🔴 Mechanism of Action 🔴

🔺 Oxytocin :- It is a nonpeptide secreted from posterior pituitary along with Argenine Vasopressin (AVP or ADH) .

🔺Actions :-

1. Uterus :- Oxytocin increase the force and frequency if uterine contractions and basal tone increases only with high doses.

🔸Mechanism :- Oxytocin bind with G-protein coupled receptors located on myometrium which mediate response mainly depolarization of muscle fibres and influx of CALCIUM ions as well as through phosphoinositide hydrolysis and IP3 ( ionositol triphosphate) mediated intracellular release of CALCIUM ions.

Oxytocin also increase the PG (prostaglandin) synthesis and release by endometrium which may contribute to the contractile response.

2. Breast :- Facilitate milking.

3.CVS :- Umbilical vessels closure at birth.

4.Kidney :- Exerts ADH (Antidiuretic hormone )like effect at high doses.

🔺Physiological Role:-

1. Induce Labour

2. Milk ejection reflex

3. Neurotransmission