GABA Receptor molecules of insects

Impulsivity is a complex trait that varies across healthy individuals, although when excessive, it is generally regarded as dysfunctional. Impulsive behavior may lead to initiation of drug addiction that interferes with inhibitory controls, which may in turn result in facilitation of the individual’s impulsive acts. Although environmental factors play a considerable role in impulsive behavior, a body of evidence collected in twin studies suggests that about 45% of the variance in impulsivity is accounted for by genetic factors. Genetic variants studied in association with impulsivity include those fortryptophan hydroxylase 1 and 2 (TPH1 and TPH2), the serotonintransporter (SERT), serotonin receptors, and genes of the monoamine metabolism pathway (e.g., monoamine oxidase A, MAOA). Other systems may also play a role in these behaviors, such as the dopaminergic system (the dopamine receptors DRD2, DRD3, and DRD4, and the dopamine transporter, DAT), the catecholaminergic system (catechol-O-methyltransferase, COMT), and the GABAergic system (GABAreceptor subunit alpha-1, GABRA1; GABA receptor subunit alpha-6, GABRA6; and GABA receptor subunit beta-1, GABRB1). Taking into account involvement of the hypothalamic-pituitary-adrenal (HPA) axis, the number of candidate genes implicated in impulsivity may be increased significantly and, therefore, may go far beyond those of serotonergic and dopaminergic systems. For a number of years, our group has conducted studies of the association of genes involved in the modulation of the stress-responsive HPA axis and several neurotransmitter systems, all involved in the pathophysiology of anxiety and depressive disorders, impulse control and compulsive disorders, with drug addiction. These genes include those of the opioid system: the mu- and kappa-opioid receptors (OPRM1 and OPRK1) and the nociceptin/orphaninFQ receptor (OPRL1); the serotonergic system: TPH1 and TPH2 and the serotonin receptor 1B (5THR1B); the catecholamine system: COMT; the HPA axis: themelanocortin receptor type 2 (MC2R or adrenocorticotropic hormone, ACTHR); and the cannabinoid system: the cannabinoid receptor type 1 (CNR1). In this chapter we will focus on these findings.

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Heterogeneous expression of GABA receptor‐like subunits LCCH3 and GRD reveals functional diversity of GABA receptors in the honeybee Apis mellifera

British Journal of Pharmacology ◽

10.1111/bph.15135 ◽

2020 ◽

Vol 177 (17) ◽

pp. 3924-3940

Author(s):

Christopher Henry ◽

Thierry Cens ◽

Pierre Charnet ◽

Catherine Cohen‐Solal ◽

Claude Collet ◽

...

Keyword(s):

Apis Mellifera ◽

Functional Diversity ◽

Gaba Receptors ◽

Gaba Receptor ◽

Heterogeneous Expression

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Subcellular Localization and Complements of GABAA and GABAC Receptors on Bullfrog Retinal Bipolar Cells

Journal of Neurophysiology ◽

10.1152/jn.2000.84.2.666 ◽

2000 ◽

Vol 84 (2) ◽

pp. 666-676 ◽

Cited By ~ 37

Author(s):

Jiu-Lin Du ◽

Xiong-Li Yang

Keyword(s):

Subcellular Localization ◽

Receptor Antagonist ◽

Gaba Receptor ◽

Drug Application ◽

Bipolar Cells ◽

Visual Signals ◽

Receptor Subtypes ◽

Inner Retina ◽

Axon Terminals ◽

Retinal Bipolar Cells

γ-Aminobutyric acid (GABA) receptors on retinal bipolar cells (BCs) are highly relevant to spatial and temporal integration of visual signals in the outer and inner retina. In the present work, subcellular localization and complements of GABAA and GABACreceptors on BCs were investigated by whole cell recordings and local drug application via multi-barreled puff pipettes in the bullfrog retinal slice preparation. Four types of the BCs (types 1–4) were identified morphologically by injection of Lucifer yellow. According to the ramification levels of the axon terminals and the responses of these cells to glutamate (or kainate) applied at their dendrites, types 1 and 2 of BCs were supposed to be off type, whereas types 3 and 4 of BCs might be on type. Bicuculline (BIC), a GABAA receptor antagonist, and imidazole-4-acetic acid (I4AA), a GABAC receptor antagonist, were used to distinguish GABA receptor-mediated responses. In all BCs tested, not only the axon terminals but also the dendrites showed high GABA sensitivity mediated by both GABAA and GABACreceptors. Subcellular localization and complements of GABAA and GABAC receptors at the dendrites and axon terminals were highly related to the dichotomy of offand on BCs. In the case of off BCs, GABAA receptors were rather evenly distributed at the dendrites and axon terminals, but GABAC receptors were predominantly expressed at the axon terminals. Moreover, the relative contribution of GABAC receptors to the axon terminals was prevalent over that of GABAA receptors, while the situation was reversed at the dendrites. In the case of on BCs, GABAA and GABAC receptors both preferred to be expressed at the axon terminals; relative contributions of these two GABA receptor subtypes to both the sites were comparable, while GABAC receptors were much less expressed than GABAA receptors. GABAA, but not GABAC receptors, were expressed clusteringly at axons of a population of BCs. In a minority of BCs, I4AA suppressed the GABAC responses at the dendrites, but not at the axon terminal, implying that the GABAC receptors at these two sites may be heterogeneous. Taken together, these results suggest that GABAA and GABAC receptors may play different roles in the outer and inner retina and the differential complements of the two receptors on off and on BCs may be closely related to physiological functions of these cells.

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