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Tryptophan and Brain Disorders / Treatment of Major Depression · Journal article
Expert Opinion on Drug Discovery · August 19, 2026
Raises a question worth testing. It does not answer one.
This is a narrative literature review of animal models used in depression research and antidepressant drug discovery. The authors identify five major biological domains implicated across multiple model types (HPA axis, neuroinflammation, monoamine/glutamate, neuroplasticity, and stress response) and argue that single-paradigm approaches may explain preclinical-to-clinical translational failure. The review does not present new empirical data but proposes that multimodal, endophenotype-driven strategies incorporating human data and sex differences would improve predictive validity.
Narrative literature review. Preclinical animal models of depression; implications for human depression research and antidepressant drug discovery..
No single animal model captures the complexity of depression; reliance on isolated paradigms may contribute to translational failure. Converging evidence across stress, developmental, genetic, neuroendocrine, immune, metabolic, and hormone-related models identifies shared pathophysiological domains: HPA axis dysregulation, neuroinflammation, monoaminergic and glutamatergic imbalance, and impaired neuroplasticity. Future progress depends on multimodal and endophenotype-driven approaches aligned with defined depression subtypes (inflammation-associated, hormone-sensitive, or stress-related).
Safety was not reported in the material analysed. Check the source before drawing any conclusion about harm.
This review provides conceptual framing for why current preclinical models may have limited predictive validity for human antidepressant efficacy. Clinicians and researchers should recognize that no single animal paradigm fully recapitulates depression pathophysiology and that integration of multiple biological mechanisms and human-relevant data is necessary to improve drug discovery.
A narrative review synthesizing preclinical animal model literature to identify biological mechanisms of depression and propose methodological improvements for drug discovery; raises questions about model validity and translational strategy rather than testing a clinical hypothesis.
As stated by the source record.
This review provides conceptual framing for why current preclinical models may have limited predictive validity for human antidepressant efficacy. Clinicians and researchers should recognize that no single animal paradigm fully recapitulates depression pathophysiology and that integration of multiple biological mechanisms and human-relevant data is necessary to improve drug discovery.
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
What is missing. This record has no reported figures. That is a gap in the analysis, not a judgement about the study.
INTRODUCTION: Depression is a heterogeneous and multifactorial condition with substantial unmet therapeutic need. Despite significant research, current pharmacotherapies remain limited in efficacy and onset, reflecting an incomplete understanding of underlying pathophysiology. Animal models have therefore been central to dissecting biological mechanisms and enabling antidepressant drug discovery. AREA COVERED: This review provides a synthesis of animal models of depression, including stress paradigms, developmental and genetic models, neuroendocrine manipulations, immune-based, metabolic and hormone-related models. PubMed was searched from database inception to March 2026 using depression-, species-, and model-specific terms. Each paradigm is evaluated in terms of face, construct, and predictive validity, with emphasis on relevance to drug discovery. Converging evidence across models highlights shared pathophysiological domains, including HPA axis dysregulation, neuroinflammation, monoaminergic and glutamatergic imbalance, and impaired neuroplasticity. EXPERT OPINION: No single model captures the complexity of depression; thus, reliance on isolated paradigms may contribute to translational failure. Future progress will depend on multimodal and endophenotype-driven approaches that align biological mechanisms with defined subtypes (e.g. inflammation-associated, hormone-sensitive, or stress-related depression). Integration of animal models with human-relevant data and sex-informed experimental design will advance precision psychiatry, improving predictive validity of preclinical antidepressant discovery.
Taken from the source record, never inferred. Follow any of these and new work involving them reaches your briefing.