Peptidergic systems

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. 

Desiderio DM. 1999. Mass spectrometric analysis of neuro-peptidergic systems in the human pituitary and cerebrospinal fluid. J Chrmoatogr B Biomed Sci Appl 731 3. 

Hruby, V. J. Kazmierski, W. M. Pettit, B. M. Al-Obeidi, F., In Molecular Biology of Brain and Endocrine Peptidergic Systems, Chretien,... 

Lamour, Y., Epelbaum, J. (1988). Interactions between cholinergic and peptidergic systems in the cerebral cortex and hippocampus. Prog. Neurobiol. 31 109 8. 

A differential distribution of AChE has been described in the neuropil of the inferior olive of cat (Marani et al., 1977) (Fig. 169), ferret, rabbit (Marani, 1986,), rat (Fig. 166), and the opossum (Martin et al., 1975). These distributions are fairly consistent as to the columnar distribution of the enzyme in the caudal MAO and the rostral DAO, the absence of AChE in the group beta and the presence of AChE in the DC. There are some points of resemblance with the distribution of serotonin in the DAO and the caudal MAO of the cat, but a causal relationship between the presence of AChE and the distribution of certain afferent or efferent (peptidergic) systems of the olive has not been established. 

Brownlee, D.J.A, Fairweather, I., Johnston, C.F. and Shaw, C. (1994) Immunocytochemical demonstration of peptidergic and serotoninergic components in the enteric nervous system of the roundworm, Ascaris suum (Nematoda, Ascaroidea). Parasitology 108, 89-103. 

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]. 

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. 

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. 

Lindholm, A.M., Reuter, M. and Gustafsson, M.K. (1998) The NADPH-diaphorase staining reaction in relation to the aminergic and peptidergic nervous system and the musculature of adult Diphyllobothrium dentriticum. Parasitology 11 7, 283-292. 

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