is expressed on motor neurons, its continued expression is independent of these inputs. These studies suggested that motor neuron maturation depends upon the coordination of several afferent inputs during the first postnatal weeks of life. Our previous studies could not address whether segmental and descending afferents (i) provide a chemical signal (such as a trophic factor) or (ii) confer a pattern of neuronal activity upon motor neurons that then results in the expression of the Cat-301 proteoglycan. The present experiments examine the role of electrical activity in motor neuron maturation. In normal animals, all sciatic motor neurons are Cat-301-positive by Postnatal Day 19 (P19). Chronic application of the sodium channel blocker, tetrodotoxin (TTX), to the sciatic nerve in neonatal animals reduces the percentage of Cat-301-positive motor neurons found at P21 by one-third. This reduction is not due to a nonspecific inhibition of all protein synthesis, because the expression of two other motor neuron antigens proceeds normally in TTX-treated neonates. Blockade of neuromuscular transmission in neonates by Botulinus toxin A also reduces the percentage of Cat-301-positive motor neurons. Cat-301 expression is not tied simply to neuronal activity, because chronic application of TTX to the sciatic nerve, or Botulinus toxin A to muscles, in the adult does not reduce Cat-301 expression. These findings indicate that electrical activity generated within the neuromuscular unit in early postnatal life can influence the acquisition of mature molecular properties by motor neurons.

Monoclonal antibody Cat-301 selectively identifies a subset of nuclei in the cat's somatosensory thalamus.

Recently it has been demonstrated that the monoclonal antibody Cat-301 is capable of identifying functionally related neurons in the mammalian visual thalamus. We have examined the possibility that this antibody might display a similar capacity in nonvisual thalamic areas. We demonstrate that in the cat's somatosensory thalamus the distribution of Cat-301-positive cells and neuropil is restricted to a subset of nuclei. These include the ventroposterior medial, ventroposterior lateral, and ventroposterior inferior nuclei. Staining with Cat-301 provides a clear visualisation of the entire somatotopic map within these nuclei. The somatosensory sector of the thalamic reticular nucleus and the perireticular nucleus, which may have a somatosensory sector, are also Cat-301-positive. In contrast, cells that do not express the Cat-301 antigen are located in the ventroposterior oralis nucleus, the ventroposterior shell region, the medial and lateral divisions of the posterior nuclear group, and the inner small cell region adjacent to the thalamic reticular nucleus. In comparison with previous physiological studies, cells that express the Cat-301 antigen most likely represent subpopulations in only a few of the somatic submodality-specific groups. These include cells in the small-field and Pacinian cutaneous-responsive groups, excluding cells in the wide-field cutaneous-, muscle-, joint-, and noxious-responsive groups. Taken together these findings indicate that monoclonal antibody Cat-301 is capable of selectively identifying neurons with distinct functional properties in the mammalian somatosensory thalamus.

Monoclonal antibody cat‐301 identifies Y‐cells in the dorsal lateral geniculate nucleus of the cat

In mammalian visual pathways, information is carried in parallel channels from the retina through the visual thalamus to visual cortex. The cat's visual pathway comprises at least three major channels that begin with the X, Y, and W ganglion cells in the retina. In the dorsal lateral geniculate nucleus (LGN) of the thalamus, neurons in the X, Y, and W channels receive input from their retinal counterparts and can be discriminated from one another on the basis of their anatomical and physiological properties. The search for molecular properties that might correlate with anatomically or physiologically defined classes of neuron has been a major area of research in recent years. Monoclonal antibody Cat-301 recognizes a neuronal surface-associated proteoglycan in many areas of the mammalian central nervous system. In the cat LGN Cat-301 immunoreactivity is restricted to a subset of neurons. We show here that the distribution, size, morphology, and cortical projection pattern of Cat-301-positive LGN neurons match those previously described for Y-cells. Taken together with our previous studies of the development of immunoreactivity and the sensitivity of Cat-301 staining to visual deprivation, these studies suggest that Cat-301 specifically recognizes Y-cells in the cat LGN. These results indicate that neurons within a physiologically and anatomically defined cell class share a molecular property. They further suggest that differences in molecular traits may reflect, and possibly subserve, differences in anatomical and physiological characteristics.

