THE PLACENTAL EXPRESSION OF WHICH ENZYME IS THOUGHT TO PROTECT THE FETUS FROM MATERNAL CORTISOL

• A. Aldosterone synthase
• B. 11β-Hydroxysteroid dehydrogenase (HSD)-1
• C. 11β-HSD-2 ✓
• D. 17α-Hydroxylase
• E. 11α-Hydroxylase

The enzyme thought to protect the fetus from maternal cortisol is 11β-Hydroxysteroid dehydrogenase (HSD)-2. This enzyme plays a crucial role in regulating the levels of cortisol in the placenta, preventing excessive exposure of the fetus to maternal cortisol which could have negative developmental effects.

11β-Hydroxysteroid dehydrogenase (HSD)-2 is responsible for converting active cortisol into its inactive form, cortisone, within the placental tissues. By doing so, it helps maintain a balanced environment for the developing fetus, shielding it from the potentially harmful effects of high levels of cortisol. This protective mechanism is essential for ensuring proper fetal development and growth during pregnancy.

In other words, the enzyme 11β-Hydroxysteroid dehydrogenase (HSD)-2 is thought to protect the fetus from maternal cortisol by inactivating it. This enzyme is primarily expressed in the placenta and acts as a barrier to prevent excessive exposure of the fetus to maternal cortisol, which could have detrimental effects on fetal development.

Mechanism of Action: 11β-Hydroxysteroid dehydrogenase (HSD)-2 functions by converting active cortisol into its inactive form, cortisone. By doing so, it reduces the amount of biologically active cortisol that can cross the placental barrier and reach the fetus. This mechanism helps maintain a balance in cortisol levels between the mother and the developing fetus.

Role in Fetal Development: Cortisol is a stress hormone that plays a crucial role in various physiological processes in both the mother and the fetus. However, excessive exposure to cortisol during pregnancy can lead to adverse outcomes for the developing fetus, such as impaired growth and neurodevelopmental issues. The presence of 11β-Hydroxysteroid dehydrogenase (HSD)-2 in the placenta helps regulate cortisol levels and protects the fetus from potential harm.

In conclusion, 11β-Hydroxysteroid dehydrogenase (HSD)-2 is the enzyme responsible for safeguarding the fetus from maternal cortisol by converting it into an inactive form, thereby preventing excessive exposure and maintaining a healthy environment for fetal development.