Cross-modal innervation of primary visual cortex by auditory fibers in congenitally anophthalmic mice.

Auditory-visual cross-modal innervation was examined in control (sighted, ZRDCT-N) and congenitally anophthalmic (eyeless, ZRDCT-AN) mice using electrophysiological recording and pathway tracing with carbocyanine dyes. Electrophysiological data demonstrate that the primary visual cortex of congenitally eyeless, blind, mice receives auditory stimuli. Neuroanatomical data demonstrate a direct connection between the inferior colliculus (IC) and visual cortex.

Physiological and anatomical properties of the suprachiasmatic nucleus of an anophthalmic mouse.

Congenitally anophthalmic mice (ZRDCT-AN) have circadian rhythms which 'free-run' and are not light modulated. Their rhythms differ from those of controls in: duration of circadian period, length of active phase, and pattern/intensity of activity. Three different populations have been described based upon wheel-running: rhythmic with stable period, rhythmic with unstable period and arrhythmic.

The eyeless mouse mutation (ey1) removes an alternative start codon from the Rx/rax homeobox gene.

The eyeless inbred mouse strain ZRDCT has long served as a spontaneous model for human anophthalmia and the evolutionary reduction of eyes that has occurred in some naturally blind mammals. ZRDCT mice have orbits but lack eyes and optic tracts and have hypothalamic abnormalities. Segregation data suggest that a small number of interacting genes are responsible, including at least one major recessive locus, ey1.

The relationship between circadian rhythmicity and vasoactive intestinal polypeptide in the suprachiasmatic nucleus of congenitally anophthalmic mice.

To date, the search for the clock component that is both necessary and sufficient for generation of circadian rhythms has relied primarily on experimental interventions such as lesions and transplantation of fetal SCN. While these approaches have been fruitful, lesions disrupt adjacent host tissue and fiber pathways, and donor tissue is likewise subject to trauma during harvest and transplantation. The current investigation has used congenitally anophthalmic (eyeless) mice to ask whether VIP-IR SCN neurons are necessary and sufficient for generation of circadian rhythms.

Nonphotic entrainment of activity and temperature rhythms in anophthalmic mice.

Although it is more common to study the effects of light on circadian systems, nonphotic stimuli can also influence and entrain circadian clocks. Because anophthalmic mice (ZRDCT-AN) have a genetic mutation that prevents the development of the eyes, they do not respond to light or entrain to light-dark cycles. Thus, entrainment of anophthalmic mice requires a nonphotic zeitgeber (entraining stimulus).

Apoptosis in early ocular morphogenesis in the mouse.

Development of the eye requires complex interactions between tissues, extracellular matrix and growth factors. Most cells of the optic primordia grow and differentiate into discrete ocular structures; however, other cells have death as their developmental fate. The most common mechanisms of cell death are apoptosis and necrosis.

Daily patterns of running wheel activity in male anophthalmic mice.

Circadian rhythms are generated by the suprachiasmatic nuclei (SCN) and synchronized (entrained) to environmental light-dark cycles by the retinohypothalamic tract (RHT), a direct pathway from the retina to the suprachiasmatic nuclei. In anophthalmic mice, the optic primordia are resorbed between embryonic days 11.5 and 13, before retinal ganglion cells emerge.

Diurnal variations in vasoactive intestinal polypeptide-like immunoreactivity in the suprachiasmatic nucleus of congenitally anophthalmic mice.

The present study has combined recording of circadian locomotor rhythms with light microscopic immunocytochemistry for vasoactive intestinal polypeptide (VIP) in the suprachiasmatic nucleus (SCN) of congenitally anophthalmic mice. These mice, which never develop retinae or optic nerves and do not perceive light, are thus in constant darkness. Our data show a circadian rhythm in expression of VIP in the SCN of anophthalmic mice--expression is maximal during late subjective night/early subjective day and minimal in late subjective day/early subjective night.

The geniculohypothalamic pathway in a congenitally anophthalmic mouse.

In a previous study we described abnormalities in cytoarchitecture and vasoactive intestinal polypeptide distribution in the suprachiasmatic nucleus (SCN) of anophthalmic mice. However, the effect of anophthalmia on the geniculohypothalamic pathway, an important pathway for relay of photic information to the SCN, is not known. The present study examined the geniculohypothalamic pathway in congenitally anophthalmic and sighted control mice.

VIP-like immunoreactivity in the suprachiasmatic nuclei of a mutant anophthalmic mouse.

