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PubMed2001

Epidermal growth factor and 1alpha,25-dihydroxyvitamin D3 suppress lipogenesis in hamster sebaceous gland cells in vitro.

We have previously reported the establishment of a culture system of hamster auricular sebocytes. Although their morphologic and biochemical properties are very similar to those of human sebocytes, the regulation of lipogenesis is not clear. Therefore, we investigated the effect of epidermal growth factor, all-trans retinoic acid, 1alpha,25-dihydroxyvitamin D3, and androgens such as testosterone and 5alpha-dihydrotestosterone on lipogenesis in cultured hamster sebocytes. Intracellular lipid droplets detected with Oil-Red-O staining were observed in 5 d cultures and increased in a time-dependent manner; 40.7% +/- 1.11% of 2 wk cultured cells tested lipid-positive by flow cytometric analysis. When the hamster sebocytes were cultured in the presence of epidermal growth factor, all-trans retinoic acid, or 1alpha,25-dihydroxyvitamin D3, the intracellular lipid droplets were diminished by all-trans retinoic acid and epidermal growth factor, and slightly by 1alpha,25-dihydroxyvitamin D3. The intracellular lipid droplets consisted mainly of triglycerides (71.8%) and, as minor components, cholesterol (18.0%), wax esters (3.6%), and free fatty acids (6.6%). Epidermal growth factor and all-trans retinoic acid decreased the intracellular accumulation of triglycerides (92.6% and 96.1% inhibition, respectively) and free fatty acids (54.3% and 62.6% inhibition, respectively) in the sebocytes. In addition, 1alpha,25-dihydroxyvitamin D3 decreased the triglyceride level (34.3% inhibition), but augmented the accumulation of wax esters (30% increase). There was no difference in the level of cholesterol as a result of these treatments, however. In contrast, 5alpha-dihydrotestosterone augmented the formation of intracellular lipid droplets along with an increase in the accumulation of triglycerides in hamster sebocytes. Our findings that regulation of lipogenesis by all-trans retinoic acid and androgen in hamster sebocytes is identical to regulation in humans suggest that hamster sebocytes are useful for the elucidation of sebaceous function at the cellular level. Furthermore, this is the first evidence that epidermal growth factor and 1alpha,25-dihydroxyvitamin D3 may act as suppressors in the regulation of lipogenesis in hamster sebocytes in vitro.

Animals↗
PubMed1977

Characterization and hormonal control of the androgen receptor in the hamster sebaceous glands.

The costovertebral organs [CVO] and seminel vesicles [SV] of the hamster exhibit high saturable androgen uptake. The physicochemcal characteristics of the cytoplasmic androgen receptor present in these tissues have been determined and compared to those obtained in rat prostate[P]. Using the synthetic androgen R 1881 [methyltrienolone] as a radioactive ligand, it has been shown that the affinity of this compound for the cytosol CVO receptor [Kd = 0.7 +/- 0.1 nM] is similar to that for the crytosol SV receptor [Kd = 2.4 +/- 0.9 nm] in hamsters and the cytosol P receptor [Kd = 0.6 +/- 0.1 nM] in rats. The hormonal specificity of binding in these tissues is restricted to androgens. Moreover, testosterone and dihydrotestosterone have the same relative binding affinity in CVO and SV compared to R 1881. Following castration, the total number of androgen sites, as measured by an exchange assay with R 1881, decreases rapidly and parallels with a fall in lipogenic activity. Administration of an androgen rapidly restores binding capacity.

Animals↗
PubMed1984

Simultaneous assessment of fetal lung maturity and sebaceous gland function by gas chromatography.

