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BRS1 — Neurotransmitter Regulation

BRS1(FM4) - GABA–Glutamate Regulation​

(Neural Excitation–Inhibition Balance & Stability)

Primary Mechanisms​

1. Mission & Overview​

Objective​

Support coordinated excitatory and inhibitory signalling through GABA synthesis, glutamate clearance and recycling, and protection against excessive glutamate-receptor stimulation. [4] [7] [8].

Overview​

GABA synthesis supplies inhibitory transmitter, while glutamate uptake and recycling help terminate and replenish signalling [4] [7]. Protection against excessive glutamate-receptor stimulation is a separate, context-dependent safeguard [8]. These contributions support excitation–inhibition regulation, but receptor responses and synaptic adaptation remain outside the retained PM coverage; this FM does not claim comprehensive coverage [3].

  • Integrated capacity: transmitter formation, clearance/recycling and overload protection make distinct contributions rather than interchangeable measures of balance [4] [7] [8].
  • Coverage boundary: receptor/synaptic regulation is biologically relevant but is not owned by any retained child PM [3].
  • Evidence boundary: regional GABA/Glx concentrations are not synthesis flux, transporter activity or a direct circuit-level E/I measurement [1] [5] [9].

2. Primary Biological Effects​

Support GABA synthesis capacity; support glutamate signal termination/recycling; limit receptor-overload bioenergetic harm in defined contexts. These do not establish uniformly increased inhibition or comprehensive E/I regulation.

4. Mechanistic Basis (Integrated FM Narrative)​

4.1 Functional Rationale​

GABA synthesis, glutamate clearance/recycling and protection against excessive receptor stimulation contribute to a stable excitatory–inhibitory environment. Receptor and synaptic regulation remain outside the retained PM coverage.

4.2 Evidence Summary​

Enzyme evidence establishes PLP-dependent GABA synthesis and distinguishes basal from recruitable capacity. Reviews establish uptake/recycling as glutamate-termination steps. Chronic receptor-stimulation experiments demonstrate bioenergetic injury and bounded protection by magnesium sulfate. [4, 7, 8]

If these capacities function adequately, they would support transmitter supply, signal termination and resistance to excessive stimulation. Their aggregation does not directly measure circuit-level excitation–inhibition matching or cover every receptor and synaptic process that determines it; transmitter concentrations cannot stand in for those processes.

4.3 Suboptimal Function & Its Effects​

Constrained synthesis can reduce available inhibitory transmitter capacity; impaired clearance can prolong extracellular excitatory signalling [4] [7]. Sustained excessive receptor stimulation can impose bioenergetic harm in the assessed experimental setting [8]. These are different consequences and need not occur together. Transmitter concentrations alone cannot identify which capacity is constrained [9], and this inventory cannot diagnose unassessed receptor or synaptic regulation.

5. Connected Mechanisms​

7. Phenome Connections​

These outcomes describe translational contexts for the FM as an integrated biological capacity. They are not single-mechanism treatment claims. FM confidence uplift: FM confidence may exceed that of any individual child PM only where multiple PMs converge on the same phenome and the integrated FM biology provides additional biological rationale (biological uplift) beyond the individual mechanisms.

Biological convergence is a rationale for independent outcome assessment, not an automatic increase in evidence confidence. Existing FM ratings were not reassessed during PM8 retirement; no PM8 rating was transferred.

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8. References​