Serotonin cells

COMMENT We feel that it is due to the formation of 5,6-DHT in the eortex. These cells are indeed innervated by serotonin cells and, as a matter of fact, we have an experiment that is being published in Brain Research where we show that if we injeet 5,6-DHT into the ventricles, we ean produce exactly the same type of degeneration in the pyramidal cells, due to the formation of the 5,6 from the 5-hydroxytryptamine. We are exploring the possibility of it being another catecholamine in addition to dopamine, so I think both of those may be helpful in answering your question. 

Figure 3. Sketch of DDC-expressing neurons in the Drosophila larval CNS. The CNS consists of brain lobes and a segmented ventral ganglion. Filled circles represent dopamine cells open circles represent serotonin cells grayed circles represent DDC cells that contain no detectable tyrosine hydroxylase or serotonin immunoreactivity, indicating that these cells may produce neither transmitter (Lundell and Hirsh, 1994). M, medial dopamine neurons VL, ventrolateral serotonin neurons DL, dorsolateral dopamine neurons. The hatched rectangle shows the region of the ventral ganglion that is shown in Figures 4 and 6.

The majority of DDC-expressing cells in the brain lobes are dopamine cells. Most of these dopamine cells have axons that project into a common axonal fiber extending anteriomedially within the brain lobe and then separating into finer fibers that cross between the lobes. The dopamine cells occur in small clusters of two to six cells, which suggests that these cells might share common lineages. The serotonin cells within the lobes are also found in pairs, and each pair projects axons into closely associated tracts. The pathways of the serotonin tracts often parallel those of the dopamine cells but are distinct (Lundell and Hirsh, 1994). 

Figure 4 shows confocal images of the staining pattern for DDC (Fig. 4A), serotonin (Fig. 4B), and TH (Fig. 4C) in the segmental ventral ganglion of the CNS from third instar larvae. Panels B and C are the same CNS double stained with serotonin and TH. The DDC-expressing cells can be categorized into a set of paired ventral lateral serotonin cells (Fig. 4A,B labeled VL in 4A), and two morphologically distinct types of dopamine cells, the medial dopamine cells (Fig. 4A,C labeled M) and the dorsal-lateral dopamine cells (Fig. 4A,C labeled DL). Figure 4 demonstrates clearly that individual DDC cells synthesize either serotonin or dopamine, but not both. One additional set of cells shows TH immunoreactivity in the ventral ganglion. These six large vacuolated cells are located more laterally than any other DDC cells (Fig. 4C, unlabeled short arrows). It is likely that the immunoreactivity in these cells results from a non-specific cross-reaction, since these cells are not...

The axonal projections from the DDC-expressing cells in the ventral ganglion also show tendencies to follow common pathways. The projections from the ventral lateral serotonin cells extend medially to fuse with axons projecting from the contralateral serotonin cells. At the midline, this projection is met by an axonal projection from the medial dopamine cell. 

The second cell-specific regulatory element within the distal enhancer is named SER. Loss of this element, which is at the extreme distal edge of the enhancer, leads to a selective loss of DDC expression in the ventral lateral serotonin cells (Johnson et al., 1989 Lundell and Hirsh, 1992) (Fig. 6C). This element has been delimited to about 40 bp and shows unexpected complexity, consisting of two functionally redundant elements. These two subelements, SERl and SERr, are each sufficient to allow normal DDC expression in the ventral lateral serotonin neurons if the other is deleted. In spite of this functional similarity, no sequence similarity is apparent between the two regions. The region of conservation between D. melanogaster and D. virilis is limited to SERl. 

Figure 7.4. Summary of the site of action of mirtazepine (NaSSA). The inhibitory 2 adrenoceptors facilitate the release of both noradrenaline and serotonin (via the heteroceptor on the 5-HT neuron). This is further enhanced by the receptor on the serotonin cell body. Thus mirtazepine (and to a lesser extent mianserin) enhance both noradrenergic and serotonergic...

Hydroxytryptamine (serotonin) Cell bodies in midbrain and pons project to all levels 5-HT1A LSD Metergoline, spiperone Inhibitory t K+ conductance, CAMP... 

Adell A, Celada P, Artigas F. The role of 5-HT1B receptors in the regulation of serotonin cell firing and release in the rat brain. J Neurochem 2001 79 172-182. 

B4 serotonin cells B4 B9 serotonin cells B9 Barrington s nucleus Bar basal nucleus (Meynert) B basilar artery bas basolateral amygdaloid nucleus BL basolateral amygdaloid nucleus, anterior part BLA... 

B basal nucleus (Meynert) 21-26,28-32, 84-89, 96-104 B4 B4 serotonin cells 66-70 B9 B9 serotonin cells 46-51... 

Cho T, Chan W, Cutz E. Distribution and frequency of neuroepithelial bodies in postnatal rabbit lung quantitative study with monoclonal antibody against serotonin. Cell Tissue Res 1989 255 353-362. 

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