Negative-feedback control
Evidence context. Preclinical evidence.
Presynaptic α2 adrenoceptors can inhibit further norepinephrine release. Genetic and pharmacological evidence indicates an important role for α2A, with contributions from α2C in some preparations and activity regimes.
A receptor label does not imply identical function everywhere that receptor is expressed. Tissue, circuit, endogenous activity, and experimental method all affect the interpretation.
Functional heterogeneity
Evidence context. Preclinical evidence.
Projection-specific work in mouse locus coeruleus neurons suggests that somatodendritic α2-autoreceptor function can vary across neuronal populations. Receptor responses also depend on ligand, pathway, assay configuration, and timescale.
Aeviant treats subtype preference as one dimension in a broader assessment of the physiological state created by a drug.
Positive allosteric modulation and direct agonism
Evidence context. Established biology.
A direct agonist activates a receptor through its own pharmacology. A positive allosteric modulator is defined by its effect on the response to a specified orthosteric ligand, under specified experimental conditions. State dependence and intrinsic activity are separate pharmacological properties.
Ligand dependence, intrinsic agonism, subtype selectivity and signalling behaviour each require direct experimental measurement.
The AVX-1 research question
Evidence context. Program objective.
Aeviant’s hypothesis is that potentiating the α2A response to endogenous norepinephrine may help reinforce autoinhibitory feedback while preserving dependence on the endogenous signal.
The detailed pharmacology objectives and advancement criteria are published in the AVX-1 program dossier.
Limitations
α2A is not the only α2 autoreceptor subtype. Several foundational studies use mouse genetics, peripheral sympathetic preparations, or ex vivo tissue and should not be generalized directly to human central pharmacology.
Relevance to the current program
Aeviant is investigating whether positive allosteric modulation of α2A can potentiate the receptor’s response to endogenous norepinephrine while preserving dependence on that signal. Experimental pharmacology will determine the resulting activity profile.
Evidence records
The Evidence Library contains the source, relevance and limitations for each record used in this review.
- The α2A-adrenergic autoreceptor participates in negative-feedback regulation — Preclinical evidence.
- Locus coeruleus autoregulation may not be homogeneous — Preclinical evidence.
- α2A signalling has measurable time-dependent kinetics — Preclinical evidence.
- Positive allosteric modulation is defined relative to a specified orthosteric ligand and context — Established biology.
Further reading: Tonic and phasic signalling, the evidence library, and AVX-1.