Neuronal somata

The disease models can be grouped into four primary categories (Fig. 20.1). (1) Motor neuron diseases, in which the death of motor neuron somata in the spinal cord results in denervation of the muscles, progressive flaccid paralysis, and usually premature death. In humans, examples of such diseases would include amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). (2) Peripheral neuropathies, in which axonal integrity or conduction is not maintained, resulting in axon degeneration and impaired connectivity of the nervous system and the musculature. 

In the single electron microscopic immunocytochemical study thus far carried out with these antibodies (242), 5-HT7 receptors were described as located in neuronal somata and dendrites, fine unmyelinated axons, and axon terminals of the mouse suprachiasmatic nucleus (SCN). After double immunoperoxidase (5-HT7) and immunogold labeling, some of these SCN soma-dendrites and axon terminals could be shown to be GABA, vasoactive intestical polypeptide (VIP), or vasopressin (VP) immunoreactive. Astrocytes in the SCN, characterized by their numerous filaments, were also reported as immunopositive for 5-HT7 receptors. 

SNX-111 blocks N-type calcium channels, which are located throughout the CNS on neuronal somata, dendrites, dendritic spines, and axon terminals, where they play a major role in the regulation of the neurotransmitters associated with pain transmission and stroke. The drive is to discover an orally active, selective, small-molecule modulator of N-type calcium channels to overcome the disadvantages of administration of SNX-111. 

Sofroniew, M. V. and Isacson, O., Distribution of degeneration of cholinergic neurons in the septum following axotomy in different portions of the fimbria-fomix a correlation between degree of cell loss and proximity of neuronal somata to the lesion, J. Chem. Neuroanat., 1, 327, 1988. 

Ribak CE, Vaughn JE, Saito K (1978) Immunocytochemical localization of glutamic add decarboxylase in neuronal somata following colchicine inhibition of axonal transport. Brain Res 140 315-332. 

Responses to GABA and Other Neurotransmitters in Insect Central Neuronal Somata In Vitro... 

Figure 3. Currents recorded from isolated locust thoracic neuronal somata voltage-clamped by a conventional single-electrode method, a) Application of 1 sec pressure pulses of 10M GABA to a neuron clamped at a series of different holding potentials shows the direction and voltage-dependence of the current underlying the change in membrane potential seen in all cells in response to GABA or muscimol.

Figure 4. Muscimol and GABA evoked a biphasic response in some Locusta neuronal somata.

Figure 5. Picrotoxin blocked the GABA- and muscimol-evoked responses in the locust thoracic neuronal somata.

Fig. 6. The role of peripheral neuron somata in sensory axon guidance in the wing disc of Drosophila. (A-C) The sequence of axon growth from sensory neurons in the wing disc. (A) 6 h after pupariation (AP). (B)12 h AP. (C) 30 h AP. Axons from distal neurons contact the somata of more proximal neurons (e.g. L3-2 axon contacts L3-v soma) en route to the base of the wing disc. For example, arrow in (B) indicates where the axon of L3-2 contacts the L3-v soma. Camera lucida drawings of embryos stained using anti-HRP immunohistochemistry. Scale bars (A) 85/

Efferent motor axons in the grasshopper embryo are apparently guided into the limb bud by contact with the peripheral sensory Cxi neuron somata... 

Whitington, 1989). Neuronal somata may also function as guidepost cells for efferent axons in the leech. Braun and Stent (1989a) have shown that motor axons contact peripheral neuron somata during outgrowth and that the rate of growth of the motor axons transiently decreases when they contact these somata. 

The axons that pioneer the posterior transverse commissure in the Drosophila embryo have been reported to associate closely with the most anterior of the midline VUM neuronal somata (Klambt et al., 1991), and it has been suggested that contact with this soma may be important in guiding these axons across the midline (Fig. 8). 

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