The suprachiasmatic nuclei (SCN) of mutant anophthalmic (strain ZRDCT-An) and sighted control mice was examined using light microscopic methods for cytoarchitecture and immunocytochemistry for vasoactive intestinal polypeptide (VIP). The SCN of the anophthalmic mice were asymmetrical, and quite variable in cytoarchitecture. Immunocytochemistry for VIP revealed strong staining of cells and fibers.

Neuropeptide Y-like immunoreactivity in the diencephalon of the little brown bat (Myotis lucifugus): localized variations with physiological state.

The current study used light microscopic immunocytochemistry to demonstrate and compare neuropeptide Y-like immunoreactivity (NPY-IR) in the diencephalon of the little brown bat (Myotis lucifugus) at different stages in its annual cycle of activity and hibernation. Animals were sacrificed in each of three discrete physiological states: euthermic, hypothermic, and hibernating. In general, NPY-IR was abundant in the hypothalamus and sparse in other diencephalic areas.

Unilateral enucleation alters vasoactive intestinal polypeptide-like immunoreactivity in the suprachiasmatic nucleus of the rat.

Adult Sprague-Dawley rats were unilaterally enucleated under deep anesthesia and sacrificed 3-11 months post-operatively. The brains were removed and the suprachiasmatic nuclei were evaluated for vasoactive intestinal polypeptide (VIP)-like immunoreactivity. Our data show that expression of VIP is reduced in the nucleus that is deprived of retinal input.

Synaptogenesis in the rat suprachiasmatic nucleus: a light microscopic immunocytochemical survey.

MabQ155, a monoclonal antibody against synaptophysin, has been used to conduct a light microscopic survey of synaptogenesis in the suprachiasmatic nucleus of the perinatal rat. Synaptophysin is an integral component of synaptic vesicle membranes which is expressed in growth cones and growth cone filopodia as well as in mature synapses. With the light microscope, mabQ155 immunoreactivity in growth cones can be distinguished from that in presynaptic terminals on the basis of the size of immunoreactive puncta.

Neuropeptide Y innervation of the cerebellum in the little brown bat (Myotis lucifugus).

Light microscopic immunocytochemistry for neuropeptide Y (NPY) has demonstrated the presence of a diffuse system of NPY-immunoreactive fibers in the cerebellum of Myotis lucifugus. These fibers gain access to the cerebellum by way of the superior cerebellar peduncle, and terminate on Purkinje cell dendrites and on neurons in the granule cell layer. The origin of cerebellar NPY and possible colocalization with norepinephrine are discussed.

The maturation of the somatostatin systems in the rat visual cortex.

The development of somatostatin-immunoreactive (SS) neurons and processes in the rat visual cortex (VC) was studied in animals from embryonic day 20 (E20) to postnatal day 21 (D21). Three distinct patterns of immunoreactivity were seen. From E20 to birth (D0), VC was characterized by a small number of mainly bipolar SS neurons throughout the cortical plate.

Cholecystokinin (CCK)-like immunoreactivity in the brain of the little brown bat (Myotis lucifugus).

The distribution of Cholecystokinin (CCK-8)-like immunoreactivity was mapped in the brain of the little brown bat, Myotis lucifugus, at three different and discrete levels of physiological activity: euthermic, hypothermic, and hibernating. Immunoreactive perikarya were present in the cerebral cortex, hippocampal formation, several nuclei of the olfactory and limbic systems, the ventral lateral geniculate nucleus, suprachiasmatic nucleus, medial geniculate nucleus, and caudate-putamen. Immunoreactive fibers were present in plexuses throughout the brain and in three major projection pathways: the medial forebrain bundle, the mammillary peduncle, and dorsal longitudinal fasciculus.

Effects of repeated administration of soman on schedule-controlled behavior and brain in the rat.

The effects of repeated SC administration of soman on schedule-controlled performance and brain pathology were studied in the rat. Soman suppressed response rates in both components of a multiple fixed interval 50-sec fixed-ratio 25 (mult. FI 50-sec FR 25) schedule of reinforcement, although all animals revealed marked tolerance to repeated drug administration.

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity in the suprachiasmatic nucleus of the perinatal rat.

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity was examined in the suprachiasmatic nucleus (SCN) of the perinatal rat using the unlabeled antibody enzyme method of Sternberger. Our results showed that VIP-like immunoreactivity was present in cells and fibers of the SCN prior to birth. Immunoreactive neurons at this time appeared morphologically immature, and their distribution differed somewhat from that seen in the adult SCN.

