Inhibition of lipogenesis and sebum secretion for Lotus corniculatus seed extract in vitro and in vivo.

BACKGROUND: Botanical ingredients are widely used in hair- and skin-care products. However, few studies have investigated the effectiveness of botanical products on counteracting sebum synthesis and secretion. OBJECTIVE: To investigate the composition of Lotus corniculatus seed extract (LC) and its potential inhibition of lipogenesis in SZ95 sebocytes and oily human skin. METHODS: The active components of LC solutions were identified by high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). The in vitro effects of LC were evaluated using SZ95 cells treated with linoleic acid (LA) and dihydrotestosterone (DHT) and incubated with LCs for 24 h and 72 h. Lipogenesis was assessed by Oil Red O and Nile Red staining of the cells. In vivo effects were assessed on 30 subjects with oily skin who were enrolled in a randomized, blank-controlled trial and were treated with LC solution for 6 h and 4 weeks. The skin sebum contents and area on the forehead and cheeks were evaluated using a Sebumeter SM815 and Sebfix sebutape with Visioscan VC98. In addition, VISIA was used to collect half-face photos for analysis. RESULTS: A novel active molecule, 5'-o-rhamnosyl uridine, was identified in LC. LC exhibited a dose-dependent inhibitory effect on LA and DHT-induced lipid synthesis. When 5% LC was applied for 3 h, the skin sebum contents and area were significantly reduced compared with the vehicle control, with an obvious reduction after 6 h. Continued use of the serum containing 5% LC for 4 weeks resulted in a significant reduction in the skin sebum contents and area. No adverse reactions were reported during the study. CONCLUSIONS: Topical application of LC resulted in an immediate and long-lasting reduction of the sebum contents and area of oily human skin by reducing sebaceous lipogenesis through the LA and DHT pathways. This indicates the potential of LC as a new biological treatment for oily skin.

CONTEXTE: Les ingrédients végétaux sont largement utilisés dans les produits de soins des cheveux et de la peau. Cependant, peu d'études ont examiné l'efficacité des produits végétaux dans l'inhibition de la synthèse et de la sécrétion de sébum. OBJECTIF: Étudier les composants de l'extrait de graines de lotus (LC) et son effet inhibiteur potentiel sur la lipogenèse des cellules sébacées SZ95 et de la peau grasse. MÉTHODES: Les composants actifs de la solution LC ont été identifiés par chromatographie liquide à haute performance (HPLC) et par résonance magnétique nucléaire (NMR). Les effets de la LC in vitro ont été évalués à l'aide de cellules SZ95 traitées à l'acide linoléique (LA) et à la dihydrotestostérone (DHT) et incubées avec la LC pendant 24 et 72 heures. Les effets in vivo ont été évalués chez 30 sujets à peau grasse qui ont participé à un essai contrôlé randomisé à blanc et qui ont été traités avec une solution de LC pendant 6 heures et 4 semaines. Le sebumeter SM815 et le sebfix sebutape et le visioscan VC98 ont été utilisés pour évaluer la teneur en sébum et la surface de la peau sur le front et les joues. De plus, des photos de demi - visage ont été recueillies pour analyse à l'aide de VISIA. RÉSULTATS: Une nouvelle molécule active, 5'-o-rhamnosyluridine, a été identifiée dans la LC. La LC a un effet inhibiteur dose - dépendant sur la synthèse lipidique induite par LA et DHT. La teneur et la surface du sébum cutané ont été significativement diminuées par rapport à celles du support photographique après 3 heures d'application de 5% de LC, et significativement diminuées après 6 heures. L'utilization de sérum contenant 5% de LC pendant quatre semaines consécutives a entraîné une réduction significative de la teneur en sébum et de la surface de la peau. Aucun effet indésirable n'a été signalé au cours de l'étude. CONCLUSION: L'application topique de LC peut réduire la production de sébum par les voies LA et DHT, ce qui réduit immédiatement et durablement la teneur en sébum et la surface de la peau huileuse humaine. Cela démontre le potentiel de la LC en tant que nouveau traitement biologique de la peau huileuse.

