Editing GABA receptor (section)

===GABA<sub>A</sub>-ρ receptor===
{{Main|GABAA-rho receptor}}

A subclass of [[ionotropic]] GABA receptors, insensitive to typical [[Allosteric regulation|allosteric modulators]] of GABA<sub>A</sub> receptor channels such as [[benzodiazepine]]s and [[barbiturate]]s,<ref name="pmid1847747">{{cite journal |vauthors=Sivilotti L, Nistri A | title = GABA receptor mechanisms in the central nervous system | journal = Prog. Neurobiol. | volume = 36 | issue = 1 | pages = 35–92 | year = 1991 | pmid = 1847747 | doi = 10.1016/0301-0082(91)90036-Z   | s2cid = 31732465 }}</ref><ref name="pmid8638289">{{cite journal |vauthors=Bormann J, Feigenspan A | title = GABAC receptors | journal = Trends Neurosci. | volume = 18 | issue = 12 | pages = 515–9 |date=December 1995 | pmid = 8638289 | doi = 10.1016/0166-2236(95)98370-E   | s2cid = 40853254 }}</ref><ref name="pmid8885697">{{cite journal | author = Johnston GA | title = GABAc receptors: relatively simple transmitter -gated ion channels? | journal = Trends Pharmacol. Sci. | volume = 17 | issue = 9 | pages = 319–23 |date=September 1996 | pmid = 8885697 | doi = 10.1016/0165-6147(96)10038-9 | doi-access = free }}</ref> was designated GABA<sub>С</sub> receptor.<ref name="pmid6097844">{{cite journal | vauthors=Drew CA, Johnston GA, Weatherby RP | title = Bicuculline-insensitive GABA receptors: studies on the binding of (-)-baclofen to rat cerebellar membranes | journal = Neurosci. Lett. | volume = 52 | issue = 3 | pages = 317–21 |date=December 1984 | pmid = 6097844 | doi = 10.1016/0304-3940(84)90181-2 | s2cid = 966075 }}</ref><ref name="pmid11239575">{{cite journal |vauthors=Zhang D, Pan ZH, Awobuluyi M, Lipton SA | title = Structure and function of GABA(C) receptors: a comparison of native versus recombinant receptors | journal = Trends Pharmacol. Sci. | volume = 22 | issue = 3 | pages = 121–32 |date=March 2001 | pmid = 11239575 | doi = 10.1016/S0165-6147(00)01625-4  }}</ref> Native responses of the GABA<sub>C</sub> receptor type occur in [[retina]]l bipolar or horizontal cells across vertebrate species.<ref name="pmid7678450">{{cite journal |vauthors=Feigenspan A, Wässle H, Bormann J | title = Pharmacology of GABA receptor Cl- channels in rat retinal bipolar cells | journal = Nature | volume = 361 | issue = 6408 | pages = 159–62 |date=January 1993 | pmid = 7678450 | doi = 10.1038/361159a0  | bibcode = 1993Natur.361..159F | s2cid = 4347233 }}</ref><ref name="pmid8421521">{{cite journal |vauthors=Qian H, Dowling JE | title = Novel GABA responses from rod-driven retinal horizontal cells | journal = Nature | volume = 361 | issue = 6408 | pages = 162–4 |date=January 1993 | pmid = 8421521 | doi = 10.1038/361162a0  | bibcode = 1993Natur.361..162Q | s2cid = 4320616 }}</ref><ref name="pmid8884747">{{cite journal | author = Lukasiewicz PD | title = GABAC receptors in the vertebrate retina | journal = Mol. Neurobiol. | volume = 12 | issue = 3 | pages = 181–94 |date=June 1996 | pmid = 8884747 | doi = 10.1007/BF02755587  | s2cid = 37167159 }}</ref><ref name="pmid9753143">{{cite journal |vauthors=Wegelius K, Pasternack M, Hiltunen JO, Rivera C, Kaila K, Saarma M, Reeben M | title = Distribution of GABA receptor rho subunit transcripts in the rat brain | journal = Eur. J. Neurosci. | volume = 10 | issue = 1 | pages = 350–7 |date=January 1998 | pmid = 9753143 | doi = 10.1046/j.1460-9568.1998.00023.x  | s2cid = 25863134 }}</ref>

