chewbaca
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Hormonal control of sebum
Sebum production is under the control of sex hormones (androgens). The most active androgens are testosterone, 5-testosterone (DHT) and 5-androstene-317diol. These hormones and others are made by the sex glands (ovary in females, testis in males) and by the adrenal gland. These glands are in turn under the influence of the pituitary gland, located in the brain.
Androgens are made more active by enzymes in the skin and sexual organs. Type 1 5- reductase acts in the skin and Type II 5- reductase acts in the sexual organs. These enzymes convert less active androgens into the active testosterone and 5-testosterone (DHT). These more active androgens stimulate sebaceous gland cells to produce more sebum.
The role of progesterone is unclear. Females produce more sebum in the week before their menstrual period when progesterone levels are higher. But progesterone is known to reduce the activity of the enzyme 5-reductase that one might expect to reduce sebum production.
Sebum varies with age
Sebaceous glands are already active before birth. They are regulated by the mothers hormones and those made by the fetus itself.
The composition of oils on the skin surface varies with age:
The fetus produces vernix caseosa, a waxy protective layer
For 3 to 6 months, sebum produced by a newborn baby resembles that of an adult
Thereafter until the age of 8 it has less wax and squalene and more cholesterol
Sebum production increases at puberty up to fivefold in men
Adult males produce slightly more sebum than adult females
Sebum production declines with age, particularly after menopause in females
The amount of sebum can be altered by disease:
Pituitary, adrenal, ovarian or testicular disorders may increase or reduce it
Prolonged starvation reduces the amount of sebum
Parkinson's disease increases the amount of sebum
The amount can be reduced by certain systemic medications:
Oestrogens (oral contraceptive pill)
Antiandrogens such as cyproterone acetate and spironolactone
Vitamin-A derivatives such as isotretinoin
The amount can be increased by other systemic medications:
Testosterone given to prepubertal males
Progesterones with androgenic properties such as medroxyprogesterone, levonorgestrel
Phenothiazines
The proportion of different components may change with certain medications:
Diane-35® / Estelle-35® (ethinyl oestradiol 35mcg, cyproterone 2mg) increases linoleate
Isotretinoin reduces squalene, wax esters and fatty esters
Sebum production is under the control of sex hormones (androgens). The most active androgens are testosterone, 5-testosterone (DHT) and 5-androstene-317diol. These hormones and others are made by the sex glands (ovary in females, testis in males) and by the adrenal gland. These glands are in turn under the influence of the pituitary gland, located in the brain.
Androgens are made more active by enzymes in the skin and sexual organs. Type 1 5- reductase acts in the skin and Type II 5- reductase acts in the sexual organs. These enzymes convert less active androgens into the active testosterone and 5-testosterone (DHT). These more active androgens stimulate sebaceous gland cells to produce more sebum.
The role of progesterone is unclear. Females produce more sebum in the week before their menstrual period when progesterone levels are higher. But progesterone is known to reduce the activity of the enzyme 5-reductase that one might expect to reduce sebum production.
Sebum varies with age
Sebaceous glands are already active before birth. They are regulated by the mothers hormones and those made by the fetus itself.
The composition of oils on the skin surface varies with age:
The fetus produces vernix caseosa, a waxy protective layer
For 3 to 6 months, sebum produced by a newborn baby resembles that of an adult
Thereafter until the age of 8 it has less wax and squalene and more cholesterol
Sebum production increases at puberty up to fivefold in men
Adult males produce slightly more sebum than adult females
Sebum production declines with age, particularly after menopause in females
The amount of sebum can be altered by disease:
Pituitary, adrenal, ovarian or testicular disorders may increase or reduce it
Prolonged starvation reduces the amount of sebum
Parkinson's disease increases the amount of sebum
The amount can be reduced by certain systemic medications:
Oestrogens (oral contraceptive pill)
Antiandrogens such as cyproterone acetate and spironolactone
Vitamin-A derivatives such as isotretinoin
The amount can be increased by other systemic medications:
Testosterone given to prepubertal males
Progesterones with androgenic properties such as medroxyprogesterone, levonorgestrel
Phenothiazines
The proportion of different components may change with certain medications:
Diane-35® / Estelle-35® (ethinyl oestradiol 35mcg, cyproterone 2mg) increases linoleate
Isotretinoin reduces squalene, wax esters and fatty esters