Effect of antioxidant treatment with n-acetylcysteine and swimming on lipid expression of sebaceous glands in diabetic mice.

The sebaceous gland (SG) is involved in different inflammatory, infectious and neoplastic processes of the skin and can be related to specific diseases, e.g., diabetes mellitus. Sometimes, the histological diagnosis requires complementary tests due to the ability of diseases to mimic other tumors. We evaluated the sebaceous gland density in Non-obese diabetic mice to analyze the N-acetylcystein effects and swimming exercise treatment in sebaceous glands healing, using specific staining in histochemistry and immunohistochemistry reactions in the identification of the lipid expression in the sebaceous gland. We investigated the intracytoplasmic lipid expression and analysis of gland density from SG in dorsal skin samples from the Non-obese diabetic (NOD mice) and diabetic animals submitted to antioxidant treatment and physical exercise. For histological analysis of the sebaceous glands, specific staining in histochemistry with sudan black and immunohistochemistry reaction with adipophilin were used in the evaluation. Statistical analysis showed significant proximity between the values of the control group and the diabetic group submitted to the swimming exercise (DS group) and similar values between the untreated diabetic group (UD group) and diabetic group treated with the antioxidant N-acetylcysteine (DNa group), which did not prevent possible differences where p < 0.01. Adipophilin (ADPH) immunohistochemistry permitted more intense lipid staining in SGs, the preservation of the SG in the control group, and a morphological deformed appearance in the UD and DNa groups. However, weak morphological recovery of the SG was observed in the DS-Na group, being more expressive in the DS group. In conclusion, the groups submitted to physical exercises showed better results in the recovery of the analyzed tissue, even being in the physiological conditions caused by spontaneous diabetes.

Anti-sebum efficacy of guava toner: A split-face, randomized, single-blind placebo-controlled study.

BACKGROUND: Guava has benefit phytochemicals that are important for skin-disorder treatment. Nevertheless, its efficacy against oily skin has never been reported. AIMS: The guava toner was developed and clinical evaluated. METHODS: The base toner was formulated, accelerated stability tested, and sensory-evaluated in 10 volunteers. The highest preference base was incorporated with guava extract, stability examined, and skin irritation assessed in 21 volunteers by a single application close patch test. Anti-sebum efficacy was split-face, randomized, single-blind placebo-controlled evaluated in 21 volunteers for 28 days and monitored by Sebutape® on forehead and nose. RESULTS: The stable toner base with the greatest preference (83.20 ± 1.85%) was incorporated with 3%, 4.5%, and 6% of guava extract. The toners were stable with none of skin irritation. The toner with 6% guava extract was selected for efficacy evaluation. Guava toner significantly reduced oiliness of forehead (13.10 ± 3.67%, P < 0.05) and nose (21.43 ± 3.21%, P < 0.001) better than the base toner. The activity on nose was significantly noted (10.72 ± 3.51%, P < 0.05) since the 3rd week of application. CONCLUSIONS: Anti-sebum guava toner was efficiently evidence approved and suitable for a daily application to improve the efficacy.

The ameliorative effect of hemp seed hexane extracts on the Propionibacterium acnes-induced inflammation and lipogenesis in sebocytes.

