Norihiko Onoda

Odor-induced fos-like immunoreactivity in the rat olfactory bulb

We here report odor-induced mapping patterns of c-fos-like protein (Fos) immunoreactivity in the rat olfactory bulb under urethane anesthesia. Regional patterns of cells with nuclei expressing Fos, plotted on a spread-out reconstruction of the mitral cell layer, were strikingly comparable to data from the 2-deoxyglucose method, by which different foci of the most-labelled glomeruli of metabolic activity were demonstrated using different odors. Cells in the glomerular, external plexiform, and granule cell layers were also labelled.

A monoclonal antibody specific for a subpopulation of retinal bipolar cells in the frog and other vertebrates.

One monoclonal antibody 115A10 (MAb 5A10) specifically stained a subpopulation of retinal bipolar cells in various vertebrates. In the bullfrog retina, MAb 5A10 stained the large bipolar cells, but not the small bipolar cells. Labeling of the living bipolar cells was observed in isolated cell preparation of the frog retina. MAb 5A10 can serve as a cell-specific marker of the bipolar cells.

Olfactory input to the lateral hypothalamus of the old world monkey

Responses of lateral hypothalamic neurons to 8 odors were studied in chronic unanesthetized old world monkeys (Macaca irus). Many neurons (54.5%) responded to a single odor only, and the number of neurons responding to 2, 3 and 4 odors decreased successively. No neuron responded to as many as 5 odors. Thus, the presence of olfactory input and a highly discriminative ability for odors were found in the lateral hypothalamic area (LHA). Neuronal responses to the same odors were also studied in the septum (Spt). In anesthetized old world monkeys, evoked potentials were recorded in the LHA and in areas of the Spt and the nucleus accumbens (Acc) during stimulation of the olfactory bulb (OB). When the Spt (and probably the Acc with it) was subsequently destroyed, OB-evoked potentials in the LHA disappeared. Next, by injecting horseradish peroxidase (HRP) into the LHA, an olfactory pathway to the LHA was examined. Labeled neurons were found mainly in the Spt and the Acc, and only partly in other areas. However, labeled neurons were scarcely found in the prepyriform (PPF)-entorhinal (ER) area or in the olfactory tubercle (OT). The present study thus shows that an olfactory pathway to the LHA passes through the Spt and probably also the Acc, but not through the PPF-ER areas nor through the OT in the old world monkey.

Striped pattern stained for cytochrome oxidase activity in the rabbit olfactory bulb

Summary Frontal sections from the rabbit olfactory bulb (OB) were stained for cytochrome oxidase (CO) activity. This technique revealed that the OB showed a concentric banding pattern of oxidative enzyme activity. This striped pattern was bilaterally symmetric and continued throughout the OB from rostral to caudal. The most densely stained band was in the middle of the external plexiform layer (EPL). Therefore, regarding differences in degrees of oxidative enzyme activity, the EPL can be divided into three sublayers. In the glomerular layer, individual glomeruli stained as isolated patches and the internal plexiform layer (IPL) was also stained. In contrast to the OB the accessory olfactory bulb stained lightly for CO activity, and did not show a concentric pattern.

RESPONSES OF LATERAL HYPOTHALAMIC NEURONS TO ODOURS BEFORE AND DURING STOMACH DISTENSION IN UNANAESTHETIZED RABBITS

Publisher Summary There is much evidence that the lateral hypothalamic (LH) neurons receive olfactory inputs. Recent neuro-anatomical experiments have demonstrated that the origins of the fibers projecting to the LH neurons exist in several parts of the basal brain, such as the anterior olfactory nucleus, the olfactory tubercle, the amygdale, and the prepyriform cortex. Electro-physiological data also indicate the existence of these olfactory projections. This chapter describes a relationship between the behavior of LH neurons and the condition of the stomach. It discusses the study of the responses to the odors of LH neurons in unanesthetized rabbits. This was done through a preliminary operation performed under anesthesia. After the response patterns of all neurons to eight odors were examined, the rabbits stomach was inflated and any changes in their response patterns were sought. It is still entirely unknown where in the brain, the sensation of smell occurs. However, the finding that responses to odors of neurons in the feeding center become different, depending upon the condition of the stomach, indicates that the odors that are appetite-stimulating during the state of hunger become less and less attractive as the stomach is distended by food intake.

Monoclonal antibody immunohistochemistry of a temporal relationship between axonal elimination of aberrant olfactory nerves and synaptogenesis in the rabbit olfactory bulb during middle embryonic periods

Immunostaining using olfactory nerve- and synaptic vesicle protein-specific monoclonal antibodies revealed their characteristic appearance in the rabbit olfactory bulb during prenatal development. Prior to formation of glomeruli, olfactory nerve fibers extended beyond their target region deep into the bulb zones. Subsequently the aberrant axons decreased in number, and correspondingly, synaptic vesicle protein occurred in the innermost region of the olfactory nerve layer. It is concluded that the lack of synaptogenesis causes axonal elimination of aberrant olfactory nerves. Present results support the hypothesis that supernumerary axons degenerate unless synaptic contacts are secured; the olfactory nerves must arrive at the appropriate terminal zone in the glomeruli.