Perikarya

In contrast to the small transmitter molecules, the neuropeptides are synthesized in the rough endoplasmic reticulum of the neuronal perikarya. They are enclosed in vesicles in the Golgi apparatus. The vesicles travel down to the terminals by axonal transport. 

General structural features of neurons are the perikarya, dendrites and axons 5... 

As axons and dendrites mature, their differences become more apparent [9]. In axons, MTs have a uniform orientation with plus-ends distal to the cell body, but dendrites contain MTs in both orientations. Dendrites and to a lesser extent perikarya contain MAP2, which is excluded from axons at an early stage. Curiously, MAP2 mRNA is one of several mRNAs that are specifically transported... 

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 pathological hallmark of the disease is the presence in the brain of Lafora bodies round, basophilic, PAS-positive intracellular inclusions varying in size from small, dust-like bodies less than 3 nm in diameter to large bodies up to 30 nm in diameter. Lafora bodies are typically seen in neuronal perikarya and processes, not in glial cells, and are more abundant in cerebral cortex, substantia nigra, thalamus, globus pallidus and dentate nucleus. Ultrastructural studies have shown that Lafora bodies consist of two components amorphous electron-dense... 

Aghajanian. G. K... Kuhar, M. J., and Roth, R. H. (1973) Serotonin-containing neuronal perikarya and terminals differential effects of p-chlorophenylalanine. Brain Res., 54 85-101. 

Joo, F Halasz N, Parducz A. Studies on the fine structural localization of zinc-iodide-osmium reaction in the brain I. Some characteristics of localization in the perikarya of identified neurons. J Neurocytol 1973 2 393-405. 

IHC shows CYP19 in neuronal perikarya of quail, rat, monkey, human (Naftolin et al., 1996). 

Receptor autoradiography and immunohistochemistry are used to demonstrate the final location of receptor proteins. In the nervous system, these receptor proteins are synthesized within soma, but are generally transported to dendrites or axons, distant from cell bodies where they are originated. Thus, demonstration of a receptor population by receptor autoradiography or immunohistochemistry is not sufficient to directly discriminate which perikarya synthesize the receptors (Kuhar et al, 1986 Quirion et al., 1993 Chabot et al., 1999). Knowledge of the sequence of the mRNA coding receptor proteins has made the development of nucleic acid probes possible, which can be used in combination with the... 

For instance, H3 receptor density is relatively low in the hypothalamus which contains a high density of histaminergic axons and perikarya. However, the detection of some H3 receptors at the level of the tuberomammillary nuclei possibly indicates the existence of autoreceptors at the level of histamine perikarya or dendrites [62-66],... 

Subchronic oral administration of lithium causes a time-dependent increase in the substance P level in the striatum, which is prevented by coadministration of haloperidol. In PC 12 pheochromocytoma cells, lithium dramatically increases the intracellular levels of the neuropeptide neurotensin and the mRNA encoding it. An extensive overlap between specific and high-affinity neurotensin binding sites and dopamine perikarya and dendrites has been shown to occur in the mesocorticolimbic and nigrostriatal projection systems. Consistent with this observation are the results of observations showing that cocaine, an indirect sympathomimetic agent that enhances the extrapyramidal dopaminergic activity, increases dramatically the striatal content of neurotensin-like immunoreactivity. 

Orexins (also known as hypocretins) and presynaptic receptors activated by orex-ins were first described in 1998 (Figure 1). Orexin-A (hypocretin-1) and orexin-B (hypocretin-2) consist of 33 and 28 amino acid residues, respectively, and are derived from a common precursor molecule (prepro-orexin). They act on two receptors, OXi and OX2. Orexinergic neurones have their perikarya in the lateral and posterior part of the hypothalamus and project to many parts of the brain, including the cerebral cortex, thalamus, limbic system, locus coeruleus and raphe nuclei, and to the spinal cord. Orexin-like immunoreactive neurones also occur in the small intestine (for review, see Smart and Jerman 2002). 

The terminology in the literature is confusing. Terms used for the outer (nucleate) zone include syncytial layer, surface layer, distal cytoplasm, tegument and for the inner (nucleated) zone perikarya, proximal layer, tegumental cells, cytons, perinuclear cytoplasm. Bearing in mind that descriptive terms are more likely to be remembered and used correctly than non-descriptive words, the terms distal cytoplasm and proximal cytoplasm, which are well established in the literature, are used in this text, for these zones. The term tegumental cytons is used for the basic cells which make up the syncytial epithelium (Fig. 2.1). 

Kalivas PW, Duffy P (1993) Time course of extracellular dopamine and behavioral sensitization to cocaine. II. Dopamine perikarya. J Neurosci 73 276-284. 

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