Molecular and morphological changes in the cat lateral geniculate nucleus and visual cortex induced by visual deprivation are revealed by monoclonal antibodies Cat-304 and Cat-301

Monoclonal antibody Cat-301 recognizes a surface-associated proteoglycan on subsets of neurons in the mammalian CNS (Hockfield and McKay, 1983). The expression of Cat-301 immunoreactivity on Y cells in the cat LGN is sharply reduced by early visual deprivation (Sur et al., 1988). We employed an immunosuppression strategy (Hockfield, 1987) to further study alterations in the expression of experience-dependent molecules. Newborn BALB/c mice were injected with LGN from dark-reared cats to induce a suppression of the immune response to antigens expressed in visually deprived animals. These mice were then immunized with LGN from normal cats to elicit an immune response to antigens with an expression dependent on normal early visual experience. This strategy permitted the generation of monoclonal antibody Cat-304, which recognizes a surface-associated antigen on neuronal cell bodies and proximal dendrites, and which appears histologically identical to Cat-301. Further analyses show that Cat-304 and Cat-301 recognize different epitopes on the same 680-kDa chondroitin sulfate proteoglycan. We examined the effects of early visual deprivation on Cat-304 immunoreactivity in the LGN and visual cortex of cats. In LGN from normal cats, Cat-304 labels neurons in layers A, A1, and C, in interlaminar zones, and in the medial interlaminar nucleus. In LGN from dark-reared cats, the number of antibody-positive neurons is markedly reduced, and the cross-sectional area of the remaining positive neurons is smaller than normal. In cortical area 17 of normally reared cats, Cat 304-positive neurons are densely distributed in 2 bands, in layers IV and V/VI. Labeled neurons are also present in layers II and III. In area 17 of dark-reared cats, the number of antibody-positive neurons is reduced. The reduction in the number of labeled neurons is most pronounced in layers II/III and V/VI. Antibody-positive neurons are smaller in all cortical layers of dark-reared cats. The changes in the expression of Cat-301 immunoreactivity in dark-reared visual cortex and LGN are identical to those of Cat-304. The laminar differences in the effect of dark rearing on Cat-301 and Cat-304 expression in the visual cortex provides support for the suggestion that layer IV of cortical area 17 may be less susceptible to prolongation of plasticity by dark rearing than layers II/III and V/VI. Further, the biochemical and histological studies reported provide evidence that early visual experience regulates protein expression in the cat LGN and visual cortex.

Antibody labeling of functional subdivisions in visual cortex: Cat-301 immunoreactivity in striate and extrastriate cortex of the macaque monkey

We have examined the distribution of immunoreactivity for the monoclonal antibody Cat-301 in visual cortex of the macaque monkey. Remarkably, those portions of striate cortex (V1) and extrastriate cortex that are most immunoreactive for Cat-301 are anatomically interconnected and are dominated by inputs arising from the magnocellular layers of the LGN (which are themselves highly immunoreactive). In particular, we found that a band of Cat-301 labeled neurons known to exist in layer 4 of V1 is centered on the boundary between layers 4C alpha and 4B and thus includes portions of both the primary target of the magnocellular LGN and its subsequent relay through layer 4B. We also demonstrated consistently strong Cat-301 immunoreactivity in all three extrastriate targets of layer 4B: areas V3, MT, and the cytochrome-oxidase (CO) enriched thick stripes of V2. In V2, there was a close correlation between Cat-301 labeling and clusters of cells projecting to MT but not to V4. This was true even in regions where the CO pattern was equivocal or irregular, indicating that Cat-301 is a more reliable marker than CO for the thick-stripe subregions of V2. Finally, we found strong Cat-301 immunoreactivity in at least parts of areas V3A, the MST complex, and the posterior parietal complex, but not in area V4 or inferotemporal cortex. The molecular specificity revealed by this single marker thus correlates with functionally specific subdivisions at each hierarchical level over nearly the entire known extent of the visual pathway in macaques. This supports the notion that these subdivisions form an anatomically, physiologically, and now molecularly distinct pathway known as the M-stream.

Molecular differences among neurons reveal an organization of human visual cortex.

Monoclonal antibody Cat-301 recognizes a cell-surface proteoglycan on subsets of neurons in several areas of the cat and macaque monkey central nervous system. In striate and extrastriate visual cortex of the macaque, the distribution of Cat-301-positive neurons demonstrates features of cellular organization that correlate with previously described functional subdivisions. Here we show that Cat-301 recognizes an antigen in human cortex that is closely related, if not identical, to the antigen in laboratory animals. Further, we use Cat-301 to demonstrate an organization of molecularly defined neurons in primary and secondary visual cortex (cortical areas V1 and V2) of the human. The organization demonstrated with Cat-301 in human area V1 correlates with the organization of ocular dominance columns demonstrated by cytochrome oxidase histochemistry. The organization demonstrated with Cat-301 in human area V2 correlates with the thick stripes of the cytochrome oxidase pattern. The present observations provide evidence for a visual pathway in human cortex homologous to the magnocellular pathway in macaque, a pathway involved in processing the low-contrast, achromatic, and moving components of visual stimuli.

