TRH GPCR Assays

Background of TRH Receptors

Thyrotropin-releasing hormone (TRH) is a tripeptide pyroGlu-His-Proamide generated from the hypothalamus. TRH receptors are G protein-coupled receptors activated by TRH, exerting a profound influence on the central nervous system (CNS). The studies of TRH receptors in humans are still limited to date.

Fig.1 Thyrotropin-releasing hormone signaling. (Hinkle, 2012)

Distributions and Functions of TRH Receptors

TRH receptors are distributed in the brain, pituitary gland, and eye. They are involved in many biological activities, such as the stimulation of prolactin and thyrotropin releases. TRH₁ receptors have been demonstrated to participate in taltirelin actions in the mouse CNS and regulation of depression and anxiety-like behaviors.

Subtypes and Mechanisms of TRH Receptors

There is only one subtype of TRH GPCR in humans. The signal transduction of TRH₁ receptors is mediated by G_q/G₁₁ proteins.

Receptor	Gene	Mechanism	Agonists	Antagonists
TRH₁ receptor	TRHR	TRH₁ receptor is activated by TRH TRH₁ receptor couples to G_q/G₁₁ protein, stimulating phospholipase C Activation of the TRH₁ receptor stimulates PIP₂ hydrolysis to form IP₃ and DG The secondary messengers of TRH₁ receptor activation stimulate calcium/calmodulin-dependent protein kinase and mitogen-activated protein kinase.	[³H]MeTRH MeTRH taltirelin	midazolam chlordiazepoxide

Assay List of TRH Receptor

Creative Biolabs can provide a range of assays of the TRH receptor. You can choose the assay in the list or contact us for more information:

TRHR

Assay No.	Assay Name	Host Cell	Assay Type	Datasheet
IP1 Assay
S01YF-1122-KX973	Magic™ Human TRHR In Vitro IP1 Assay	CHO-K1	IP1 Assay

Published Data

Paper Title	Taltirelin is a superagonist at the human thyrotropin-releasing hormone receptor.
Journal	Frontiers in Endocrinology
Published	2012
Abstract	Taltirelin (TAL) is a thyrotropin-releasing hormone (TRH) analog. In this study, the researchers characterized TAL binding to the TRH receptor in a model cell system. They also detected the signaling by the human TRH receptor in intact HEK-EM 293 cells stably expressing TRH-Rs. They examined the motor behavior of both TRH receptors and dopamine D2 receptors following 2 weeks of treatment in rats. The study has described the characterization of the pharmacology of TAL at the TRH receptor.
Result	The results have demonstrated that TAL exhibited lower binding affinities than TRH and lower signaling potency through the inositol-1,4,5-trisphosphate/calcium pathway than TRH. The EC₅₀ values for IP1 production were found to be 150 nM for TAL and 3.9 nM for TRH. However, TAL showed higher intrinsic efficacy than TRH in stimulating inositol-1,4,5-trisphosphate second messenger generation. the results suggested that TAL was a superagonist when signaling at TRH-R via the G_q/11 protein-phospholipase C-phosphatidylinositol-4,5-bisphosphate-inositol-1,4,5-trisphosphate-calcium pathway. TAL may play a role in mediating CNS effects in humans via its metabolic stability and ability to cross the blood-brain barrier. Fig.2 TAL and TRH binding and signaling via Ca²⁺ in cells expressing TRH-Rs. (Thirunarayanan, 2012)

References

Hinkle, P. M.; et al. Desensitization, trafficking, and resensitization of the pituitary thyrotropin-releasing hormone receptor. Frontiers in neuroscience. 2012, 6: 180.
Thirunarayanan, N.; et al. Taltirelin is a superagonist at the human thyrotropin-releasing hormone receptor. Frontiers in Endocrinology. 2012, 3: 120.

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