Dopamine receptors influences

Other protein kinases may indirectly influence the activation of NF-kappap. For example, in contrast to the pro-inflammatory effects typically observed with activation of kinases, the elevation ofcAMP activates PKA and blocks transcription of iNOS mRNA [51,178, 229, 230]. Astrocytes contain a variety of NT receptors that are coupled to Gs-adenylate cyclase [231] and, either activation of P-adrenergic/dopamine receptors or employing agents that increase cAMP, such as forskolin (adenylate cyclase activator), PDE inhibitors [i.e. pentoxifylline], dibutyrl cAMP, or 8-bromo cAMP can attenuate lipopolysaccharide (LPS)/cytokine activated iNOS mRNA in microglia, astrocytes and a number of other cell types [51,176,177,178, 232-237]. In contrast, agents that suppress the intracellular concentration of cAM P such as H-89 and Rp-cAM P are pro-... 

Another potential clinical application of potent, peripherally acting DA agonists is the lowering of intraocular pressure in, for example, glaucoma [18]. There is in vivo and in vitro evidence that dopamine receptors might modulate the intraocular pressure. The influence of both agonists and antagonists for D1 and D2 receptors has been studied. Some human data are also available [19]. 

Harrod SB, Mactutus CF, et al (2004) Sex differences and repeated intravenous nicotine behavioral sensitization and dopamine receptors, Pharmacol Biochem Behav 78(3) 581-592 Hatchell PC, Collins AC (1980) The influence of genotype and sex on behavioral sensitivity to nicotine in mice. Psychopharmacology 71(1) 45 9 Henschke Cl, Miettinen OS (2004) Women s susceptibility to tobacco carcinogens. Lung Cancer 43(l) l-5... 

Sexual receptivity. The effects of THC on sexual behavior in female rats and its influence on steroid hormone receptors and neurotransmitters in the facilitation of sexual receptivity was examined. Results revealed that the facilitatory effect of THC was inhibited by antagonists to both progesterone and dopamine D(l) receptors. To test further the idea that progesterone receptors (PR) and/or dopamine receptors (D[1]R) in the hypothalamus were required for THC-facilitated sexual behavior in rodents, antisense, and sense oligonucleotides to PR and D(1)R were administered intra-cerebroventricularly into the third cerebral ventricle of ovariectomized, estradiol benzoate-primed rats. Progesterone- and THC-facilitated sexual behavior was inhibited in animals treated with antisense oligonucleotides to PR or to D(1)R. Antagonists to... 

Schizophrenia appears to be caused by an overactivity of dopamine pathways in certain parts of the brain such as the limbic system.2,23 This idea is based primarily on the fact that most antipsychotics block dopamine receptors, thereby reducing dopaminergic hyperactivity in mesolimbic pathways and other limbic structures (see the next section of this chapter). The increased dopamine influence underlying psychosis could be caused by excessive dopamine synthesis and release by the presynaptic neuron, decreased dopamine breakdown at the synapse, increased postsy-naptic dopamine receptor sensitivity, or a combination of these and other factors. 

Consequently, antipsychotic drugs all share a basic mechanism of action that involves dopamine receptor blockade. It is apparent, however, that they are not all equal in their ability to affect specific sub-types of dopamine receptors, and that their effectiveness and side effects are related to their affinity and preference for certain receptors. As indicated earlier, other neurotransmitters may also be involved in the pathogenesis of psychosis, and differences in specific antipsychotic medications may be related to their ability to directly or indirectly affect these other transmitters as well as block dopamine influence. Future studies will continue to clarify how current antipsychotics exert their beneficial effects and how new agents can be developed to be more selective in their effects on dopamine and other neurotransmitter pathways. 

Parkinsonian effects The inhibitory effects of dopaminergic neurons are normally balanced by the excitatory actions of cholinergic neurons. Blocking dopamine receptors alters this balance, causing a relative excess of cholinergic influence and resulting in extrapyramidal motor effects. 

Kimmel HL, Joyce AR, Carroll FI, Kuhar MJ (2001) Dopamine D1 and D2 receptors influence dopamine transporter synthesis and degradation in the rat. J Pharmacol Exp Ther 295 129-140. 

The substantial production and metabolism of dopamine in the human GI tract appear to reflect functions of dopamine as an enteric neuromodulator or paracrine and/or autocrine substance. Dopamine and dopamine receptor agonists stimulate bicarbonate secretion and protect against ulcer formation, whereas dopamine antagonists augment secretion of gastric acid and promote ulcer development. Dopamine also appears to influence GI motility, sodium transport, and gastric and intestinal submucosal blood flow. In the pancreas, dopamine may modulate secretion of digestive enzymes and bicarbonate. 

Doty RL, Risser JM. 1989. Influence of the D-2 dopamine receptor agonist quinpirole on the odor detection performance of rats before and after spiperone administration. Psychopharmacol 98 310-315. 

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