Oxytocin receptor

The oxytocin receptor (OTR) is a G protein-coupled receptor (GPCR) that binds the hormone oxytocin. It plays a crucial role in various physiological processes, including labor, lactation, and social bonding. The receptor is encoded by the OXTR gene in humans and is expressed in various tissues, including the uterus, mammary glands, and certain regions of the brain.

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Evolutionary tree of the oxytocin receptor.

Structure

The oxytocin receptor is a member of the class A family of GPCRs. It consists of seven transmembrane domains, an extracellular N-terminus, and an intracellular C-terminus. The receptor undergoes conformational changes upon binding to oxytocin, which activates intracellular signaling pathways.

Function

The primary function of the oxytocin receptor is to mediate the effects of oxytocin. In the uterus, it facilitates uterine contractions during labor. In the mammary glands, it promotes the milk ejection reflex during breastfeeding. In the central nervous system, the receptor is involved in modulating social behaviors, stress responses, and emotional regulation.

Signaling Pathways

Upon activation by oxytocin, the oxytocin receptor primarily couples with the Gq/11 protein, leading to the activation of phospholipase C (PLC). This results in the production of inositol trisphosphate (IP3) and diacylglycerol (DAG), which increase intracellular calcium levels and activate protein kinase C (PKC), respectively. These signaling events lead to the physiological responses associated with oxytocin.

Clinical Significance

The oxytocin receptor is a target for therapeutic interventions in various conditions. Agonists and antagonists of the receptor are being explored for their potential in treating preterm labor, autism spectrum disorders, and anxiety. Variations in the OXTR gene have been associated with differences in social behavior and susceptibility to certain psychiatric conditions.

Evolution

The oxytocin receptor has evolved across different species, reflecting its diverse roles in reproduction and social behavior. The evolutionary tree of the oxytocin receptor shows its conservation and divergence among various vertebrates, highlighting its importance in physiological processes.

Related Pages

• Oxytocin
• G protein-coupled receptor
• Labor (childbirth)
• Lactation
• Social bonding