Neurons unipolar

Figure 1.14 (a) Basic structure of a neurone. A motor neurone is shown, but the basic structure of all the neurones is the same. Dendrites transfer information from other nerves to the neurone, while the axon transfers information from the neurone to other neurones or tissues. The axon is particularly long in motor neurones (Chapter 14). (b) Structures of unipolar, bipolar and multipolar neurones. Unipolar neurones transfer information from tissues or organs to the brain. Multipolar neurones are the most abundant in the nervous system. 

Multipolar neurons have many processes and serve principally as motor neurons. Motor neurons, efferent because they conduct impulses away from the central nervous system (the brain and spinal cord) regulate the function of muscles and glands. Afferent neural pathways that send signals to the (CNS) are generally composed of unipolar neurons. Unipolar neurons also serve as sensory neurons— their filamentous dendritic processes exposed and elaborated into or connected to sensory receptor cells. Intemeurons are neurons that connect neurons along a neural pathway. 

Furlong RA, Ho L, Rubinsztein JS, Walsh C, Paykel ES, Rubinsztein DC (1998) No association of the tryptophan hydroxylase gene with bipolar affective disorder, unipolar affective disorder, or suicidal behaviour in major affective disorder. Am J Med Genet 81 245-247 Gaiter D, Unsicker K (2000a) Brain-derived neurotrophic factor and trkB are essential for cAMP-mediated induction of the serotonergic neuronal phenotype. J Neurosci Res 61 295-301... 

There is an emerging literature in MRS in adults with BD, with reports of decreases in dorsolateral prefrontal cortex of neuronal marker NAA (Winsberg et al., 2000) and abnormalities in phopholipid metabolism (Kato et ah, 1995, 1998 Hamakawa et ah, 1999). There is preliminary work to suggest that cortical GABA levels and glutamate turnover are decreased in unipolar depression in adults, but these abnormalities may not be present in bipolar depression (Sanacora et al., 1999, Mason et al., 2000). 

Nikolaus, S., Larisch, R., Ben, M., Vosberg, H., and Muller-Gartner, H.W. (2000) Diffuse cortical reduction of neuronal activity in unipolar major depression a retrospective analysis of 337 patients and 321 controls. Nucl Med Commun 21 1119—1125. 

Zhang X, Gainetdinov RR, Beaulieu JM, et al. Loss-of-function mutation in tryptophan hydroxylase-2 identified in unipolar major depression. Neuron 2005 45(1) 11-16. 

In the scolex ganglion of the tetraphyllid Pelichnobothrium speciosum, where unipolar and multipolar neurones are found, the nerve cell processes have been reported as forming tight junctions which cannot be interpreted as synaptic contacts 260) this anomalous observation clearly requires confirmation. 

Pseudo-unipolar neurons have a single process that arises from the cell body and divides into two branches. One of these branches projects to the periphery, while the other projects to the CNS. Each branch has the structural and functional characteristics of an axon. Information collected from the terminals of the peripheral branch is transmitted to the CNS via the terminals of the other branch. Unipolar neurons are relatively... 

Unipolar Neuron (Formally Called Pseudounipolar Neurons)... 

Actually, unipolar neurons have two axons rather than an axon and dendrite (Figure 14.3). Mostintemeurons, which form all the neural wiring within the CNS, are of this type. Examples include spinal ganglia, most cranial nerve sensory ganglia, and the trigeminal mesencephalic nucleus. Dorsal root ganglia cells extend one axon centrally toward the spinal cord, and the other axon toward the skin or muscle. 

Unipolar, bipolar, and multipolai neurons ai e best described by... 

Figure 14.3. Drawing of a unipolar neuron (modified with permission from http //homepage.psy.utexas.edu/homepage/class/Psy332/Sahnas/ Cells/sensoryneuron.gif).

Fig. 2. Diagrams of the cerebellar circuit. Inhibitory neurons are indicated in black. A. Main circuit. B. Cortical interneurons and recurrent pathways. Abbreviations B = basket cell cf = climbing fiber G = Golgi cell GR = granule cell 10 = inferior olive mf = mossy fiber nc = nucleocortical axons no = nucleo-olivary axons pcc = recurrent Purkinje cell axon collaterals P cell = Purkinje cell PCN = precerebellar nuclei pf = parallel fiber pi = pinceau of basket cell axons S = stellate cell UBC = unipolar brush cell I = extracerebellar mossy fiber 2 = nucleo-cortical mossy fiber 3 = mossy fiber collateral of uni-polar brush cell.

Fig. 69. A. Monoclonal antibody Rat-302 recognizes a subset of neurons, later identified as unipolar brush cells, restricted to the granular layer of the flocculus and the vermis of rat cerebellum (arrows), whereas in other areas of the cerebellum no positive cells are found. B. In contrast, antibody Rat-303 recognizes Golgi-II cells in the granular layer (g) in the entire cerebellum. C. Rat-302 also recognizes Purkinje cells outside the caudal vermis and the flocculus. D. Rat-302 positive cells in the vermis. E and F. Unipolar brush cells recognized by Rat-302 have a round cell body and short dendrites ending in a spray of appendages (arrows), g, granular layer m, molecular layer p, Purkinje cell layer. Scale bars 500 fim in A and B, 50 /rm in C and D. 10 /rm in E and F. Hockfield (1987).

Harris J, Moreno S, Shaw G, Mugnaini E (1993) Unusual neurofilament composition in cerebellar unipolar brush neurons. J. Neurocytol, 22, 663-681. 

Mugnaini E, Floris A (1994) The unipolar brush cell A neglected neuron of the mammalian cerebellar cortex. J. Comp. Neurol. 339, 174-180. 

Patients with unipolar depression are effectively treated with drugs, such as chlo-rimipramine and more recently fluoxetine, which are known to block neuronal uptake of serotonin. In addition, giving 5-hydroxy tryptophan (a precursor of serotonin) either alone or in combination with chlorimipramine seems to benefit these patients. 

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