Large diameter primary afferent input is required for expression of the cat-301 proteoglycan on the surface of motor neurons

The expression of a cell surface proteoglycan, recognized by monoclonal antibody Cat-301, is regulated by neuronal activity in early life. Here we report that the expression of the Cat-301 proteoglycan on motor neurons depends on primary afferent input in the early postnatal period. Previously we showed that in two different systems, Y-cells in the cat lateral geniculate nucleus and motor neurons in the hamster spinal cord, the expression of the Cat-301 antigen requires neuronal activity during a circumscribed period in development. Disrupting the activity of Y-cells (by dark rearing or by monocular lid suture) or of motor neurons (by sciatic nerve crush or by spinal cord lesion) during the early postnatal period prevents Cat-301 expression. Disrupting neuronal activity in adults has no effect on Cat-301 expression. The onset of Cat-301 expression corresponds to the end of the period of activity-dependent development. In order to further dissect the components of the segmental reflex arc required for the expression of Cat-301 on motor neurons, here we evaluated the effect of deafferentation by dorsal rhizotomy. In adult animals two weeks after deafferentation all sciatic motor neurons continue to express Cat-301. In contrast, in neonates two weeks after deafferentation the normal developmental expression of Cat-301 is reduced and less than 50% of sciatic motor neurons express Cat-301. We next selectively lesioned the small diameter afferents using the neurotoxin capsaicin. In contrast to rhizotomy, neonatal deletion of small diameter afferents has no effect on the development of Cat-301 expression on motor neurons. These results imply that input relayed by large diameter primary afferents (probably those conveying muscle and/or joint information) is required for normal maturation of motor neuronal properties during early life. They also provide further evidence for activity-dependent maturation of motor neurons.

Distribution of cat‐301 immunoreactivity in the frontal and parietal lobes of the macaque monkey

The distribution of the monoclonal antibody Cat-301 was examined in the frontal and parietal cortex of macaque monkeys. In both regions the distribution was uniform within cytoarchitecturally defined areas (or subareas) but varied between them. In all areas, Cat-301 labeled the soma and proximal dendrites of a restricted population of neurons. In the frontal lobe, Cat-301-positive neurons were intensely immunoreactive and present in large numbers in the motor cortex (area 4), premotor cortex (area 6, excluding its lower ventral part), the supplementary motor area (SMA), and the caudal prefrontal cortex (areas 8a, 8b and 45). In the parietal lobe, large numbers of intensely immunoreactive neurons were evident in the post-central gyrus (areas 1 and 2), the superior parietal lobule (PE/5), and the dorsal bank (PEa), fundus (IPd), and deep half of the ventral bank (POa(i] of the intraparietal sulcus (IPS). Two major patterns of laminar distribution were evident. In motor, supplementary motor, premotor (excluding the lower part of its ventral division), and the caudal prefrontal cortex (Walker's areas 8a, 8b and 45), and throughout the parietal cortex (with the exception of area 3), Cat-301-positive neurons were concentrated in the lower part of layer III and in layer V. The laminar positions of labeled cells in these areas were remarkably constant, as were the proportions of labeled neurons that had pyramidal and nonpyramidal morphologies (means of 30.2% and 69.8%, respectively). In contrast, in prefrontal areas 9, 10, 11, 12, 13, 14, and 46, in the cingulate cortex (areas 23, 24 and 25), and in the lower part of the ventral premotor cortex, Cat-301-positive neurons were spread diffusely across layers II to VI and a mean of 3.6% of the labeled neurons were pyramidal while 96.4% were nonpyramidal. Area 3 was unique among frontal and parietal areas, in that the labeled neurons in this area were concentrated in layers IV and VI. The areas in the frontal lobe which were heavily labeled are thought to be involved in the control of somatic (areas 4 and 6) and ocular (areas 8 and 45) movements. Those in parietal cortex may be classified as areas with somatosensory functions (1, 2, PE/5, and PEa) and areas which may participate in the analysis of visual motion (Pandya and Seltzer's IPd and POa(i), which contain Maunsell and Van Essen's VIP). The parietal somatosensory areas are connected to frontal areas with somatic motor functions, while POa(i) is interconnected with the frontal eye fields (8a and 45).(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of an activity-dependent, neuronal surface proteoglycan identified with monoclonal antibody Cat-301

