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Differential effects of progestins on the circulating IGF-I system
Carlo Campagnoli1, Chiara Abbà, Simona Ambroggio
1Unit of Endocrinological Gynecology, Ospedale Ginecologico Sant'Anna, Azienda Ospedaliera OIRM-S, Anna, Corso Spezia 60, 10126 Torino, Italy. ginendocrinol@oirmsantanna.piemonte.it
Maturitas
|December 13, 2003
Summary
Hormone replacement therapy (HRT) impacts the insulin-like growth factor-I (IGF-I) system differently based on progestin type. Androgenic progestins can counteract estrogen-induced decreases in IGF-I levels.
Area of Science:
- Endocrinology
- Reproductive Medicine
- Metabolic Research
Background:
- Circulating insulin-like growth factor-I (IGF-I) is crucial for growth and metabolism, primarily produced by the liver under growth hormone (GH) influence.
- IGF-I bioavailability is tightly regulated by IGF-binding proteins (IGFBPs), with its production influenced by nutritional status and insulin levels.
- Menopause is associated with hormonal shifts that can affect the IGF-I system, and hormone replacement therapy (HRT) is often used to manage menopausal symptoms.
Purpose of the Study:
- To review existing data on how various hormone replacement therapy (HRT) regimens modify the circulating IGF-I system in menopausal women.
- To specifically examine the differential effects of various progestins, commonly used in HRT, on IGF-I and its binding proteins.
Main Methods:
- A comprehensive review of all published reports detailing the effects of different HRT formulations on the IGF-I system was conducted.
- Data synthesis focused on variations attributed to HRT administration route, estrogen dosage, baseline IGF-I levels, and specific progestin types.
Main Results:
- Hormone replacement therapy (HRT) exerts varied effects on the IGF-I system, influenced by administration route, estrogen dose, and progestin type.
- Estrogen replacement therapy (ERT) generally reduces circulating IGF-I, particularly with oral administration due to hepatic first-pass effects. This reduction is more pronounced in individuals with higher baseline IGF-I.
- Progestins with androgenic properties (e.g., 19-nortestosterone derivatives, medroxyprogesterone acetate) can mitigate the estrogen-induced decrease in IGF-I. Conversely, non-androgenic progestins (e.g., dydrogesterone) do not counteract this effect. Oral ERT significantly increases IGFBP-1 levels, an effect opposed by androgenic progestins. Data on IGFBP-3 and free IGF-I levels remain inconsistent.
Conclusions:
- Available evidence indicates that different progestins possess distinct effects on the circulating IGF-I system during HRT.
- The choice of progestin in HRT can modulate IGF-I levels and IGFBP-1, suggesting a potential for tailored therapeutic approaches.
- Further research is needed to fully elucidate the complex interactions within the IGF-I system under various HRT regimens, particularly concerning free IGF-I and IGFBP-3.