Peptides >TRH Thyrotropin (Protirelin)

TRH Thyrotropin (Protirelin)

Thyrotropin-releasing hormone (TRH), also known as protirelin, is a small peptide hormone that originates in the hypothalamus. Research on TRH has demonstrated its capacity to enhance thyroid function and has revealed its antidepressant and anti-suicidal properties. Moreover, TRH has been investigated for its potential advantages in various areas, including the aging process, regulation of feeding behavior, reduction of free radicals, and modulation of the autonomic nervous system.

This PRODUCT IS INTENDED AS A RESEARCH CHEMICAL ONLY. This designation allows the use of research chemicals strictly for in vitro testing and laboratory experimentation only. All product information available on this website is for educational purposes only. Bodily introduction of any kind into humans or animals is strictly forbidden by law. This product should only be handled by licensed, qualified professionals. This product is not a drug, food, or cosmetic and may not be misbranded, misused or mislabled as a drug, food or cosmetic.


1. TRH Overview


2. TRH Structure


3. TRH Research

Thyrotropin Releasing Hormone (TRH) Overview (also know as Protirelin)

TRH, often known as Protirelin, is a compact peptide hormone that originates in the hypothalamus. Its primary functions include triggering the release of thyroid-stimulating hormone and prolactin from the anterior pituitary gland. In clinical practice, TRH is utilized to assess the functioning of the anterior pituitary gland when investigating thyroid-related disorders. Scientific research suggests that TRH possesses antidepressant and anti-suicidal properties. Furthermore, it is likely involved in regulating various physiological processes such as aging, arousal, feeding behavior, autonomic regulation, and combating the damage caused by free radicals.

TRH Structure

Sequence: Pyr-His-Pro
Molecular Formula: C16H22N6O4
Molecular Weight: 362.39 g/mol
PubChem CID: 638678
CAS Number: 24305-27-9
Synonyms: Protirelin, Thyroliberin, Lopremone, Relefact

TRH Research

TRH and Depression:

Thyrotropin-releasing hormone (TRH) has garnered attention for its potential antidepressant effects. Research on TRH’s antidepressant properties dates back to at least the 1970s. In early studies, TRH was administered directly into the spines of patients with severe depression. Results showed that five out of eight patients responded favorably, experiencing a 50% or greater reduction in depressive symptoms and a significant decrease in suicidal thoughts. However, the short half-life of TRH limited the duration of these positive effects.

Further research extended these findings to depressed women, where TRH was again effective, particularly in those with a specific type of depression devoid of anxiety symptoms. The specific effects of TRH on depression appeared to be influenced by a patient’s emotional state.

To make TRH more practical for depression treatment, studies explored intravenous (IV) administration. TRH was found to cross the blood-brain barrier, making IV administration just as effective as intrathecal administration (spinal injection). However, IV administration is not a convenient option for most people, prompting research into developing an intranasal TRH-based nasal spray to treat depression more conveniently.

Interestingly, research on bipolar patients revealed that TRH had more profound effects on depression when administered at night. Nocturnal administration aligned better with the natural circadian rhythm of TRH, resulting in antidepressant effects that lasted up to 48 hours, a significant extension compared to other studies. Prolonged action via nocturnal administration could make TRH a practical and injectable treatment option for depression.

TRH Research and Motor Memory:

Motor memory, also known as muscle memory, pertains to the development of procedural memory through repetitive motor tasks, such as typing, riding a bicycle, or playing a musical instrument. It differs from rote memory, which involves memorizing facts, and is primarily encoded in the cerebellum, a region of the hindbrain responsible for motor control, coordination, equilibrium, and posture.

Studies in mice lacking the TRH gene have shown that they exhibit slower learning of specific motor tasks. However, the administration of exogenous TRH can enhance the speed of motor learning. These findings support the idea that TRH plays a role in facilitating motor learning and suggest that it is active in the cerebellum, where it contributes to the development of motor memory.

