Neurotransmitter receptors dopaminergic receptor

Numerous neurotransmitter receptors are located in the vomiting center, CTZ, and GI tract. Examples of such receptors include cholinergic and histaminic, dopaminergic, opiate, serotonin, neurokinin (NK), and benzodiazepine receptors. Theoretically, chemotherapeutic agents, their metabolites, or other emetic compounds trigger the process of emesis through stimulation of one or more of these receptors. 

Several classes of drugs, notably the antipsychotics, discussed in Chapter 34, interfere with dopaminergic transmission. In general, dopamine appears to be an inhibitory neurotransmitter. Five dopamine receptors have been identified the most important and best studied are the Dj. and D2.receptor groups. The Dj receptor, which increases cyclic adenosine monophosphate (cAMP) by activation of adenylyl cyclase, is located primarily in the region of the putamen, nucleus accum-bens, and in the olfactory tubercle. The D2 receptor decreases cAMP, blocks certain calcium channels, and opens certain potassium channels. 

While dopamine is an intermediate for NE and E, it is also a neurotransmitter in its own right. Dopamine and the dopaminergic receptor, as well as drugs that act on it, are discussed below. 

The problem with the tricyclic-based neurotransmitter-receptor hypothesis of antidepressant activity is that it was based on observations in normal rat brain. Unfortunately, there are few techniques suitable for in vivo work on human CNS receptors of depressed patients. In addition, compounds related to dopaminergic and serotonergic... 

There are a host of receptors for each neurotransmitter with varying types of responses. For example, the four subtypes of adrenergic receptors which we saw in the PNS are also present in the CNS (ai, a2, Pl, P )-Cholinergic receptors come in two flavors, Mi and M2, while dopaminergic receptors show an elevation of cAMP levels upon stimulation of Di types and a decrease in cAMP after D2 stimulation. Opiate receptors (n,m, , k, ct) are the subject of intensive study as are 5-HT receptors. Drawn below are a few of the known CNS neurotransmitters and their activities as postulated. 

Dopamine has multiple actions on the cardiovascular system. Unfortunately dopamine is not a selective drug for dopamine receptors. Whereas we may strive to define actions of drugs or neurotransmitters as dopaminergic, these end points have been frequently defined under less than ideal conditions. 

Olanzapine Alcohol Olanzapine is a second generation antipsychotic used to treat schizophrenia and mania related to bipolar disorder. Olanzapine binds neurotransmitter receptors of several classes including dopaminergic, adrenergic, and serotonergic receptors [249, 250]. 

Citalopram has little affinity for neurotransmitter receptors like muscarinic, adrenergic, dopaminergic, serotonergic (b-HTj. g, S-HT ) histaminergic (Hj) benzodiazepine and opioid receptors [75 and references therein]. 

Stimulate and DA can inhibit cat carotid body neural output. Second, nicotinic, muscarinic, and dopaminergic receptors act in the cat carotid body as they do elsewhere. Thus, exocytotically released ACh and DA should stimulate and inhibit, respectively, postsynaptic neural traffic in the carotid sinus nerve. PresynapticaUy (i.e., on the glomus cells) the presence of the receptors would suggest that—as in other species— they can regulate by positive/negative feedback their own release from the glomus cells and, perhaps, the release of other neurotransmitters. 

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