Peptidergic neurones

Moragues, N., Ciofi, P., Lafon, P., Tramu, G., Garret, M. (2003). GABAa receptor epsilon subunit expression in identified peptidergic neurons of the rat hypothalamus. Brain Res. 967, 285-9. 

With this in mind, the search for molecular markers that define populations of neurons in areas important for arousal is clearly warranted. In this chapter we describe the identification of four peptidergic systems that modulate different aspects of the sleep-wakefulness cycle. The success of this strategy demonstrates the need for new markers of neuronal cell types, which may define populations of neurons critical for our understanding of cortical activity and sleep. 

The study of peptidergic neurons requires a number of special tools 328... 

The study of peptidergic neurons requires a number of special tools. These tools include methods to detect the neuropeptides both in cells and after release, the enzymes specific to their biosynthesis and their cognate receptors. Since the actions of peptides require secretion, measurements of cell content (e.g. immunostaining) can be deceptive, with a decrease in content reflecting increased release. 

Helke, C. J., Krause, J. E., Mantyh, P. W., Couture, R. and Bannon, M. J. Diversity in mammalian tachykinin peptidergic neurons multiple peptides, receptors, and regulatory mechanisms. FASEB J 4 1606-1615,1990. 

In order to influence mast-cell function, peptides must be made available at sites very near to tissue mast cells. One means of accomplishing this is by specific peptidergic innervation. This would not necessarily require a classical synaptic morphology, but only the termination of nerves within the vicinity of mast cells [1,3]. Modulation of mast-cell secretion by peptides of neural origin is particularly attractive, for it would allow for a restricted, localized expression of peptide action in specific target tissues because of the selective distribution of each peptide within particular neurones. Moreover, this could be further modified and restricted by differing mast cell specificities. (Heterogeneity of mast cell responsiveness to peptide stimulation has been well documented [52, 53 ].) The result would permit a well-localized tissue response without systemic manifestation [3]. 

Substance P, calcitonin-gene-related peptide (CGRP), and neurokinin A have been identified by immunocytochemistry in primary sensory neurones and in cutaneous sensory nerve terminals and these are often in close proximity to mast cells [54, 56], For example, in Lewis rats that were infected with the parasitic larvae of Nippostrongylis brasiliensis in order to induce a proliferation of mucosal mast cells, nearly two-thirds of the lamina propria mast cells were in intimate contact with peptidergic nerves containing SP and CGRP, while an additional 20% of the mast cells were within 2 gm [54], All three peptides are... 

There are more than 10 billion neurons that make up the human nervous system, and they interact with one another through neurotransmitters. Acetylcholine, a number of biogenic amines (norepinephrine, dopamine, serotonin, and in all likelihood, histamine and norepinephrine), certain amino acids and peptides, and adenosine are neurotransmitters in the central nervous system. Amino acid neurotransmitters are glutamic and aspartic acids that excite postsynaptic membrane receptors of several neurons as well as y-aminobutyric acid (GABA) and glycine, which are inhibitory neurotransmitters. Endorphins, enkephalins, and substance P are considered peptidergic transmitters. There are many compounds that imitate the action of these neurotransmitters. 

Wotjak CT, Ganster J, Kohl G, Holsboer F, Landgraf R, Engelmann M (1998) Dissociated central and peripheral release of vasopressin, but not oxytocin, in response to repeated swim stress new insights into the secretory capacities of peptidergic neurons. Neuroscience 85 1209-1222... 

Neurotrophic factors responsible for neuronal survival, dendritic proliferation, and the activation of the different neurotransmission systems are present in the central nervous system [CNS). The most well-known one is the NGF, a peptidergic complex of 140 kd and with a sedimentation coefficient of 7s. NGF has three subunits, a, p, and y. Subunit p is the active part of the molecule. Other neurotrophic factors [F. ffefti 1994) include 1) brain-derived neurotrophic factor [BDNF), 2) neurotrophin 3, 3) neurotrophin 4/5, and 4) ciliary neurotrophic factor. 

Kupfermann, Irving. 1991. "Hypothalamus and Limbic System Peptidergic Neurons, Homeostasis, and Emotional Behavior." In Principles of Neural Science, edited by Eric R- Kandel, James H. Schwartz, and Thomas M. Jessell. 3d ed. New York Elsevier. 

The role of peptidergic neurons is not so clear. Capsaicin, the hot chile pepper chemical that evokes release of peptide transmitters from several types of sensory nerves, has been shown to reproduce some of the signs of bronchial hyperreactivity in animal and human experiments. These findings led to the proposal that sensitization of afferent nerve endings played a major role in chronic airway hyperreactivity. However, peptide transmitter antagonists have not been able to prevent bronchoconstriction in several models. Clearly, much remains to be learned about airway pharmacology. 

An elegant demonstration that the larval/adult transformation, resulting in sexual differentiation, is, in fact, associated with a neurosecretory mechanism has been made by Gustafsson and co-workers (207, 278, 280, 281,283). They showed that a clear activation of the peptidergic neurones took place when plerocercoid larvae of Diphyllobothrium dendriticum were transferred from the poikilothermic intermediate fish host to the final homeothermic bird host. The effect could also be reproduced by cultivating... 

Gustafsson, M. K. S. Wikgren, M. C. (1981a). Peptidergic and aminergic neurons in adult Diphyllobothrium dendriticum Nitzsch, 1824 (Cestoda, Pseudophyllidea). Zeitschrift fur Parasitenkunde, 64 121-34. 

Le Moine C, Bloch B (1996) Expression of the D3 dopamine receptor in peptidergic neurons of the nucleus accumbens comparison with the D1 and D2 dopamine receptors. Neuroscience 73 131-143. 

Lechner J, Leah JD, Zimmerman M (1993) Brainstem peptidergic neurons projecting to the medial and lateral thalamus and zona incerta in the rat. Brain Res 603 47-56. 

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