Central nervous system communication

Neurons in the central nervous system communicate by chemical transmission. Of relevance to the present discussion are monoamine neurons that release dopamine, norepinephrine, or serotonin as one of their transmitters in response to an action potential. Reuptake transporter proteins embedded in the neuronal plasma membrane then clear the synapse of monoamines, typically taking up 70-80%) of the released transmitter. This reuptake is thought to be the major termination mechanism for the monoamine chemical signaling process. 

Johnston R.E. (1985). Olfactory and vomeronasal mechanisms of communication. In Taste, Olfaction and the Central Nervous System (Pfaff D.W., eds.). Rockefeller University Press, N.Y. 

Partti-Pellinen et al. (1996) used a cross-sectional, self-administered questionnaire to assess the eye, respiratory tract, and central nervous system symptoms experienced by adults in a slightly polluted and a reference community. In the polluted community the mean annual TRS concentrations were 2-3 g/m3, the 24-hour average concentrations varied between 0-56 g/m3, and the maximum 1-hour concentration was 155 g/m3 there was no TRS detected in the reference community. In the polluted community, the sulfur dioxide annual mean concentration was 1 g/m3, the 24-hour average concentrations varied... 

The billions of individual neurones within the nervous system communicate with each other and with the target tissues via chemical neurotransmitters. There is a bewildering array of chemicals which act as neurotransmitters or neuromodulators in peripheral or central nervous systems. These compounds fall into four major groups and some examples are shown in Table 4.3. 

Vallejo YE, Buisson B, Bertrand D, Green WN (2005) Chronic nicotine exposure upregulates nicotinic receptors by a novel mechanism. J Neurosci 25 5563-5572 Vemino S, Amador M, Luetje CW, Patrick J, Dani JA (1992) Calcium modulation and high calcium permeability of neuronal nicotinic acetylcholine receptors. Neuron 8 127-134 Vizi ES, Lendvai B (1999) Modulatory role of presynaptic nicotinic receptors in synaptic and non-synaptic chemical communication in the central nervous system. Brain Res Brain Res Rev 30 219-235... 

It may come as a surprise that CO is synthesized by the human body and has roles in human metabolism. Specifically, an enzyme that degrades heme, a constituent of hemoglobin, our oxygen-transporting protein, makes CO, which is a neurotransmitter. Much more about neurotransmitters follows in chapter 21 when we talk about the central nervous system. For the present, just understand that specialized cells known as neurons are the conduits for communication in the nervous system. Neurotransmitters are small molecules that relay information from one neuron to another. Neurotransmitter CO is made, functions, and is quickly destroyed. Personally, I find it surprising that CO has such a critical role in the nervous system. Surprised or not, there it is and there is no doubt about it. 

Central Nervous System (CNS). The human nervous system is an integrated communication network that sends and receives information throughout the body. This network is divided into two main divisions central nervous system (CNS) and peripheral nervous system (PNS). The CNS is the command center of this network and is made up of the brain and spinal cord. The PNS is the interface of the nervous system with the rest of the body and the external environment. It is comprised of nerve fibers and small clusters of nerve cells known as ganglia. 

Further data on the effects of chronic inhalation exposure to 1,4-dichlorobenzene would be useful, especially because chronic exposures to 1,4-dichlorobenzene in the air, in the home, and the workplace are the main sources of human exposure to this chemical. Any further testing of the effects of chronic exposure to 1,4-dichlorobenzene via the oral route should probably be done at lower levels of 1,4-dichlorobenzene than those that have already been used in the NTP (1987) bioassay, and should focus on dose-response relationships involving the hepatic, renal, hematopoietic, central nervous system, and metabolic pathways. Data on the effects of chronic dermal exposure to 1,4-dichlorobenzene may be useful if dermal absorption and systemic distribution of 1,4-dichlorobenzene can be demonstrated from toxicokinetic studies, since chronic dermal exposure to 1,4-dichlorobenzene occurs as a result of bathing and showering in drinking water that contains low levels of this chemical in many U.S. communities. 

The peripheral nerves of the body communicate sensation and deliver commands from the central nervous system to move muscles from our fingers to our toes - quite... 

T. Murata, S. Sakaya, T. Hoshino, T. Umetsu, T. Hirano, S. Nishio, General pharmacology of beraprost sodium. 1st Communication Effect on the central nervous system, Arzneim. Forsch. 39(11) (1989) 860. 

How are the 10 neurons in the central nervous system arranged to process information How do they communicate through their 10 -10" connections with each other Most importantly for psychiatrists how can environmental influences, such as a pharmacological intervention or psychotherapy, influence the way in which the brain processes information ... 

We recently surveyed pharmaceutical companies producing antidepressant medication or central nervous system (CNS) stimulants for the European market. Approval for use of such drugs in children and adolescents is limited worldwide. Sertraline, clomipramine, and flu-voxamine have been approved for use in children (for some drugs down to the age of 6 years) for OCD in some European countries (the most wide spread approval being for sertraline in Austria, France, Hungary, Italy, Latvia, Norway, Portugal, Romania, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom, and Denmark) and countries outside Europe. Methyl-phenidate has been approved for the treatment of children with ADHD in a number of European and non-European countries (Novartis Health care A/S, personal communication). 

Neurons are the specialized cells through which virtually all the processes that occur in the central nervous system take place, from the control of movement and autonomic functions like breathing to complicated tasks like producing conscious thoughts. Internally, neurons use a combination of chemical and electrical signals, while communication between neurons is done mainly through chemical messengers called neurotransmitters. 

Peptides are used by most tissues for cell-to-cell communication. As noted in Chapters 6 and 21, they play important roles in the autonomic and central nervous systems. Several peptides exert important direct effects on vascular and other smooth muscles. These peptides include vasoconstrictors (angiotensin II, vasopressin, endothelins, neuropeptide Y, and urotensin) and vasodilators (bradykinin and related kinins, natriuretic peptides, vasoactive intestinal peptide, substance P, neurotensin, calcitonin gene-related peptide, and adrenomedullin). This chapter focuses on the smooth muscle actions of the peptides. 

Xylene was mentioned as an exposure in four studies. Two were community-based case-control studies, one of which involved brain cancer and one involved several types of cancer. The two industry-based studies were configured as nested case-control studies, one of central nervous system tumours and one of several sites. In none of these studies was xylene the sole or predominant exposure. Cancers at most sites were not significantly associated with xylene exposure in any study. Incidence of colorectal cancer was significantly elevated in the Canadian case-control study, but no other study reported colorectal cancer results. Hodgkin s disease was elevated in one study non-Hodgkin lymphoma was elevated in one study, but not in another. Most results were based on small numbers. In... 

There is much debate and considerable conflicting evidence regarding the mechanism of action of PCP. It is thought to stimulate alpha-adrenergic receptors in the brain and to elevate epinephrine, norepinephrine, and serotonin levels. PCP is also thought to inhibit communication along certain central nervous system pathways. Still others think that PCP acts on opiate receptors. 

Veelaert D., Schoofs L., Verhaert P. and De Loof A. (1997) Identification of two novel peptides from the central nervous system of the desert locust, Schistocerca gregaria. Biochem. Biophys. Res. Commun. 241, 530-534. 

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