Lipid profiles were analysed by gas chromatography of underivatised extracts from pellets and supernatant fractions of amniotic fluid (AFP and AFS). Peaks, identified as diglycerides resulting from on column decomposition of phosphoglycerides at high temperature, were obvious in gas chromatograms of AFS. The C32 diglyceride, mainly derived from dipalmityl lecithin, was not a prominent peak in AFS from pregnancies from which babies subsequently developed respiratory distress syndrome. There was evidence of a moderate increase of squalene in AFS and AFP for 10 pregnancies of 36-38 weeks gestation resulting in the birth of small for gestational age babies. The increase was not obvious for 21 out of 22 control pregnancies delivering appropriate for gestational age babies. This demonstrated that we had an assessment of two fetal functions in one chromatographic run, the ratio of C32/C34 diglycerides providing a measure of lung maturity and squalene providing an index of proximity to term or of the presence of intrauterine growth retardation.

Amniotic Fluid↗
PubMed2003

13-cis-retinoic acid competitively inhibits 3 alpha-hydroxysteroid oxidation by retinol dehydrogenase RoDH-4: a mechanism for its anti-androgenic effects in sebaceous glands?

Retinol dehydrogenase-4 (RoDH-4) converts retinol and 13-cis-retinol to corresponding aldehydes in human liver and skin in the presence of NAD(+). RoDH-4 also converts 3 alpha-androstanediol and androsterone into dihydrotestosterone and androstanedione, which may stimulate sebum secretion. This oxidative 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) activity of RoDH-4 is competitively inhibited by retinol and 13-cis-retinol. Here, we further examine the substrate specificity of RoDH-4 and the inhibition of its 3 alpha-HSD activity by retinoids. Recombinant RoDH-4 oxidized 3,4-didehydroretinol-a major form of vitamin A in the skin-to its corresponding aldehyde. 13-cis-retinoic acid (isotretinoin), 3,4-didehydroretinoic acid, and 3,4-didehydroretinol, but not all-trans-retinoic acid or the synthetic retinoids acitretin and adapalene, were potent competitive inhibitors of the oxidative 3 alpha-HSD activity of RoDH-4, i.e., reduced the formation of dihydrotestosterone and androstandione in vitro. Extrapolated to the in vivo situation, this effect might explain the unique sebosuppressive effect of isotretinoin when treating acne.

Alcohol Oxidoreductases↗
PubMed1982

The response of the sebaceous glands of female rats ovariectomized at birth to testosterone.

Newborn Sprague-Dawley rats were ovariectomized within 24 h of birth and control animals were sham-operated. Immediately, one-half of the rats in each group received a single injection of 500 micrograms testosterone propionate. The other half acted as a vehicle control. Normal male and female rats were also included for comparison. The secretion rate of sebum was measured at the age of 80 days from the amount of skin-surface lipids that could be extracted with acetone and which had been produced during 2 days. Male rats secreted more sebum than female rats. In female rats, irrespective the presence or absence of ovaries, when treated with a single injection of testosterone propionate at birth, although secreted significantly more sebum than vehicle control groups, the increase was still far below the level normally found in the male. On the other hand, implantation of testosterone pellet at the age of 4 weeks in neonatally ovariectomized-androgenized female rats greatly increased sebum secretion to an extent far exceeding that of the normal male rats. It is concluded that testosterone can directly increase sebum secretion in the female rats irrespective the presence or absence of ovaries when given at birth and reinforcement at about puberty produces a full effect of secretion.

Animals↗
PubMed1981

Sebaceous gland differentiation: III. The uses and limitations of freshly isolated mouse preputial gland cells for the in vitro study of hormone and drug action.

The effects of selected hormones and drugs on freshly isolated mouse preputial gland cells have been studied. The steroid hormones, testosterone, DHT, androstanediol, androsterone and androstanedione all failed to stimulate, and estradiol failed to inhibit, either DNA or lipid synthesis under the conditions studied. Thyroxine and insulin had no effect on lipogenesis but epinephrine and PGE2 caused significant stimulation as did Bt2cAMP. The antilipemic drugs clofibrate, nicotinic acid and hydroxycitrate were all able to inhibit lipogenesis. Of the anti-acne drugs only L-DOPA was able to inhibit lipogenesis, neither tetracycline nor trans-retinoic acid showed any effect. Pyridoxine was unable to inhibit lipogenesis but DMSO caused dramatic stimulation though it was without effect on DNA synthesis. Evidence is presented which suggests that the lack of response to steroid hormones is not due to the inability of the cells to take up and metabolize the steroids but is due to the fact that the time-span of exposure is not long enough to elicit a cellular response. It is concluded that these freshly isolated cells are suitable for the study of those effects of hormones and drugs which occur within the first 3 hr after exposure to the compound.