In this study, we investigated the anti-microbial, anti-inflammatory, and anti-lipogenic effects of hemp (Cannabis sativa L.) seed hexane extracts, focusing on the Propionibacterium acnes-triggered inflammation and lipogenesis. Hemp seed hexane extracts (HSHE) showed anti-microbial activity against P. acnes. The expression of iNOS, COX-2, and the subsequent production of nitric oxide and prostaglandin increased after infection of P. acnes in HaCaT cells, however, upon treating with HSHE, their expressions were reduced. P. acnes-induced expressions of IL-1ß and IL-8 were also reduced. HSHE exerted anti-inflammatory effects by regulating NF-κB and MAPKs signaling and blunting the translocation of p-NF-κB to the nucleus in P. acnes-stimulated HaCaT cells. Moreover, P. acnes-induced phosphorylation of ERK and JNK, and their downstream targets c-Fos and c-Jun, was also inhibited by HSHE. In addition, the transactivation of AP-1 induced by P. acnes infection was also downregulated by HSHE. Notably, HSHE regulated inflammation and lipid biosynthesis via regulating AMPK and AKT/FoxO1 signaling in IGF-1-induced inflammation and lipogenesis of sebocytes. In addition, HSHE inhibited 5-lipoxygenase level and P. acnes-induced MMP-9 activity, and promoted collagen biosynthesis in vitro. Thus, HSHE could be utilized to treat acne vulgaris, through its anti-microbial, anti-inflammatory, anti-lipogenic, and collagen-promoting properties.

Polyphenol-rich apple extract inhibits dexamethasone-induced sebaceous lipids production by regulating SREBP1 expression.

Sebum production and excretion is a primary function of the sebaceous glands, but abnormally increased sebum production is a major cause of acne vulgaris. To identify a new candidate that regulates sebum production, we investigated the possible inhibitory effects of apple polyphenols (APP) purified from unripe apples on primary cultured human sebocytes and in patients with acne vulgaris. Dexamethasone (Dex) increased lipid synthesis and expression of the sterol response element-binding protein 1 (SREBP 1) and its target enzymes, acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), in the sebocytes. However, APP inhibited Dex-induced lipid production and expression of SREBP-1, ACC and FAS. APP also inhibited the increase in the expression and activation of glucocorticoid receptor in the sebocytes. Taken together, these results suggest that APP may be useful to regulate sebum production and may alleviate sebum-involved skin disease, such as acne vulgaris.

Inhibitory effect of imperatorin on insulin-like growth factor-1-induced sebum production in human sebocytes cultured in vitro.

AIMS: Acne is a common skin disease that originates in the sebaceous gland. The pathogenesis of acne is very complex, involving the increase of sebum production and perifollicular inflammation. In this study, we screened the anti-lipogenic material and demonstrated its effect using cultured human sebocytes. MAIN METHODS: Normal human sebocytes were cultured by explanting the sebaceous glands. To evaluate the anti-lipogenic effect, sebocytes were treated with test materials and (14)C-acetate incorporation assay was performed. KEY FINDINGS: To screen the anti-lipogenic materials, we tested the effect of many herbal plant extracts. We found that Angelica dahurica extract inhibited the insulin-like growth factor-1 (IGF-1)-induced sebum production in terms of squalene synthesis in sebocytes. Furthermore, imperatorin isolated from A. dahurica showed remarkable inhibitory effect on squalene production as well as squalene synthase promoter activity. To investigate the putative action mechanism, we tested the effect of imperatorin on intracellular signaling. The results showed that imperatorin inhibited IGF-1-induced phosphorylation of Akt. In addition, imperatorin significantly down-regulated PPAR-γ and SREBP-1, the important transcription factors for lipid synthesis. SIGNIFICANCE: These results suggest that imperatorin has a potential for reducing sebum production in sebocytes, and can be applicable for acne treatment.

Possible intermediary role of ghrelin in seborrhea.

Seborrhea, or oily skin, is a very common condition, especially among young people, caused by the increased secretion of sebum by sebaceous glands in the skin. Based on today's knowledge, a regulatory role of various hormones especially androgens is considered for sebaceous gland secretion; but despite significant evidences emphasis on the effects of the gastrointestinal disorders on coetaneous manifestations, the role of gastrointestinal problems in sebum secretion has not been emphasized yet. This study aimed to explain hormonal changes occurring in gastroesophageal reflux disease which may cause changes in sebaceous gland secretion so that, by explaining these communication mechanisms, common investigations between gastroenterology and dermatology can be performed to evaluate the accuracy of this hypothesis.

