Olfactory bulb

The effects of VIP and PACAP are mediated by three GPCR subtypes, VIP, VIP2, and PACAP receptor, coupled to the activation of adenjiate cyclase (54). The VIP subtype is localized ia the lung, Hver, and iatestiae, and the cortex, hippocampus, and olfactory bulb ia the CNS. The VIP2 receptor is most abundant ia the CNS, ia particular ia the thalamus, hippocampus, hypothalamus, and suprachiasmatic nucleus. PACAP receptors have a wide distribution ia the CNS with highest levels ia the olfactory bulb, the dentate gyms, and the cerebellum (84). The receptor is also present ia the pituitary. The VIP and PACAP receptors have been cloned. 

A high concentration of DOPs is found in the olfactory bulb, the neocortex, caudate putamen, and in the spinal cord, but they are also present in the gastrointestinal tract and other peripheral tissues. The functional roles of DOP are less clearly established than for MOP they may have a role in analgesia, gastrointestinal motility, mood and behaviour as well as in cardiovascular regulation [2]. 

Alternate ways to interfere with the orexin system may be via inhibition of dipeptidyl peptidases or proteolysis-resistant peptide analogs as shown for other peptides. This could prolong and boost orexinergic signaling. OX-A but not OX-B can enters the brain by simple diffusion via the blood-brain barrier. Abundance of orexins and their receptors in the olfactory bulb and throughout all parts of the central olfactory system may offer transnasal routes for drug application. 

Localization CNS Hippocampus (CA1, CA3, DG), septum, amygdala, raphe nuclei CNS Striatum, hippocampus (CA1), substantia nigra, globus pallidus, superior colliculi, spinal cord, raphe nuclei CNS like 5-HT1B but at lower densities. CNS Caudate putamen, parietal cortex, fronto-parietal motor cortex, olfactory tubercle, amygdala CNS Cortex, Thalamus, olfactory bulb (rat), claustrum (g-pig), hippocampus (CA3), spinal cord. 

Localization CNS Cortex, hippocampus, striatum, olfactory bulb, spinal cord CA/S not present in adult. CNS Choroid plexus, medulla, pons, striatum, hippocampus (CA1, CA3), hypothalamus, spinal cord CNS Striatum, hippocampus (CA1), substantia nigra, globus pal-lidus. CNS Striatum, brainstem, thalamus, hippocampus, olfactory bulb, substantia nigra... 

Localisation CA/S Hippocampus (CA1, CA3, DG), cortex, cerebellum (granular layer), olfactory bulb, habenula, spinal cord CA/S Caudate putamen, olfactory tubercle, nucleus accumbens, cortex, hippocampus (CA1, CA3, DG) CA/S Hippocampus (CA1, CA2), hypothalamus, thalamus, superior colliculus, raphe nuclei... 

Many brain areas are innervated by neurons projecting from both the locus coeruleus and the lateral tegmental system but there are exceptions (Fig. 8.3). The frontal cortex, hippocampus and olfactory bulb seem to be innervated entirely by neurons with cell bodies in the locus coeruleus whereas most hypothalamic nuclei are innervated almost exclusively by neurons projecting from the lateral tegmental system. The paraventricular nucleus (and possibly the suprachiasmatic nucleus, also) is an exception and receives an innervation from both systems. 

Malick, J.B. Pharmacological antagonism of mouse-killing behavior in the olfactory bulb lesion-induced killer rat. Aggressive Behav 2 123-130,... 

McLean, J.H., and Shipley, M.T. Serotonergic afferents to the rat olfactory bulb 1. Origins and laminar specificity of serotonergic inputs in the adult rat. J Neurosci 7 3016-3028, 1987. 

Central/Tertiary structures The fish olfactory bulb is a fourlayered structure much as in higher vertebrates. Within the 2nd layer, the first synapse for olfactory input is on the dendrites of the mitral cells (MC). About 1000 ORN axons converge on one MC, a ratio similar to mammals. The MC output, from cells at various levels, leads into several glomeruli and receives (inhibitory) input from granule cells. The latter also innervate a distinct cell type in the MC layer of teleosts — the ruffed cells (RC), with which they have reciprocal synapses [Fig. 2.18(a)] both relay cells send ascending fibres to forebrain centres (Kosaka and Hama, 1982). The RC are unlike the MC since they are not stimulated by the ORNs directly. Their interactions (Chap. 5) may contribute to the processing of pheromonal stimuli (Zippel, 2000). The main bulbar pathways project to several nuclei in the forebrain via two ipsilateral tracts, the lateral and medial [Fig. 2.18(b)], the latter mediates sexual behaviour and the former probably other behaviours (Hara,... 