VIP-like immunoreactivity in the anterior hypothalamic area of a hibernating bat varies with physiological state.

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity in the anterior hypothalamic area (AHA) was studied in 15 bats which are seasonal hibernators, using the unlabeled antibody enzyme method of Sternberger. Our results showed that the density of immunoreactive fibers and terminal plexuses in the AHA was greatest in euthermic animals and decreased dramatically when body temperature and cardiac rate were depressed and animals entered hibernation.

Immunocytochemical localization of vasoactive intestinal polypeptide (VIP) in the brain of the little brown bat (Myotis lucifugus).

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity has been examined in the brain of the little brown bat, Myotis lucifugus, using light microscopic immunocytochemistry and the indirect antibody enzyme method of Sternberger. Animals were sacrificed at three different and discrete levels of physiological activity: euthermic, hypothermic and hibernating. The density and distribution of immunoreactive neurons and fibres was compared in the three animal groups with the aid of a computerized image analysis system.

Distribution of somatostatinlike immunoreactivity in the brain of the little brown bat (Myotis lucifugus).

The distribution of somatostatinlike immunoreactive (SLI) perikarya, axons, and terminals was mapped in subcortical areas of the brain of the little brown bat, Myotis lucifugus, using light microscopic immunocytochemistry. A preponderance of immunoreactivity was localized in reticular, limbic, and hypothalamic areas including: 1) in the forebrain: the bed nucleus of the stria terminalis; lateral preoptic, dorsal, anterior, lateral and posterior hypothalamic areas; amygdaloid, periventricular, arcuate, supraoptic, suprachiasmatic, ventromedial, dorsomedial, paraventricular, lateral and medial mammillary, and lateral septal nuclei; the nucleus of the diagonal band of Broca and nucleus accumbens septi; 2) in the midbrain: the periaqueductal gray, interpeduncular, dorsal and ventral tegmental, pretectal, and Edinger-Westphal nuclei; and 3) in the hindbrain: the superior central and parabrachial nuclei, nucleus incertus, locus coeruleus, and nucleus reticularis gigantocellularis. Other areas containing SLI included the striatum (caudate nucleus and putamen), zona incerta, infundibulum, supramammillary and premammillary nuclei, medial and dorsal lateral geniculate nuclei, entopeduncular nucleus, lateral habenular nucleus, central medial thalamic nucleus, central tegmental field, linear and dorsal raphe nuclei, nucleus of Darkschewitsch, superior and inferior colliculi, nucleus ruber, substantia nigra, mesencephalic nucleus of V, inferior olivary nucleus, inferior central nucleus, nucleus prepositus, and deep cerebellar nuclei.

Bilateral projections of neurons in the lateral geniculate nucleus and nucleus lateralis posterior to the visual cortex in the neonatal rat.

The projection from the lateral geniculate nucleus (LGN) and nucleus lateralis posterior (LP) to the visual cortex was examined in rat pups 3-7 days of age using the fluorescent tracers True Blue, Fast Blue and Nuclear Yellow. Our data provide the first evidence that (1) these projections are bilateral, (2) the ipsilateral projection from these nuclei to the visual cortex in the neonatal rat is well localized and is similar in distribution and organization to that reported by others in the adult and (3) bilaterally projecting geniculocortical cells are morphologically heterogeneous; bilaterally projecting cells in LP are morphologically homogeneous.

Somatostatin (SRIF)-like immunoreactivity in subcortical and cortical visual centers of the rat.

The distribution of neuronal elements containing immunoreactive somatostatin (I-SRIF) in the rat central visual pathway was examined by light-microscopic immunocytochemistry. These studies were concerned with the location and morphology of neurons and innervated cells and the distribution of fiber and terminal plexuses in the primary visual cortex (area 17), visual association areas 18 and 18a, the superior colliculus, the lateral geniculate nucleus, and the pretectum. In the superior colliculus, I-SRIF-containing fibers and perikarya were distributed predominantly in the superficial, or visual, layers; these elements were moderately dense and occupied the entire mediolateral extent of these layers.

A Golgi study of cell morphology in the deep layers of the human superior colliculus.

The superior colliculus is a morphologically and functionally complex center for integration of sensory and motor information which is utilized to orient the head and eyes toward stimuli in the environment. Recent studies have suggested that some of the afferent and efferent fiber pathways of the intermediate and deep layers are associated with particular populations of neurons as identified by size, shape and location. Immuno-cytochemical studies suggest a regional distribution of certain putative neurotransmitters in the superior colliculus.