Posted by Shawn. T. on July 29, 2002, at 20:57:56
I hope that these definitions are not too difficult to grasp; I have also tried to add additional definitions for confusing words included in definitions. I have modified many of the definitions by cutting out extraneous information.
Neuropeptide: Any of various short-chain peptides found in brain tissue, such as endorphins.
Tissue: An aggregation of morphologically similar cells and associated intercellular matter acting together to perform one or more specific functions in the body. There are four basic types of tissue: muscle, nerve, epidermal, and connective.
Endorphin: Any of a group of peptide hormones that bind to opiate receptors and are found mainly in the brain. Endorphins reduce the sensation of pain and affect emotions.
Peptide: Any of various natural or synthetic compounds containing two or more amino acids linked by the carboxyl group of one amino acid to the amino group of another. The following link has excellent information on peptides.
http://web.indstate.edu/thcme/mwking/peptide-hormones.htmlAmino acid: building block of proteins
Protein: Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur and are composed of one or more chains of amino acids. Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism
Hormone: A substance, usually a peptide or steroid, produced by one tissue and conveyed by the bloodstream to another to effect physiological activity, such as growth or metabolism.
Steroid: Any of numerous naturally occurring or synthetic fat-soluble organic compounds having as a basis 17 carbon atoms arranged in four rings and including the sterols and bile acids, adrenal and sex hormones, certain natural drugs such as digitalis compounds, and the precursors of certain vitamins.
Organic: Of or designating carbon compounds.
Metabolism: The chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. In metabolism some substances are broken down to yield energy for vital processes while other substances, necessary for life, are synthesized.
Metabolite: Many drugs are converted or metabolized by chemical activity into other chemicals. This metabolism of a drug may result in production of one or more metabolites of the original drug.
Neuron: Any of the impulse-conducting cells that constitute the brain, spinal column, and nerves, consisting of a nucleated cell body with one or more dendrites and a single axon. The same thing as a nerve cell.
Axon: The usually long process of a nerve fiber that generally conducts impulses away from the body of the nerve cell.
Dendrite: A branched protoplasmic extension of a nerve cell that conducts impulses from adjacent cells inward toward the cell body. A single nerve may possess many dendrites.
Protoplasm: The entire contents of a live cell. (Doesn't the previous definition seem somewhat redundant?)
5-HT: 5-hydroxytryptamine. The same thing as serotonin.
Serotonin: An organic compound formed from tryptophan and found in animal and human tissue, especially the brain, blood serum, and gastric mucous membranes, and active as a neurotransmitter and in vasoconstriction, stimulation of the smooth muscles, and regulation of cyclic body processes.
Noradrenaline: A substance, which can be both a hormone and neurotransmitter, secreted by the adrenal medulla and the nerve endings of the sympathetic nervous system to cause vasoconstriction and increases in heart rate, blood pressure, and the sugar level of the blood. Also called norepinephrine.
Dopamine: A monoamine neurotransmitter formed in the brain by the decarboxylation of dopa and essential to the normal functioning of the central nervous system.
Monoamine: An amine compound containing one amino group, especially a compound that functions as a neurotransmitter.
Receptor: A molecular structure or site on the surface or interior of a cell that binds with substances such as hormones, antigens, drugs, or neurotransmitters.
Antigen: : any substance (as a toxin or enzyme) that stimulates the production of antibodies.
Enzyme: any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions.
Catalyst: A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.
Reaction: A change or transformation in which a substance decomposes, combines with other substances, or interchanges constituents with other substances.
G Protein: Any of a family of similar proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and Gi inhibits enzyme activity.
Plasma: The clear, yellowish fluid portion of blood, lymph, or intramuscular fluid in which cells are suspended.
Membrane: A thin, pliable layer of tissue covering surfaces or separating or connecting regions, structures, or organs of an animal or a plant.
Neurotransmission: the process by which information is transferred from one neuron to another across the synapse. Involves the release of a neurotransmitter from the pre-synaptic nerve ending in response to the arrival of an action potential and influx of Ca++ (calcium ion) and the subsequent activation of a receptor on the membrane of the post-synaptic neuron. Activation of the post-synaptic receptor may result in either excitation or inhibition.
Excitatory synapse: one in which the firing of the presynaptic cell increases the probability of firing of the postsynaptic cell.
Inhibitory synapse: one in which the firing of the presynaptic cell reduces the probability of firing of the postsynaptic cell.GABA: an amino acid that is found in the central nervous system; acts as an inhibitory neurotransmitter. Also known as gamma aminobutyric acid.
GABAa, GABAb: subtypes of GABA receptors. The GABAa receptor is part of a complex with multiple binding sites (benzodiazepine, steroid, barbiturate etc). Benzodiazepines are agonists at a site occupation of which facilitates the ability of GABA to bind to its site. Barbiturates bind directly to the Cl- ionophore. Bicuculline is an antagonist of the GABAa binding site while muscimol is an agonist at that site.
Inhibition: membrane hyperpolarisation either due to direct effect on an ion channel or enzyme inhibition via a G protein coupled second messenger system.
Glutamate: Glutamate - is an example of a fast acting excitatory transmitter where the receptors (NMDA, AMPA) are directly linked to a Na+ [sodium ion] channel. GABA is the major fast acting inhibitory transmitter. Activation of the GABAa receptor, which is linked to a Cl- [chloride ion] channel, results in an influx of Cl- into the neurone causing hyperpolarisation.
Excitation: membrane depolarisation caused either by a direct effect on an ion channel (fast neurotransmission) or through a G protein coupled second messenger system (slow neurotransmission).
