Intracellular effectors and modulators of GABA-A and GABA-B receptors: a commentary

(-)-baclofen and gamma-aminobutyric acid inhibit calcium currents in isolated retinal ganglion cells.

“…Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30). This may not be the only rationale for coexpressing GABAA and GABAB receptors because responses mediated by some GABAA receptors are enhanced by internal Ca2+ (31) and not all GABAB receptors are coupled to Ca2+ channels (9,10,13,29).…”

“…A possible advantage of colocalizing GABAA and GABAB receptors in single cells may be to decrease calcium permeability via activation ofthe GABAB receptor (10,29) and thus minimize Ca2' influx into cells depolarized by GABAA receptor-mediated Cl-efflux (4,9) or by other inputs. Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30).…”

(-)-baclofen and gamma-aminobutyric acid inhibit calcium currents in isolated retinal ganglion cells.

“…Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30). This may not be the only rationale for coexpressing GABAA and GABAB receptors because responses mediated by some GABAA receptors are enhanced by internal Ca2+ (31) and not all GABAB receptors are coupled to Ca2+ channels (9,10,13,29).…”

“…A possible advantage of colocalizing GABAA and GABAB receptors in single cells may be to decrease calcium permeability via activation ofthe GABAB receptor (10,29) and thus minimize Ca2' influx into cells depolarized by GABAA receptor-mediated Cl-efflux (4,9) or by other inputs. Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30).…”

Reductionist perspectives and the notion of information

“…This reductionism groups the idea that the elementary components can explain the complex with the idea that biology has to be reduced into the language and the laws of chemistry and physics (See Rosenberg, 1985). Francis Crick, for instance, thought that explaining the living by its elementary dynamics corresponds to the conviction that biology is subordinated to physics (See Feltz, 1995). In this context, the Central Dogma is not only reductionist but strongly deterministic.…”

γ‐Aminobutyric AcidB Receptor Activation Modifies Agonist Binding to β‐Adrenergic Receptors in Rat Brain Cerebral Cortex

“…There are at least two receptor subtypes for y-aminobutyric acid (GABA): GABAA and GABAB. The GABAA receptors are associated with C1-flux (Enna and Gallagher, 1983), whereas GABAB receptor activation alters K+ and Ca2+ channels (Gahwiler and Brown, 1985;Feltz et al, 1987) and modifies second messenger production. With regard to second messengers, baclofen, a selective GABAB receptor agonist (Hill and Bowery, 198 1 ), augments neurotransmitter-stimulated cyclic AMP accumulation in brain slices while having no direct effect on second messenger formation (Hill, 1985;Karbon and Enna, 1985;Watling and Bristow, 1986).…”

(-)-baclofen and gamma-aminobutyric acid inhibit calcium currents in isolated retinal ganglion cells.

“…Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30). This may not be the only rationale for coexpressing GABAA and GABAB receptors because responses mediated by some GABAA receptors are enhanced by internal Ca2+ (31) and not all GABAB receptors are coupled to Ca2+ channels (9,10,13,29).…”

“…A possible advantage of colocalizing GABAA and GABAB receptors in single cells may be to decrease calcium permeability via activation ofthe GABAB receptor (10,29) and thus minimize Ca2' influx into cells depolarized by GABAA receptor-mediated Cl-efflux (4,9) or by other inputs. Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30).…”

Reductionist perspectives and the notion of information

“…This reductionism groups the idea that the elementary components can explain the complex with the idea that biology has to be reduced into the language and the laws of chemistry and physics (See Rosenberg, 1985). Francis Crick, for instance, thought that explaining the living by its elementary dynamics corresponds to the conviction that biology is subordinated to physics (See Feltz, 1995). In this context, the Central Dogma is not only reductionist but strongly deterministic.…”

γ‐Aminobutyric AcidB Receptor Activation Modifies Agonist Binding to β‐Adrenergic Receptors in Rat Brain Cerebral Cortex

“…There are at least two receptor subtypes for y-aminobutyric acid (GABA): GABAA and GABAB. The GABAA receptors are associated with C1-flux (Enna and Gallagher, 1983), whereas GABAB receptor activation alters K+ and Ca2+ channels (Gahwiler and Brown, 1985;Feltz et al, 1987) and modifies second messenger production. With regard to second messengers, baclofen, a selective GABAB receptor agonist (Hill and Bowery, 198 1 ), augments neurotransmitter-stimulated cyclic AMP accumulation in brain slices while having no direct effect on second messenger formation (Hill, 1985;Karbon and Enna, 1985;Watling and Bristow, 1986).…”

(-)-baclofen and gamma-aminobutyric acid inhibit calcium currents in isolated retinal ganglion cells.

“…Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30). This may not be the only rationale for coexpressing GABAA and GABAB receptors because responses mediated by some GABAA receptors are enhanced by internal Ca2+ (31) and not all GABAB receptors are coupled to Ca2+ channels (9,10,13,29).…”

“…A possible advantage of colocalizing GABAA and GABAB receptors in single cells may be to decrease calcium permeability via activation ofthe GABAB receptor (10,29) and thus minimize Ca2' influx into cells depolarized by GABAA receptor-mediated Cl-efflux (4,9) or by other inputs. Without the GABAB receptor, a voltage-activated Ca2+ influx could produce increases in intracellular Ca2" levels large enough (25) to reduce the chloride currents activated via certain GABAA receptors (29,30).…”

Reductionist perspectives and the notion of information

“…This reductionism groups the idea that the elementary components can explain the complex with the idea that biology has to be reduced into the language and the laws of chemistry and physics (See Rosenberg, 1985). Francis Crick, for instance, thought that explaining the living by its elementary dynamics corresponds to the conviction that biology is subordinated to physics (See Feltz, 1995). In this context, the Central Dogma is not only reductionist but strongly deterministic.…”

γ‐Aminobutyric AcidB Receptor Activation Modifies Agonist Binding to β‐Adrenergic Receptors in Rat Brain Cerebral Cortex

“…There are at least two receptor subtypes for y-aminobutyric acid (GABA): GABAA and GABAB. The GABAA receptors are associated with C1-flux (Enna and Gallagher, 1983), whereas GABAB receptor activation alters K+ and Ca2+ channels (Gahwiler and Brown, 1985;Feltz et al, 1987) and modifies second messenger production. With regard to second messengers, baclofen, a selective GABAB receptor agonist (Hill and Bowery, 198 1 ), augments neurotransmitter-stimulated cyclic AMP accumulation in brain slices while having no direct effect on second messenger formation (Hill, 1985;Karbon and Enna, 1985;Watling and Bristow, 1986).…”