TRH and Cerebellar Diseases:

Additional research in mice has indicated that supplementation with thyrotropin-releasing hormone (TRH) may help mitigate the effects of diseases that impact the cerebellum. Specifically, TRH and TRH analogues have demonstrated the ability to reduce ataxia in models of human cerebellar degenerative diseases. This effect is believed to occur both directly, through the improvement of motor learning, and indirectly, by increasing arousal and reducing the impact of depression.

TRH Research for Opioid Overdose:

Opioids, including substances like heroin and Oxycontin, can be life-threatening in cases of overdose due to their suppression of the respiratory drive in the brainstem. Naloxone (Narcan) is the primary treatment for opioid overdose, effectively reversing respiratory suppression but also blocking the pain-controlling effects of opioids. This can pose a challenge for individuals with chronic pain.

New research conducted in rodents has demonstrated that TRH can increase both blood pressure and breathing rate. When administered intravenously or sprayed directly into the lungs, TRH dose-dependently elevated breathing rates without affecting pain control. Notably, TRH prevented death in all animals it was administered to. These findings suggest that TRH could become an important tool in combating opioid overdose, offering the same benefits as naloxone with fewer side effects. Moreover, TRH and naloxone appear to operate through different mechanisms, potentially allowing them to be used together or sequentially if needed.

TRH Analogue in Trauma:

Taltirelin, a more metabolically stable version of TRH with a longer half-life, has been tested in rats with acute hemorrhagic shock. Preliminary results have shown that TRH can improve mean arterial blood pressure and respiratory rate, similar to existing treatments for acute blood loss. TRH also improved blood pH and prevented a decrease in arterial oxygen saturation. These findings suggest that TRH could serve as a valuable adjunctive treatment for hypovolemic shock and acute blood loss, particularly in emergency medical settings.

TRH in Disease Development:

Changes in TRH levels have been associated with thyroid disease, but alterations in TRH and other thyroid hormones have also been observed in various non-thyroidal illnesses. Research in rats has indicated that specific neurons in the brain may be responsible for this phenomenon as they lose the ability to produce TRH and respond to feedback mechanisms. This has prompted interest in investigating whether TRH supplementation could reduce the severity of non-thyroidal illnesses and act as a complementary therapy alongside more targeted treatments.

TRH and the Aging Process:

Studies in mice have suggested that TRH may protect certain organs against oxidative damage and the effects of aging. TRH appears to reduce the accumulation of amyloid plaque in the kidneys, a common factor contributing to reduced kidney function with age. By preventing this plaque buildup, TRH may help preserve kidney function as individuals age. Similar protective effects have been observed in the testes of aging male mice.

Researchers are also exploring whether TRH can prevent amyloid plaque buildup in the brain, a hallmark of Alzheimer’s disease (AD). Initial studies in mice have produced mixed results, with TRH appearing to increase arousal in aging mice but unclear effects on amyloid plaque. However, it is worth noting that TRH levels drop in the hippocampus of AD patients, suggesting that supplementation may be beneficial even if it does not directly impact amyloid plaque buildup. Researchers are interested in understanding how TRH regulates the activity of various proteins in the hippocampus, potentially playing a role in AD pathogenesis.

Note: Thyrotropin-releasing hormone (TRH) is available for research purposes only and should not be used for human consumption unless by licensed researchers.


Article Author

The above literature was researched, edited and organized by Dr. Logan, M.D. Dr. Logan holds a doctorate degree from Case Western Reserve University School of Medicine and a B.S. in molecular biology.


The product information featured on this website pertains exclusively to in-vitro studies. In-vitro studies, also known as ‘in glass’ studies, are conducted outside of living organisms. It’s important to emphasize that these products do not constitute medicines or drugs and have not received FDA approval for the prevention, treatment, or cure of any medical conditions, ailments, or diseases. It is crucial to note that the introduction of these products into the bodies of humans or animals is strictly prohibited by law.