Monoclonal antibody Cat-301 was previously shown to recognize a surface-associated antigen on subsets of mammalian CNS neurons whose expression is regulated by neuronal activity early in an animal's postnatal life. We now present the partial purification and characterization of the Cat-301 antigen and demonstrate that it is a chondroitin sulfate proteoglycan. Extracellular localization of the Cat-301 epitope is demonstrated by staining live, intact neurons in situ. Extraction of the antigen from membranes in the absence of detergent indicates that it is either a peripheral membrane protein or a component of an extracellular matrix. The Cat-301 antigen migrates on Western blots of SDS gels with a molecular weight of ∼680,000 dalton and is purified by DEAE chromatography and Sepharose gel filtration in 8 M urea (pH 4.9) buffer. The antigen is sensitive to chondroitinase ABC, indicating that it is a chondroitin sulfate proteoglycan. Furthermore, we provide strong evidence that the biochemically characterized antigen is indeed the histologically detected species by using a second antibody, Cat-304, that produces, immunohistological staining patterns identical to those of Cat-301 and reacts with the purified antigen, but at a distinct epitope. Our earlier developmental findings and the present localization and biochemical results suggest that the antigen may play a role in the maturation of functional connections between neurons, perhaps through stabilization of axosomatic and axodendritic synapses.

Molecular evidence for early activity-dependent development of hamster motor neurons

Monoclonal antibody Cat-301 recognizes a surface antigen on subsets of neurons in many areas of the mammalian CNS, including Y-cells in the cat dorsal lateral geniculate nucleus (LGN) and spinal motor neurons in several species. We have shown previously that the Cat-301 antigen is expressed relatively late in postnatal development, with a time course that matches that of late developmental features of both LGN and spinal cord neurons. The developmental time course of the expression of the Cat-301 antigen in the LGN correlates with the period during which visual deprivation can alter LGN Y-cells. Neonatal visual deprivation (by monocular lid suture or dark rearing) suppresses Cat-301 expression on Y-cells, while deprivation in adult animals has no effect on antigen expression. These results suggested that the onset of Cat-301 immunoreactivity provides a positive molecular marker for the end of a critical period in cat visual system development. To determine if Cat-301 might be a general marker for experience-dependent development in other areas of the CNS we have examined antigen expression on hamster spinal cord motor neurons. Here, we report that Cat-301 immunoreactivity develops on hamster motor neurons between postnatal days 7 and 14. Altering neuromuscular activity by sciatic nerve crush or thoracic hemicordotomy inhibits Cat-301 expression on motor neurons if performed before the onset of Cat-301 immunoreactivity. Other motor neuron antigens are unaffected by this procedure. In adult animals, nerve crush or cordotomy has no effect on Cat-301 immunoreactivity, demonstrating that Cat-301 expression is not simply dependent on ongoing neural activity. These observations suggest that motor neurons, like LGN neurons, require some pattern of neuronal activity during a critical period in development and, further, that the phenotypic changes in neurons consequent to early activity are reflected by the expression of specific molecules. The identification and characterization of such molecules may yield a description of the molecular mechanisms of experience-dependent development.

Expression of a surface-associated antigen on Y-cells in the cat lateral geniculate nucleus is regulated by visual experience

The monoclonal antibody Cat-301, generated against cat spinal cord (McKay and Hockfield, 1982), recognizes a surface-associated antigen that, in the cat lateral geniculate nucleus (LGN), is selectively expressed on Y-cells (Hockfield et al., 1983; Hendry et al., 1984; Sur et al., 1984). We now report that the antigen recognized by Cat-301 appears late in development, along a time course similar to that described for the maturation of the physiological properties of Y-cells in the LGN, and that its expression is sharply reduced by monocular lid suture or dark-rearing from birth, 2 visual deprivation procedures that lead to a reduction in the proportion of Y-cells recorded physiologically in the LGN (Sherman et al., 1972; Kratz et al., 1979; reviewed in Sherman and Spear, 1982). Monocular lid suture in the adult has no effect on Cat-301 antigen levels or, as previously reported (Sherman et al., 1972), on the proportion of physiologically recorded Y-cells. In addition, reversing the monocular deprivation in adulthood by opening the neonatally sutured eye and suturing closed the previously normal eye for 6 months restores neither normal levels of Cat-301 labeling nor, as previously reported (Geisert et al., 1982), the proportion of recordable Y-cells. The development of Cat-301 immunoreactivity thus parallels the development of LGN Y-cell physiology. The relative reduction in levels of immunoreactivity consequent to neonatal, but not adult, visual deprivation shows that Cat-301 antigen expression does not simply reflect the level of visually evoked electrical activity in the LGN, but rather reflects a process that depends on the nature of visual experience early in life.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuronal populations stained with the monoclonal antibody Cat-301 in the mammalian cerebral cortex and thalamus