GABA<sub>С</sub> receptors are exclusively composed of ρ (rho) subunits that are related to GABA<sub>A</sub> receptor subunits.<ref name="pmid1314944">{{cite journal |vauthors=Shimada S, Cutting G, Uhl GR | title = gamma-Aminobutyric acid A or C receptor? gamma-Aminobutyric acid rho 1 receptor RNA induces bicuculline-, barbiturate-, and benzodiazepine-insensitive gamma-aminobutyric acid responses in Xenopus oocytes | journal = Mol. Pharmacol. | volume = 41 | issue = 4 | pages = 683–7 |date=April 1992 | pmid = 1314944 | url = http://molpharm.aspetjournals.org/cgi/reprint/41/4/683 }}</ref><ref name="pmid8388298">{{cite journal |vauthors=Kusama T, Spivak CE, Whiting P, Dawson VL, Schaeffer JC, Uhl GR | title = Pharmacology of GABA rho 1 and GABA alpha/beta receptors expressed in Xenopus oocytes and COS cells | journal = Br. J. Pharmacol. | volume = 109 | issue = 1 | pages = 200–6 |date=May 1993 | pmid = 8388298 | pmc = 2175610 | doi = 10.1111/j.1476-5381.1993.tb13554.x }}</ref><ref name="pmid8386671">{{cite journal |vauthors=Kusama T, Wang TL, Guggino WB, Cutting GR, Uhl GR | title = GABA rho 2 receptor pharmacological profile: GABA recognition site similarities to rho 1 | journal = Eur. J. Pharmacol. | volume = 245 | issue = 1 | pages = 83–4 |date=March 1993 | pmid = 8386671 | doi = 10.1016/0922-4106(93)90174-8 }}</ref> Although the term "GABA<sub>С</sub> receptor" is frequently used, GABA<sub>С</sub> may be viewed as a variant within the GABA<sub>A</sub> receptor family.<ref name=Barnard/> Others have argued that the differences between GABA<sub>С</sub> and GABA<sub>A</sub> receptors are large enough to justify maintaining the distinction between these two subclasses of GABA receptors.<ref name="pmid10780899">{{cite journal |vauthors=Chebib M, Johnston GA | title = GABA-Activated ligand gated ion channels: medicinal chemistry and molecular biology | journal = J. Med. Chem. | volume = 43 | issue = 8 | pages = 1427–47 |date=April 2000 | pmid = 10780899 | doi = 10.1021/jm9904349 }}</ref><ref name="pmid10637650">{{cite journal | author = Bormann J | title = The 'ABC' of GABA receptors | journal = Trends Pharmacol. Sci. | volume = 21 | issue = 1 | pages = 16–9 |date=January 2000 | pmid = 10637650 | doi = 10.1016/S0165-6147(99)01413-3 }}</ref> However, since GABA<sub>С</sub> receptors are closely related in sequence, structure, and function to GABA<sub>A</sub> receptors and since other GABA<sub>A</sub> receptors besides those containing ρ subunits appear to exhibit GABA<sub>С</sub> pharmacology, the Nomenclature Committee of the [[International Union of Basic and Clinical Pharmacology|IUPHAR]] has recommended that the GABA<sub>С</sub> term no longer be used and these ρ receptors should be designated as the ρ subfamily of the GABA<sub>A</sub> receptors (GABA<sub>A</sub>-ρ).<ref name="pmid18790874">{{cite journal |vauthors=Olsen RW, Sieghart W | title = International Union of Pharmacology. LXX. Subtypes of γ-Aminobutyric AcidA Receptors: Classification on the Basis of Subunit Composition, Pharmacology, and Function. Update | journal = Pharmacological Reviews | volume = 60 | issue = 3 | pages = 243–60 |date=September 2008 | pmid = 18790874 | doi = 10.1124/pr.108.00505 | pmc = 2847512 }}</ref>