Dopamine D2 Receptor Dimer Formation - Essay Example

The experiment was successful in the sense that the inhibition constant for [3H]-spiperone at around 0.5 nM corresponded with that quoted in literature available on the subject. The experiment demonstrated that [3H]-spiperone is a very efficacious antagonist of dopaminergic activity in specific relation to receptor subtypes with very specific inhibition capabilities and very low inhibition constant. This may later prove valuable to drug development against disorders like schizophrenia that is caused by excessive dopaminergic activity.

The variations in physiologic actions of dopamine are mediated by at least five distinct G protein coupled receptor types (Missale, C., et al, 1998). Kebabian and Calne (1979) distinguished two dopamine receptor types - and - that can be differentiated ‘pharmacologically, biologically, physiologically and by their anatomical distribution’ (Civelli, O., 2000). Since the analysis is on receptors only they are being discussed here. Subsequent cloning of receptors revealed that they belonged to the supergene family of the G-protein coupled receptors (Civelli, O., 2000). The three subtypes belonging to the -like sub-family are the, and ones that inhibit adenylyl cyclase and activate channels (Missale, C.

, et al, 1998). The genetic structure of the and vary by tissue types and species’ through alternative splicing. The subtype is highly polymorphic. Since the analysis is on receptor activity on recombinant CHO (Chinese hamster ovary) cells it is necessary to point out that-like receptor activity in the peripheral regions is evident mostly in the kidney, vasculature and pituitary where they affect sodium homeostasis, vascular tone and hormone secretion (Missale, C., et al, 1998). More specifically the analysis of the gene structure of the subtype reveals that there are six introns in the receptor-coding region.

This generates two main variants – the (short) and (long) receptors – in turn