The monoclonal antibody Cat-301 was used to examine neurons in the cerebral cortex and dorsal thalamus of several mammalian species, including Old World monkeys, cats, bush babies, guinea pigs, and rats. In each species, subpopulations of cortical and thalamic neurons are stained along the surfaces of their somata and proximal dendrites. Cat-301-positive cortical neurons include specific groups of pyramidal cells (e.g., corticospinal but not corticobulbar or callosal neurons in the monkey sensory-motor areas) and certain GABA-immunoreactive nonpyramidal cells. In the thalamus, the relay neurons projecting to the cortex and not the intrinsic neurons are stained. The Cat-301-positive neurons are nonhomogeneously distributed in the cat and monkey cortex and thalamus. In the cortex, they are densely packed in 2 bands that in most areas include layers III and V, but that in primary sensory areas include layers IV and VI. Because the density of stained neurons, their distribution, and the intensity of their staining vary among cortical areas, the borders between neighboring areas can often be detected by the differences in Cat-301 staining. Broader, regional differences are also readily apparent, for areas in the parietal and occipital lobes contain large numbers of intensely stained cells, but most areas in the frontal and temporal lobes contain fewer, more lightly stained neurons. The same broad differences are seen within the thalamus: only those nuclei reciprocally connected with intensely stained cortical areas contain large numbers of Cat-301-positive neurons. Differences among species include variations in cell density and distribution when a given cortical area or thalamic nucleus is compared between cats and monkeys. Greater differences are seen among the other species. Immunoreactive neurons in the cerebral cortex are sparse and lightly stained in guinea pigs, are restricted to the hippocampal formation in rats, and are very rare and isolated in bush babies. Similarly, Cat-301-positive thalamic neurons are restricted to only one or 2 nuclei in the guinea pig and rat and are extremely rare in the bush baby. Cat-301 stains organized groups of neurons in the cat and monkey cortex and thalamus. In addition to the laminar organization of stained cells in all cortical areas (see above), the Cat-301-positive neurons of monkey areas 17 and 18 are grouped into radial arrays. In area 17, clusters of stained cells are present in layers above and below layer IVC. These clusters lie at the centers of ocular dominance columns, within patches stained for cytochrome oxidase (CO). Most of these cells are also GABA-immunoreactive.(ABSTRACT TRUNCATED AT 400 WORDS)

A surface antigen expressed by a subset of neurons in the vertebrate central nervous system.

Many hypotheses for the specificity of connections in the nervous system postulate the presence of surface chemical differences between neurons. Hybridoma technology offers a potential route to identify such surface antigenic differences between neurons. Monoclonal antibody Cat-301 was one of a panel of antibodies generated by immunizing mice with homogenized adult cat spinal cord. At the light microscopic level, Cat-301 recognizes a subset of neurons in many areas of the vertebrate central nervous system. This report shows at the ultrastructural level that Cat-301 binds to a surface antigen on neurons in the intact vertebrate central nervous system. Cat-301-positive neurons carry the antigen on cell bodies and proximal dendrites but not on axons. Using secondary antibody labeled with horseradish peroxidase, we show that antibody binding sites are present along the surfaces of neurons and extend around presynaptic profiles but are excluded from the synaptic cleft. The distribution of the Cat-301 antigen at central synapses is similar to that described for some components of the extracellular matrix of the neuromuscular junction. This study demonstrates that a specific surface antigen is found on a subset of neurons and suggests that other surface markers may be present on other subsets of mammalian central nervous system neurons. Antibodies against this antigen and other surface antigens may allow insight into the mechanisms involved in the formation and maintenance of synaptic connections in the central nervous system.