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Metandienone Wikipedia

**Dihydrotestosterone (DHT)**
*(also called 5α‑dihydrotestosterone; abbreviation: DHT)*

> **Classification:** Anabolic–androgenic steroid (AAS) – a potent endogenous androgen derived from testosterone.

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## 1. Overview & Pharmacology

| Item | Details |
|------|---------|
| **Chemical nature** | Steroid hormone, C19H30O2; 5α‑reduced derivative of testosterone. |
| **Synthesis** | • **Testosterone → DHT**: 5α‑reductase (types I & II) converts testosterone to DHT.
• **Dihydrotestosterone → Androsterone** (via 3α‑hydroxysteroid dehydrogenase). |
| **Receptor affinity** | Binds androgen receptor (AR) with ~10× higher affinity than testosterone. |
| **Physiological actions** | • Drives male sexual development (genitalia, prostate, seminal vesicles).
• Regulates hair growth patterns.
• Influences secondary sex characteristics. |
| **Clinical relevance** | • Excess DHT → androgenic alopecia, benign prostatic hyperplasia.
• 5α‑reductase inhibitors reduce conversion of testosterone to DHT (finasteride). |

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## Key Pathway Highlights

1. **Steroidogenic Acute Regulatory Protein (STAR)** – essential for cholesterol transfer into mitochondria.
2. **P450scc (CYP11A1)** – converts cholesterol → pregnenolone in the inner mitochondrial membrane.
3. **Side‑chain cleavage** – final step of progesterone synthesis from pregnenolone, critical to maintain progesterone levels.
4. **Regulatory factors** – LH stimulates STAR expression; cAMP/PKA pathway activates key enzymes.
5. **Pathology** – defects in CYP11A1 or side‑chain cleavage lead to progesterone deficiency and reproductive disorders.

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### Quick Recap

| Step | Key Enzyme | Product |
|------|------------|---------|
| 1 | P450scc (CYP11A1) | Pregnenolone |
| 2 | 3β‑HSD | Progesterone |
| 3 | Side‑chain cleavage | Aldosterone, cortisol (if needed) |

Understanding these steps is essential for diagnosing and treating disorders of progesterone synthesis.