The clinical and histological effect of home-use, combination blue-red LED phototherapy for mild-to-moderate acne vulgaris in Korean patients: a double-blind, randomized controlled trial.

BACKGROUND: Blue and red light have been reported to have beneficial effects on acne. However, there has been no double-blind, randomized study of acne treatment for combined blue and red light-emitting diode (LED) devices, and the associated molecular mechanisms have rarely been investigated. OBJECTIVES: To evaluate the efficacy, safety and histological changes of combined blue and red LED phototherapy for acne vulgaris. METHODS: Thirty-five patients with mild-to-moderate acne were randomly assigned to either a home-use irradiation group using an LED device, or a control group using a sham device. The treatment group was instructed to serially irradiate their forehead and cheeks with 420-nm blue light and 660-nm red light for 2.5 min twice daily for 4 weeks. RESULTS: At the final visit at 12 weeks, both inflammatory and noninflammatory acne lesions had decreased significantly, by 77% and 54%, respectively, in the treatment group. No significant difference was observed in the control group. In the treatment group, sebum output reduction, attenuated inflammatory cell infiltrations and a decreased size of the sebaceous gland were found. The immunostaining intensities for interleukin (IL)-8, IL-1α, matrix metalloproteinase-9, toll-like receptor-2, nuclear factor-κB, insulin-like growth factor-1 receptor and sterol response element binding protein (SREBP)-1 were reduced concomitantly. Messenger RNA expression of SREBP-1c was also decreased. No severe adverse reactions were reported. CONCLUSIONS: This LED phototherapy was safe and effective for treating not only inflammatory but also noninflammatory acne lesions, with good compliance. The experimental results correlated well with clinical results, partly elucidating the related molecular mechanisms.

Testosterone synthesized in cultured human SZ95 sebocytes derives mainly from dehydroepiandrosterone.

Human sebaceous gland possesses all the steroidogenic enzymes required for androgen synthesis. It remains unclear whether the testosterone produced in situ mainly derives from circulating dehydroepiandrosterone (DHEA) or from de novo synthesis utilizing serum cholesterol. Using testosterone radioimmunoassay, we found that testosterone was barely detectable in the supernatant of cultured human SZ95 sebocytes when cholesterol was added alone, indicating a low basal expression of steroidogenic acute regulatory protein (StAR) in SZ95 cells. Human chorionic gonadotropin and fibroblast growth factor-9 were as potent as forskolin in activating StAR to enhance testosterone production, while interleukin-1 beta, dexamethasone, insulin and insulin-like growth factor-1 showed no stimulatory effect. A two-fold increase of testosterone production was observed in supplementation of DHEA as compared to pregnenolone, progesterone or 17 alpha-hydroxyprogesterone. Based on our findings, testosterone synthesized in cultured sebocytes derived mainly from DHEA and inhibition of 3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase may be a new target of androgen suppression for acne treatment.

Modulation of gonadotrophin-releasing hormone pulse generator activity by the pheromone in small ruminants.

In small ruminants, such as goats and sheep, a primer pheromone produced by males induces an out-of-seasonal ovulation in anoestrous females, a phenomenon known as the male effect. The male effect is unique in that an external chemical stimulus can immediately modulate the activity of the hypothalamic gonadotrophin-releasing hormone (GnRH) pulse generator. We have established a monitoring method of the GnRH pulse generator activity in Shiba goat. Using this method as a sensitive bioassay to assess the male effect pheromone activity, we have shown that the male effect pheromone is synthesised in an androgen-dependent manner in the sebaceous glands or their vicinity in specific body regions in goats. Although chemical identity of the pheromone is yet to be determined, analyses of male goat hair extracts by gas chromatography fractionation suggest that the male effect pheromone is a volatile substance with relatively small molecular weight. From morphological and molecular biological studies in goats, it is suggested that the pheromone molecule is detected by a member of the V1R family located on both the olfactory neurones and the vomeronasal sensory neurones, and the pheromone signal is conveyed to the medial nucleus of amygdala via the main olfactory and vomeronasal pathways and, subsequently, to the hypothalamic GnRH pulse generator to enhance its activity.