An extra-bulbar olfactory pathway (EBOP) is present in teleosts and in some non-teleost genera. Olfactory fibres run within the medial forebrain bundle, and can be traced (by SBA lectin binding) beyond the olfactory bulb into areas such as the ventral telencephalon, and/or the preoptic nucleus (Hofmann and Meyer, 1995). The projection of the EBOP fibres is similar in the sturgeon, but in other non-teleosts the primary olfactory fibres reach diencephalic target nuclei. 

In its central projections the vomeronasal pathway, distinguished by a unique lectin-affinity, ascends to an accessory olfactory bulb, while dorsal and ventral pathways supply the dorsal and ventral regions of the main olfactory bulb (Saito and Taniguchi, 2000). The AOS (but not the MOS) of salamanders displays considerable diversity in the... 

Fig. 4.4(a) Development of the N. terminalis in mammals and relationship to Vomeronasalis system (i) f = filia olfactoria (ii) induction of olfactory bulb and (iii) to (iv) separation of main/accessory systems (v,o) — from t, Nt system g, Nt ganglion + p/c, peripheral and t, central fibres (from Oelschlaeger, 1989). 

Alonso J., Arevalo R., Garciaojeda E., Porteros A., et al. (1995). NADPH-diaphorase active and calbindin d-28k-immunoreactive neurons and fibers in the olfactory-bulb of the hedgehog (Erinaceus europaeus). J Comp Neurol 351, 307-327. 

Andres K. (1970). Anatomy and ultrastructure of the olfactory bulb in fish, amphibia, reptiles, birds and mammals. In Taste and Smell in Vertebrates (Wolstenholme G. and Knight J., eds.). J A Churchill, London, pp. 177-193. 

Barber P.C. and Raisman G. (1974). An autoradiographic investigation of the projection of the vomeronasal organ to the accessory olfactory bulb in the mouse. Brain Res 81, 21-30. 

Beltramino C. and Taleisnik S. (1983). Release of LH in the female rat by olfactory stimuli. Effect of the removal of the vomeronasal organs or lesioning of the accessory olfactory bulbs. Neuroendocrinology 36, 53-58. 

Brennan P.A., Kendrick K. and Keveme E.B. (1995). Neurotransmitter release in the accessory olfactory bulb during and after the formation of an olfactory memory in mice. Neuroscience 69, 1075-1086. 

Brennan P., Schellinck H. and Keverne E.B. (1999). Patterns of expression of the immediate-early gene egr-1 in the accessory olfactory bulb of female mice exposed to pheromonal constituents of male urine. Neurosci 90, 1463-1470. 

Brunjes P.C., Jazaeri A. and Sutherland M.J. (1992). Olfactory bulb organization and development in Monodelphis domestica, the Grey Short-tailed Opossum. J Comp Neurol 320, 544-554. 

Brunjes P.C. and Kishore R. (1998). Unilateral naris closure and the rat accessory olfactory bulb. Chem Senses 23, 717-720. 

Burton P.R. (1990). Vomeronasal and olfactory nerves of adult and larval bullfrogs II. Axon terminations and synaptic contracts in the accessory olfactory bulb. J Comp Neurol 292, 624-637. 

Cooper A. (1974). Effects of accessory olfactory bulb lesions on the sex behavior of male mice. Bull Psychonom Sci 1, 419-420. 

Corotto R, Henegar J. and Maruniak J. (1994). Odor deprivation leads to reduced neurogenesis and reduced neuronal survival in the olfactory bulb of the adult mouse. Neuroscience 61, 739-744. 

Davis B.J., Macrides F., Youngs W.M., Schneider S.P., et al. (1978). Efferents and centrifugal afferents of the main and accessory olfactory bulbs in the hamster. Brain Res Bull 3, 59-72. 

De Olmos J.S., Hardy H. and Heimer L. (1978). The afferent connections in the main and accessory olfactory bulb formations in the rat an experimental HRP study. J Comp Neurol 181, 213-244. 

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