Androgens↗
PubMed1984

Peroxisomes in sebaceous glands. V. Complex peroxisomes in the mouse preputial gland: serial sectioning and three-dimensional reconstruction studies.

The ultrastructure of peroxisomes in partially differentiated cells of the mouse preputial gland was investigated using serial thin sections and three-dimensional reconstruction as well as the alkaline diaminobenzidine technique for visualization of the peroxidatic activity of catalase. An analysis of serial sections indicates that the different types of intensely stained peroxisomal profiles, classified according to their shape, represent random planes through highly complex peroxisomes. These organelles exceed 4 micron in length and exhibit a focal heterogeneity with respect to their size, shape and enzyme distribution. The graphical three-dimensional reconstruction demonstrates that the most intricate peroxisomes are characterized by tortuous, elongate, and branched tubular segments of varying diameter equipped with enlarged terminal hollow-spherical structures which engulf areas of cytoplasm. A close spatial relationship is established between adjacent peroxisomes and peroxisomes and mitochondria, the latter two of which synchronously develop into highly complex structures. A close association is also observed between peroxisomes and the endoplasmic reticulum, whereby membrane continuities between the two compartments cannot be demonstrated. These observations are inconsistent with traditional concepts concerning peroxisomal shape and size, the number per cell, as well as their biogenesis from the endoplasmic reticulum. The functional significance of individual highly complex peroxisomes and their assemblage forming an extensive net-like membraneous system throughout the cell is discussed with respect to intracellular energy transport and transmembrane electron exchange.

Animals↗
PubMed1994

Androgens affect the activity of human sebocytes in culture in a manner dependent on the localization of the sebaceous glands and their effect is antagonized by spironolactone.

To investigate the varying response of the pilosebaceous unit to androgens functional studies were performed on the effects of testosterone and 5 alpha-dihydrotestosterone on cultured human sebocytes derived from different skin regions. In addition, the effect of spironolactone on the proliferation of androgen-stimulated human sebocytes derived from facial skin was evaluated. Testosterone (10(-11) to 10(-5) M), 5 alpha-dihydrotestosterone (10(-11) to 10(-5) M) and spironolactone (10(-12) to 10(-7) M) were added for 10 days as single substances or in combinations to human sebocytes in secondary culture maintained in a serum-free medium. Cell proliferation was assessed using a fluorometric assay. Intracellular lipids were extracted from sebocytes treated with androgens (10(-7) M) for 10 days after confluency. Testosterone inhibited the proliferation of sebocytes derived from the legs with a 50%-inhibitory concentration at 10(-5) M and induced a 50% decrease of intracellular lipids. In contrast, 5 alpha-dihydrotestosterone stimulated the activity of leg sebocytes with a 50% increase of proliferation at 10(-5) M, and a 175% increase of intracellular lipids. On the other hand, the proliferation of facial sebocytes was significantly stimulated by testosterone with a 50%-stimulatory concentration at 10(-6) to 10(-5) M and mostly by 5 alpha-dihydrotestosterone with a 50% enhancement at 10(-8) to 10(-7) M. Spironolactone inhibited the proliferation of facial sebocytes in a dose-dependent manner with a 25%-inhibitory concentration at 10(-9) M. Simultaneous treatment of facial sebocytes with spironolactone and testosterone or 5 alpha-dihydrotestosterone resulted in decreased proliferation when compared to the growth obtained under androgens alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

The effect of sexual hormones on the lipid and proteinaceous secretion of the rat preputial sebaceous gland.