Second messenger: In many hormone sensitive systems the systemic hormone does not enter the target cell but binds to a receptor and indirectly affects the production of another molecule within the cell, this diffuses intracellularly to the target enzymes or intracellular receptor to produce the response. This intracellular mediator is called the second messenger.
cAMP: Generated from ATP by the action of adenylyl cyclase that is coupled to hormone receptors by G-proteins (GTP-binding proteins). CAMP activates a specific (cAMP dependent) protein kinase.
ATP: A nucleotide present in all living cells which serves as an energy source for many metabolic processes and is required for ribonucleic acid [rna] synthesis.
Nucleotide: a type of molecule.
Adenylyl cyclase: a type of enzyme that acts as an intracellular second messenger of neural or hormonal activation. Also called adenylate cyclase (or even adenyl cyclase, no one can make up their mind).
Ion: Atomic particle, atom or chemical radical bearing an electric charge, either negative or positive.
Hyperpolarisation: A negative shift in a cells resting potential (which is normally negative), thus making it numerically larger i.e. More polarized. The opposite of depolarisation.
Depolarisation: The reversal of the resting potential in excitable cell membranes when stimulated i.e., the tendency of the cell membrane potential to become positive with respect to the potential outside the cell. A positive shift in a cells resting potential (that is normally negative), thus making it numerically smaller and less polarized, for example 90mV to 50mV.
Resting potential: The electrical potential of the inside of a cell, relative to its surroundings. Almost all animal cells are negative inside, resting potentials are in the range 20 to 100mV, 70mV typical.
Action potential: The sequential, electrochemical polarization and depolarisation that travels across the membrane of a nerve cell (neuron) in response to stimulation (touch, pain, cold, etc.)
Autoreceptor: Transmitter receptors on or near presynaptic terminals (or varicosities) which are sensitive to the transmitter(s) released by the terminal itself. Receptors for the hormones released by hormone-releasing cells are also included.
Heteroceptor: A receptor that modulates the release of neurotransmitters other than those that stimulate it.
Bind: Drugs as well as intrinsic molecules such as hormones and neurotransmitters may be said to bind to receptors, but may also be bound by other molecules or strucutures without producing a specific effect.
Downregulation: A reduction in the usual intensity of response associated with exposure of a receptor to the same concentration of agonist neurotransmitter can result from a decrease in the density or the absolute number of a particular receptor.
Upregulation: An increase in the usual intensity of response associated with exposure of a receptor to the same concentration of agonist neurotransmitter can result from an increase in the density or the absolute number of a particular receptor.
Amine neurotransmitters: Include dopamine (DA) noradrenaline (NA), serotonin (5HT) and acetylcholine (ACh). Generally act as slow excitatory or inhibitory transmitters depending upon their receptor coupling system. This explains their wide role in the long-term modulation of behaviour. Some amine receptors are directly coupled to ion channels (5HT3, cholinergic nicotinic receptors).
HPA axis: Hypothalamic-pituitary-adrenal axis.
Phospholipase C/inositol tris-phosphate/diacylglycerol: Activation of this system results in the formation of two intracellular messengers (IP3 and DAG). IP3 increases free Ca++ thus activating various enzymes. DAG activates protein kinase C which in turn regulates various cellular functions
Protein kinase C: An enzyme that phosphorylates proteins on serine or threonine residues in the presence of physiological concentrations of calcium and membrane phospholipids. The additional presence of diacylglycerols markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by phorbol esters and it is believed that protein kinase c is the receptor protein of tumour-promoting phorbol esters.
Phosphorylation: The creation of a phosphate derivative of an organic molecule. This isusually achieved by transferring a phosphate group from ATP.
Calcium: An element taken in through the diet that is essential for a variety of bodily functions, such as neurotransmission, muscle contraction and proper heart function. Imbalances of calcium can lead to many health problems and excess calcium in nerve cells can cause their death.
5-HT receptors: There are 14 Serotonin receptors, all are G-protein coupled apart from 5HT3 (ligand-gated cation channel). The 5HT1 group, (5HT1A, 5HT1B, 5HT1D) are inhibitory and are negatively coupled to adenylate cyclase. The 5HT1A is found both at pre-synaptic (somatodendritic autoreceptor) and post-synaptic sites including the hippocampus and PAG where importantly it regulates behaviours such as resilience, impulsivity and restraint of excessive response to stress. The 5-HT1A receptor may be an important target in the action of antidepressants. 5HT2 receptors (5HT2A , 5HT2B, 5HT2C) are excitatory and act through the phospholipase C/inositol phosphate pathway. 5HT2A receptors are found in the cortex and are associated with sensory perception while 5HT2C receptors when activated reduce food intake and induce anxiety/panic.
The 5HT4, 5HT5, 5HT6 and 5HT7 receptors are positively coupled to adenylate cyclase and are thus excitatory. With regard to psychopharmacology the 5HT6 receptor antagonists have been shown, in animal studies, to increase aspects of memory, in particular retention of information and attention, while the 5HT7 receptor may have importance in depression and circadian functions (SCN).
HAM-A: Hamilton Anxiety Scale
http://www.fpnotebook.com/PSY71.htmHAM-D: Hamilton Depression Scale
http://www.fpnotebook.com/PSY83.htm-Most of these definitions are taken from http://www.dictionary.com
or
http://cancerweb.ncl.ac.uk/omd/index.html
or
http://www.behavenet.com/capsules/pharm/pharmacology.htm
or
http://www.ndif.org/Terms/G_protein.htmlThe others are from some of my notes; I'll post the source if I can find it. There are different definitions for each of these terms; I tried to choose ones that fit with my understanding. See
http://web.indstate.edu/thcme/mwking/home.html
for a very nice discussion of biochemistry. There is some information on cancer there that is very interesting. I'm slowly trying to work my way through this site.Shawn
poster:Shawn. T.
thread:114241
URL: http://www.dr-bob.org/babble/20020725/msgs/114241.html