Takashi Yamadori

Decreased Serotonin S2 and Increased Dopamine D2 Receptors in Chronic Schizophrenics

Serotonin S2 and dopamine D2 receptors in the prefrontal cortex and caudate nucleus of postmortem brains of chronic schizophrenics were studied using 3H-ketanserin and 3H-spiperone, respectively. In the prefrontal cortex of schizophrenics, we found a significant decrease in the maximum number of 3H-ketanserin binding sites (Bmax), with no change in the dissociation constant (Kd). Conversely, both Bmax and Kd of 3H-spiperone binding to the caudate nucleus were significantly increased in the schizophrenic patients. There were no differences in receptor indices between patients who were taking neuroleptics until their death and those who had taken none for 2 months or more prior to death. These findings suggest that alterations in S2 receptors in the prefrontal cortex may reflect the disease process, per se, and that the increase in the number of D2 receptors in the caudate nucleus of schizophrenics is not due solely to neuroleptic medication.

Efferent fibers of the habenula and stria medullaris thalami in rats

Abstract Lesions were produced in the stria medullaris thalami and habenula of albino rats by the electrocoagulating method to study the efferent fibers of the habenula and stria medullaris thalami as well as the reciprocal fibers in the stria. Animals were killed on the fifth day after the operation by vascular perfusion with a 10% formol solution, and degenerating nerve fibers in the brain were traced by the Nauta-Gygax technique. Efferent fibers of these structures were distributed in the bilateral striae medullares thalami and habenulae. The fibers in the striae could be traced to the lateral preoptic and lateral hypothalamic areas of each side and were considered to be reciprocal fibers which take their course contrary to the main stream of fibers. Other regions receiving efferent fibers of the stria medullaris thalami and habenula were ipsilateral nucleus medialis dorsalis, ipsilateral nucleus parafascicularis, ipsilateral fasciculus retroxflexus, and nucleus interpeduncularis. It seemed that there was not so much difference between the distribution of efferent fibers of the stria medullaris thalami and that of the habenula.

Corticonuclear and corticovestibular projections from the uvula in the albino rat: differential projections from sublobuli of the uvula

The organization of the corticonuclear and corticovestibular projections from the uvula was investigated in the albino rat by an autoradiographic method. The corticonuclear fibers from sublobule a of the uvula terminated in the caudoventral part of the medial cerebellar nucleus, and the caudomedial part of the posterior interpositus nucleus with mediolateral topography. The medial and lateral portions of the sublobule projected to the medial cerebellar and posterior interpositus nuclei, respectively. The corticovestibular fibers from sublobule a terminated in the dorsal and rostral parts of the superior vestibular nucleus, the dorsal part of the lateral vestibular nucleus, and the caudomedial part of the spinal vestibular nucleus. However, the corticonuclear fibers from sublobuli b and c of the uvula terminated additionally in the ventromedial part of the lateral cerebellar nucleus, while the corticovestibular fibers from these sublobuli terminated additionally in the subnucleus y of the vestibular complex, with probable termination in the medial vestibular nucleus. The cortical region which sent efferent projections to the ventromedial part of the lateral cerebellar nucleus and the subnucleus y was located laterally in sublobuli b and c of the uvula. These differential projection patterns from the dorsal and ventral sublobuli suggest the difference of the functional correlates between the sublobuli in the uvula.

A retrograde double-labelling study of retinal ganglion cells that project ipsilaterally to vLGN and LPN rather than dLGN and SC, in albino rat

We studied ipsilaterally projecting, double-labeled retinal ganglion cells that have bifurcating axons by retrograde fluorescent double-labeling in albino rats. Ten albino (Wistar, Japan Ceca) rats of either sex, weighing 350-400 g were used. With the rats in a state of deep anesthesia, we pressure-injected 0.02 microliter of 15% Evans blue (EB) into the right ventral lateral geniculate nucleus (vLGN), and 4% Fluoro-gold (FG) iontophoretically into the right posterior lateral thalamic nucleus (LP). The animals were perfused with formol-saline 48-72 h later and both the brain and eyes were exercised. The brain was sectioned coronally, and each retina was removed and mounted flat on a glass slide. Double-labeled cells were found in the ventral temporal crescent of the retina. In one animal and total number of ipsilaterally labeled cells was 566, and the percentage of double-labeled vLGN and LP projecting cells, single-labeled vLGN projecting cells, and single-labeled LP projecting cells were 29.8, 58.8 and 11.3, respectively.

