Other receptors

Chemoreceptors are important bioanalytical tools because of their specific abilities in molecular recognition. Associated with a suitable receptor, a biosensor can detect proteins, toxins, hormones, chemical derivatives, or living cells, in both gaseous or liquid media. The weak dissociation constant of the complex formed (K 10 for the cobratoxin/acetylcholine-receptor complex, and K 10 ° for the insulin/insulin-receptor complex) means that such biosensors can be purified by affinity chromatography, and detect a specific ligand associated with the bioreceptor at extremely low concentrations. 

A recent sensor exploits a modification in the dielectric constants of the biochemical layer and the aqueous film resulting from the association of the receptor with its ligand. This interaction can be observed with a planar capacitive transducer [93] equipped with a silicon substrate covered with an Si02 layer 1 i.m thick. The protein Ca2+Mg2+ ATPase can be immobilized on this layer to detect the snake 

Future olfactive (olfactive mucus) detection systems will probably be ultrasensitive chemical sensors [16] detecting nucleotides and hormones (e.g., pheromones). Biosensor research may also become orientated towards new bioreceptors [265], and perhaps even new biocatalysts, such as artificial enzymes [266]. 

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Phenylephrine (90) is a selective receptor agonist (+)-niguldipine (91) is a selective antagonist for the receptor. Pra2osin (92) and 5-methylurapidil (93) are nonselective a -receptor antagonists. CEC can differentiate receptors from the other receptors. Pra2osin has low and high affinity for and receptors, respectively. 

Steroid Hormones and Neurosteroids. Steroids (qv) can affect neuroendocrine function, stress responses, and behavioral sexual dimorphism (78,79) (see Steroids). Mineralocorticoid, glucocorticoid, androgen, estrogen, and progesterone receptors are localized in the brain and spinal cord. In addition to genomic actions, the neurosteroid can act more acutely to modulate the actions of other receptors or ion channels (80). Pregnenolone [145-13-17, ( ) dehydroepiandosterone [53-43-0] C H2 02 (319) are excitatory neurosteroids found in rat brain, independent of adrenal... 

There are probably several processes that contribute to the total desensitization process and these may be directed homologously (to own receptor) or heterologously (to other receptor). Additionally, the induences may be directed at the receptor itself and affect only that receptor, ie, specific desensitization, or may affect other receptor processes as well, ie, nonspecific desensitization. 

Correlation between clinical effectiveness and receptor affinities, however, can be seen with other receptors in addition to the dopamine D2 receptor. These include other dopaminergic receptors, as well as noradrenergic and serotonergic receptors. For example, most antipsychotics also have high affinity for a -adrenoceptors and 5-HT2 receptors (225). Some antipsychotics have been shown to be selective for the adrenoceptor versus the a -adrenoceptor, for example, spiperone [749-02-0] (226) and risperidone (61) (221]... 

The harmful effects of air pollutants on human beings have been the major reason for efforts to understand and control their sources. During the past two decades, research on acidic deposition on water-based ecosystems has helped to reemphasize the importance of air pollutants in other receptors, such as soil-based ecosystems (1). When discussing the impact of air pollutants on ecosystems, the matter of scale becomes important. We will discuss three examples of elements which interact with air, water, and soil media on different geographic scales. These are the carbon cycle on a global scale, the sulfur cycle on a regional scale, and the fluoride cycle on a local scale. 

Ternary complex (model), this model describes the formation of a complex among a ligand (usually an agonist), a receptor, and a G-protein. Originally described by De Lean and colleagues (J. Biol. Chem. 255, 7108-7117, 1980), it has been modified to include other receptor behaviors (see Chapters 3.8 to 3.11), such as constitutive receptor activity. 

Recent studies indicate that - like many other receptors - G-protein-coupled receptors may form dimers, either homodimers or dimers with another type of receptor. The role of dimer formation in the cell surface expression of receptors and in their signalling and the resultant pharmacology are currently under intensive investigation [1]. 

The nicotinic acetylcholine (nACh) receptor also displays sensitivity to inhalants (Bale et al. 2002). To varying degrees, toluene appeared to antagonize the function of nACh receptors that comprise different subunits. At concentrations of 50 pM to 10 mM, toluene produced a reversible, concentration-dependent inhibition of acetylcholine-induced current in Xenopus oocytes expressing various nicotinic receptor subtypes, with the ol — 2 d ct3—P2 subunit combinations being more sensitive to inhibition than other receptor... 

The nuclear receptor superfamily consists of a diverse set of transcription factors that were discovered because of a sequence similarity in their DNA-binding domains. This family, now with more than 50 members, includes the nuclear hormone receptors discussed above, a number of other receptors whose ligands were discovered after the receptors were identified, and many putative or orphan receptors for which a ligand has yet to be discovered. 

Among the known chemokine receptors, CXCR4 has been established to play a crucial role in the nervous system physiology as evidenced by either CXCL12 or CXCR4 homozygous mutants phenotype (Ma et al. 1998 Zou et al. 1998). The other receptors discussed in this review are primarily involved in inflammatory and/ or neurodegenerative disorders which is consistent with their roles as inflammatory chemokines. 

Certainly clozapine can avoid EPSs by only blocking a fraction of D2 receptors but that seems insufficient on its own to make clozapine so effective in schizophrenia. That is probably achieved by a unique combination of other blocking actions, at Di, D4, 5-HT2, o 2 and possibly other receptors (see Fig. 17.8). It may simply be that clozapine is so effective because it is so dirty , a view held for many years about the first neuroleptic chlorpromazine. Indeed it is unlikely that the varied symptoms of such a complicated disorder could be rectified by manipulating just one NT. 

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