engleski

Recombinant receptors-model for neuropharmacological studies

A variety of expression systems for recombinant receptors have been developed such as: Xenopus oocytes, insect cells, mouse fibroblasts, Chinese hamster ovary cells, and human embryonic kidney 293 cells in order to investigate the structure, assembly, function, allosteric modulation, regulation and pharmacological properties of specific GABA-A receptor subtypes. Advantages of such models are: 1)Relatively homogenous clonal population of cells with minimal manipulation of the cellular environment and with genetic homogeneity 2) The cells can be cultured under tightly controlled conditions, where expression can be carefully monitored 3)Quick and easy reproduction and maintenance and relatively large amounts of expressed receptors obtained 4)Such homogenous cell population can be well- characterized and defined with respect to receptor subunit composition, structure and function. On the other hand the disadvantages of such models are 1)They represent artificial conditions: the expression of transfected genes may not be regulated in the same way as it is in vivo or in primary neuronal culture in which endogenous genes are involved 2) The expression mechanisms might be different due to a lack of normal neuronal environment, such as neurotransmitters, synapse and proteins involved in the targeting and stabilization of specific receptor subtypes at postsynaptic sites 3)Some factors which can affect the results include parent cell line, receptor species or subtype, promoter system and level of receptor expression. So far the literature data reveal the existence of at least:19 subunits of GABA-A receptors, 5 types of muscarinic receptors, 8 subtypes of metabotropic glutamate receptors, 14 mammalian 5-HT receptors, 5 dopamine receptor subtypes, 5 subtypes of adrenergic receptors etc. HEK 293 cells have been used to express a wide variety of recombinant proteins: voltage-sensitive ion channels, G- protein coupled receptors, ligand-gated ion channels, post-synaptic density proteins, including also adrenergic, dopamine receptors and serotonin receptors. Although these systems are a useful tool, the interpretations of the data obtained in vitro must be careful and such results should be confirmed by studies performed on native receptors or intact animals.

recombinant receptors; cell culture; long-term drug treatment; adaptive changes

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