An Anomalous Cleido-Occipitalis Muscle

In a Japanese female cadaver, the occipital portion of the trapezius muscle (the cleido-occipitalis) was separated from the rest of the muscle by a triangular gap that resulted from a deficiency of the upper two thirds of the cervical portion on both sides. The right cleido-occipitals blended distally with the cervical fibers of the trapezius and had a normal insertion into the clavicle. The left cleido-occipitalis intermingled partially with the reduced cervical portion, and some of the conjoint fibers formed an independent accessory slip whose tendon inserted into the posterior aspect of the junction of the middle and medial thirds of the clavicle. The other conjoint fibers inserted into the clavicle and scapula as usual. This anomalous morphology may be attributed to a secondary degeneration of a portion of the trapezius anlage concomitant with an abnormal segregation of another portion during development.

An experimental anatomical study of the optic nerve fibers in the rat: Courses of the accessory optic tract

By means of silver impregnation and an HRP method, courses of the accessory optic tract were examined in albino and pigmented rats. The accessory optic tract is composed of 3 fasciculi: anterior, lateral and dorsal. The anterior fasciculus gives off fibers to the subthalamic nucleus and terminates in the medial terminal nucleus. The lateral fasciculus branches from the main optic tract at the level of the ventral nucleus of the lateral geniculate body and descends the lateral surface of the crus cerebri to enter the medial terminal nucleus after contributing a few fibers to the lateral terminal nucleus. The dorsal fasciculus originates from the brachium colliculi superioris and descends the posterior surface of the medial geniculate body and the posterolateral surface of the crus cerebri as an independent fasciculus to enter the medial terminal nucleus. This fasciculus supplies many fibers to the dorsal terminal nucleus.

Uncrossed retinal fibers terminating in the superior colliculus of the albino rat

Abstract The site of termination of uncrossed retinal fibers was examined in the superior colliculus of the albino rat. Sixty-eight male and female rats of Gifu, Donryu, Wistar and Sprague-Dawley strains from 9 days to 24 months of age were examined by means of a silver impregnation method for degenerating nerve fibers and the horseradish peroxidase method. In this study, terminals of uncrossed retinal fibers were observed in a small region from the posteromedial to the posterior part of the superficial gray stratum of the ipsilateral superior colliculus.

A retrograde fluorescent-labeling study of direct relationship between the limbic (anterodorsal and anteroventral thalamic nuclei) and the visual system in the albino rat

Injecting different fluorescent tracers into the right anterodorsal (AD)/anteroventral (AV) or AD/AV and the primary visual nuclei of dorsal lateral geniculate (dLGN) or superior colliculus (SC), a direct projection from the left retina to these anterior thalamic nuclei was ascertained in the central part of ventro-nasal retinal quadrant. Single-labeled cells were of small type. No double-labeled cells were demonstrated.

A Developmental Study of Reflex and Activity in Rats with Microcephaly Induced by Prenatal Methylazoxymethanol Acetate (MAM) Treatment

Pregnant Wistar rats were given a single i. p. injection of 30 mg/kg methylazoxymethanol (MAM) acetate or saline on day 13 of pregnancy (vaginal plug = day 0). All offspring were subjected to reflex tests during the preweaning period (surface righting reflex, from 3 to 12 days of age; negative geotaxis reflex, from 5 to 12 days of age), and then selected male rats were subjected to open‐field test during the postweaning period (from 21 to 35 days of age). The MAM‐treated rats showed significantly longer latencies in the both reflex tests, and also significant hyperactivity in the open‐field test. These behavioral alterations were analyzed in relation to the large size reduction in the cerebral cortex and the morphological abnormalities of the hippocampus in the MAM‐treated rats.

Retrograde double-labeling study of retinal ganglion cells from the ipsilateral vLGN and SC in the albino rat

Retinal ganglion cells with branches to the ipsilateral ventral lateral geniculate nucleus (vLGN) and superior colliculus (SC) were studied by retrograde fluorescent double-labeling. Double-labeled cells were found in the ventral temporal crescent of the retina, with a few ipsilaterally projecting single-labeled cells scattered in this area. Single-labeled vLGN-projecting cells were found predominantly in the ventral-temporal crescent and to a lesser extent in the temporal and dorsotemporal octant. SC-projecting cells were present predominantly in the ventral-temporal crescent and to a lesser extent in the ventral and ventronasal octant. Our best animal model had 2200 ipsilaterally labeled cells. There were 451 (20.5%) double-labeled vLGN and SC-projecting cells, 561 (25.5%) single-labeled vLGN-projecting cells, and 1186 (53.9%) single-labeled SC-projecting cells.