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Dopamine is also synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. Neurotransmitters are synthesized in specific regions of the brain but affect many regions systemically.
Tachykinins are known to be highly excitatory neurotransmitters in major central neural systems. [3] Neurokinin A is ubiquitous in both the central and peripheral mammalian nervous systems, and seems to be involved in reactions to pain and the inflammatory responses. It is produced from the same preprotachykinin A gene as the neuropeptide ...
Excitotoxicity can occur from substances produced within the body (endogenous excitotoxins).Glutamate is a prime example of an excitotoxin in the brain, and it is also the major excitatory neurotransmitter in the central nervous system of mammals. [14]
The specific interaction between drugs and their receptors is referred to as "drug action", and the widespread changes in physiological or psychological function is referred to as "drug effect". [2] These drugs may originate from natural sources such as plants and animals, or from artificial sources such as chemical synthesis in the laboratory.
Convulsions are induced in captive animals, then high doses of anticonvulsant drugs are administered. [ 10 ] [ 11 ] [ 12 ] For example, kainic acid can lead to status epilepticus in animals as it is a cyclic analog of l-glutamate and an agonist for kainate receptors in the brain which makes it a potent neurotoxin and excitant.
The drugs they studied included cocaine and a few others that have some similarities to cocaine in how they affect the brain. They trained the monkeys to give themselves these drugs through injections and observed their behavior. They wanted to see if the drugs had similar effects on the monkeys.
The resulting change in voltage is called a postsynaptic potential. In general, the result is excitatory in the case of depolarizing currents, and inhibitory in the case of hyperpolarizing currents. Whether a synapse is excitatory or inhibitory depends on what type(s) of ion channel conduct the postsynaptic current(s), which in turn is a ...
The highest number of actions that the animal or human is willing to do to get the drug is called the break point. The higher the break point, the more the animal or human wants the drug. In contrast to the classical stimulants such as amphetamine, the effects of modafinil depend on what the animals or humans have to do after getting the drug.