Neurons catecholamine-containing

Budnik, V., and White, K. (1988). Catecholamine containing neurons in Drosophila melanogaster distribution and development. J. Comp. Neurol. 268 400-413. 

The concentration of catecholamines within nerve terminals remains relatively constant. Despite the marked fluctuations in the activity of catecholamine-containing neurons, efficient regulatory mechanisms modulate the rate of synthesis of catecholamines [ 11 ]. A long-term process affecting catecholamine synthesis involves alterations in the amounts of TH and DBH present in nerve terminals. When sympathetic neuronal activity is increased for a prolonged period of time, the amounts of mRNA coding for TH and DBH are increased in the neuronal perikarya. DDC does not appear to be modulated by this process. The newly synthesized enzyme molecules are then transported down the axon to the nerve terminals. 

The action of catecholamines released at the synapse is modulated by diffusion and reuptake into presynaptic nerve terminals. Catecholamines diffuse from the site of release, interact with receptors and are transported back into the nerve terminal. Some of the catecholamine molecules may be catabolized by MAO and COMT. The cate-cholamine-reuptake process was originally described by Axelrod [18]. He observed that, when radioactive norepinephrine was injected intravenously, it accumulated in tissues in direct proportion to the density of the sympathetic innervation in the tissue. The amine taken up into the tissues was protected from catabolic degradation, and studies of the subcellular distribution of catecholamines showed that they were localized to synaptic vesicles. Ablation of the sympathetic input to organs abolished the ability of vesicles to accumulate and store radioactive norepinephrine. Subsequent studies demonstrated that this Na+- and Cl -dependent uptake process is a characteristic feature of catecholamine-containing neurons in both the periphery and the brain (Table 12-2). 

The neuronal membrane norepinephrine transporter (NET), the dopamine transporter (DAT) and the vesicular membrane transporter (VMAT-2), which is the same in all catecholamine-containing neurons, have similar numbers of predicted transmembrane segments. They have different numbers of amino acids, pharmacological properties and chromosomal localizations. 

The linkage of uptake to the Na+ gradient may be of physiological significance since transport temporarily ceases at the time of depolarization-induced release of catecholamines. The transport of catecholamines can be inhibited selectively by such drugs as tricyclic antidepressants and cocaine. In addition, a variety of phenylethyl-amines, such as amphetamine, are substrates for carrier thus, they can be concentrated within catecholamine-containing neurons and can compete with the catecholamines for transport. 

Besson, M. J., Cheramy, A., and Glowinski, J. (1969) Effects of amphetamine and desmethyl-imipramine on amine synthesis and release in central catecholamine containing neurons. Eur. J. Pharmacol., 7 111-114. 

In contrast, the content of norepinephrine is substantially lower than the content of dopamine (28). Catecholamine-containing neurons do not innervate the parenchymal cells of the bovine parathyroid gland only an occasional norepinephrine-containing neuron terminating upon a blood vessel is demonstrated by fluorescence histochemistry (22). 

Tillet Y, Thibault J (1989) Catecholamine-containing neurons in the sheep brainstem and diencephalon immunohistochemical study with tyrosine hydroxylase (TH) and dopamine-P-hydroxylase (DBH) antibodies. J Comp Neurol 290 69—104. 

Hydroxydopamine (6-OHDA). Administration of 6-OHDA destroys catecholamine-containing neurons and therefore decreases norepinephrine brain levels. In turn, REM sleep is increased. 

Catechol-0-methyltransferase (COMT) is responsible for the second major pathway of catecholamine metabolism, catalyzing 0-methylation of dopamine to methoxytyramine, norepinephrine to normetanephrine, and epinephrine to metanephrine. COMT is not present in monoamine-producing neurons, which contain exclusively MAO, but is present along with MAO in most extraneuronal tissue. The membrane-bound isoform of COMT, which has high affinity for catecholamines, is especially abundant in adrenal chromaffin cells. As a result of the preceding and other differences in the expression of metabolizing enzymes, catecholamines produced at neuronal and adrenal medullary locations follow different neuronal and extraneuronal pathways of metabolism (Figure 29-5). 

Chu N-S, Bloom FE (1974) The catecholamine-containing neurons in the cat dorsolateral pontine tegmentum distribution of the cell bodies and some axonal projections. Brain Res, 66, 1-21. 

Frontali, N. (1968) Histochemical localisation of catecholamine containing neurones in the cockroach brain. J. Insect Physiol., 14.881-886. 

OHDA accumulates in catecholamine-containing neurons and exhibits selective toxicity towards them. 6-OHDA is often administered in-trastriatally to rats to induce degeneration of nigrostriatal neurons (Berger et al., 1991 Ichitani... 

Reserpine exerts its antihypertensive action by virtue of its adrenergic neutronal blockade consequent to depletion of the catecholamines-containing granudles of the postganglionic sympathetic neuron. It, however, depletes both brain catecholamines and seritonins. 

The presence of the catecholamines in the central nervous system (CNS) was first demonstrated in 1946 [119]. Several years later, dopamine (DA) was shown to be present in the brain [120,121] though unevenly distributed [122), whilst more recently, catecholamine-containing neurone sterns in the CNS have been mapped out in considerable detail [123]. 

Pilowsky PM, Jiang C, Lipsky J. An intracellular study of respiratory neurons in the rostral ventrolateral medulla of the rat and their relationship to catecholamine-containing neurons. J Comp Neurol 1990 301 604—617. 

Until quite recently the only adrenergic neurons which had been studied were those of the peripheral sympathetic nervous system. However, it is now clear that adrenergic neurons also exist in the CNS. Extensive studies of the distribution of catecholamine-containing neurons have been made using the fluorescence histo-... 

All the available evidence suggests that catecholamine-containing neurons of the CNS are similar in virtually all respects to peripheral sympathetic neurons. They appear to share the same biosynthetic machinery, and utilize the same catabolic pathways. 

Crow, T. J, (1972) Catecholamine containing neurones and electrical self-stimulation I. a review of some data. Psychol. Med., 2, 414. 

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