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Pick up to three peptides to see how their mechanisms, studied uses and evidence levels differ. Rows where the entries disagree are marked with a blue edge.
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Comparison
Protirelin (TRH)
Cognitive & neuro
Evidence level
Limited evidence
Approval status
Approved drug
Mechanism of action
- 1.Binds TRH receptors on the anterior pituitary, releasing thyroid-stimulating hormone.
- 2.Acts as a neuromodulator in the brain, influencing acetylcholine, dopamine and glutamate signalling.
- 3.Is broken down within minutes, which limits any sustained central effect.
- 4.Analogues were developed to resist that breakdown and cross into the brain better.
- 5.Raises prolactin in some situations, which is used diagnostically.
Studied for
- Thyroid and pituitary function testing (approved use)
- Amyotrophic lateral sclerosis
- Depression
- Spinocerebellar degeneration and cognitive impairment
Reported effects
- A rapid, measurable TSH rise in the diagnostic test
- Antidepressant and motor neurone trials showed inconsistent or transient effects
- Any cognitive benefit was not sustained in controlled studies
Side effects
- Nausea
- Flushing and a warm sensation
- Urgent need to urinate
- Dizziness
- Transient changes in blood pressure and heart rate
- Rare arrhythmia
Research protocol
Research context only - an approved diagnostic and an unsuccessful therapeutic. The diagnostic test uses 200 to 500 micrograms intravenously with TSH sampled at 20 to 30 minutes. Neuropsychiatric trials used repeated injections or infusions over days to weeks and did not produce durable benefit.
Research context only
Evidence justification
The diagnostic use is well established, but the cognitive and psychiatric claims come from mostly small, negative or inconsistent trials from the 1970s to 1990s.