The diameters of Sudan Black B stained sebum vesicles and acid hematein stained perinuclear granules, and the numerical density of the latter, were determined in mature sebaceous preputial cells from normal male and female rats, testosterone-treated female rats and estradiol-treated male rats. Statistical analysis by Student's t-test showed that the diameter of lipid droplets was significantly higher in male than in female controls and that testosterone increased female values up to make control levels. Estradiol treatment decreased male values to levels below those of normal male and female controls and of testosterone-treated female rats. Diameters of perinuclear granules did not vary among animal groups but their numerical density was larger in testosterone treated than in normal female rats or estradiol treated male rats. Lipid droplet sizes and perinuclear granule numbers are thus increased by androgens and decreased by estrogens, which was interpreted an meaning that sexual hormones do not only act on sebaceous cell multiplication or turnover time as previously known, but also on the production of lipid and the output of beta-glucuronidase containing granules in this gland.

Animals↗
PubMed1992

Sebaceous gland lipids.

Human sebum contains squalene, wax esters, triglycerides, cholesterol esters, and possibly free cholesterol. The fatty acids of the ester lipids include species with chain branching or with unusual double-bond positions. The alcohol moieties of the wax esters contain unusual chain types similar to those of the fatty acids. Genetic and hormonal factors cause individual differences in sebaceous lipid composition. Genetic factors seem to influence the proportions of the various types of branched-chain fatty acids. Androgenic stimulation of the glands causes an increase in lipid synthesis, and therefore in the ratio of endogenously synthesized lipid to exogenous lipid. Because the endogenously synthesized lipids tend to be different from lipids that are derived exogenously, the overall composition of the secretion changes. Differences in sebum composition are particularly evident when the sebum of prepubertal children is compared with that of young adults. One difference that may be of clinical significance is the different concentrations of linoleate. Higher concentrations of sebum linoleate may protect young children from comedonal acne by preventing an essential fatty acid deficiency from developing in the follicular epithelium.

Fatty Acids↗
PubMed1984

Peroxisomes in sebaceous glands. III. Morphological similarities of peroxisomes with smooth endoplasmic reticulum and Golgi stacks in the circumanal gland of the dog.

In the canine circumanal gland, the morphological alterations of peroxisomes during differentiation and maturation of the glandular cells were studied by electron microscopy, cytochemistry and freeze-etch technique. Each of the following three cell types has its own characteristic peroxisomal population: 1) The basal cell contains only a few small peroxisomes, which appear as spherical and tubular profiles showing strong DAB reaction. In the differentiating basal cells, these are joined by a few dilated, hemispherical organelles with intensely stained small marginal plates. 2) In the intermediate cell, additional to spherical and tubular peroxisomes, numerous elongated organelles with distinct marginal plates are observed, displaying weak catalase activity. 3) In the mature cell, dumbbell-shaped peroxisomes with enlarged marginal plates predominate. Serial section analysis and freeze-etching studies reveal that these dilated particles are of erythrocyte-like shape. They exhibit very weak catalase activity or do not contain any visible DAB reaction product. In their flattened, thin central portions, the membranes enclose the marginal plates and form straight cisternae, which are closely associated with adjacent fenestrated cisternae of ER on both sides, referred to as paramarginal cisternae. Dumbbell-shaped peroxisomes with their corresponding paramarginal cisternae form large peroxisome-ER-complexes. Furthermore, three to five dumbbell-shaped particles are often stacked in parallel. Only at their flat poles are the organelles in close contact with paramarginal cisternae. The observation of continuities, in particular between erythrocyte-like organelles and tubular peroxisomes in mature glandular cells, indicates the existence of a peroxisomal compartment composed of two segments in the mature stage. In freeze-etch replicas of mature glandular cells, only the dilated segments of the peroxisomal compartment can be easily recognized because of their unusual size and erythrocyte-like shape. Additionally, on the E-face of their central portion, a straight, square or rectangular area with a distinct crystalline pattern is seen, which corresponds to the marginal plate. These findings indicate that the circumanal gland of the dog offers a unique possibility to analyze the biological properties of a well-defined peroxisomal compartment.

Animals↗