Malassezia globosa and restricta: breakthrough understanding of the etiology and treatment of dandruff and seborrheic dermatitis through whole-genome analysis.

Dandruff and seborrheic dermatitis (D/SD) share an etiology dependent upon three factors: sebum, microbial metabolism (specifically, Malassezia yeasts), and individual susceptibility. Advances in microbiological and analytical techniques permit a more detailed understanding of these etiologic factors, especially the role of Malassezia. Malassezia are lipid-dependent and demonstrate adaptation allowing them to exploit a narrow niche on sebum-rich skin. Work in our and our collaborators' laboratories has focused on understanding these adaptations by detailed analysis of biochemistry and gene expression. We have shown that Malassezia globosa and M. restricta predominate on dandruff scalp, that oleic acid alone can initiate dandruff-like desquamation, that M. globosa is the most likely initiating organism by virtue of its high lipase activity, and that an M. globosa lipase is expressed on human scalp. Considering the importance of M. globosa in D/SD (and the overall importance of commensal fungi), we have sequenced the M. globosa and M. restricta genomes. Genomic analysis indicates key adaptations to the skin environment, several of which yield important clues to the role Malassezia play in human disease. This work offers the promise of defining new treatments to D/SD that are targeted at changing the level or activities of Malassezia genes.

Clinical and instrumental study of the efficacy of a new sebum control cream.

BACKGROUND: Some botanical compounds are considered useful to reduce sebum production. Aim To evaluate the efficacy of a sebum control cream containing polyphenol-rich extract from saw palmetto, sesame seeds, and argan oil in subjects with oily facial skin. METHODS: The study was carried out during the winter months (January and February). A total of 20 healthy volunteers (9 male and 11 female, aged 17-50 years, 16 with oily skin and 4 with combined skin) were studied. The test product was applied twice daily to the face for a period of 4 weeks. A clinical assessment and instrumental measurements were done before and after the treatment period. Casual sebum level on the forehead and both cheeks was determined with a photometric device (Sebumeter). The quantity of sebum on the midforehead was determined using sebum collector foils (Sebufix), which were then evaluated with skin camera Visioscope and software SELS (Surface Evaluation of the Living Skin). A subjective evaluation questionnaire regarding the cosmetic characteristics, tolerance, and efficacy of the product was filled out by the volunteers at the end of study. RESULTS: The product was very well accepted by all the volunteers. A visible sebum-regulating efficacy was reported in 95% of them. After 4 weeks of treatment, the clinical assessment scores decreased by 33%. There was a significant reduction in the casual sebum level by 20% and area covered with oily spots by 42%. The number of active sebaceous glands remained unaltered. CONCLUSION: These results objectively and quantitatively show the efficacy of the sebum control cream tested to reduce the greasiness and improve the appearance of oily facial skin.

Peroxisome proliferator-activated receptor gamma1 (PPAR-gamma1) as a major PPAR in a tissue in which estrogen induces peroxisome proliferation.

Estradiol administration induces peroxisome proliferation and the production of 3-hydroxy fatty acid pheromones in the uropygial glands of the duck, but not in the goose gland, which does not produce such pheromones. We isolated a peroxisome proliferator-activated receptor (PPAR)gamma1 cDNA from a duck uropygial gland cDNA library. Northern blots revealed two transcripts, PPAR gamma1 and gamma2, and showed that PPAR gamma was expressed at higher levels than PPAR alpha in the uropygial gland of the duck. Although PPAR gamma2 was expressed in both duck and goose uropygial gland, PPAR gamma1 was expressed only in the duck gland, which responds to estrogen by peroxisome proliferation. In NIH 3T3 transfected cells, PPAR gamma1 was activated by peroxisome proliferators such as Wy-14643, clofibric acid and Ly-171883 causing induction of the target marker gene. By cotransfection with a plasmid containing alpha-cis-retinoic acid receptor RXR alpha, the induction increased up to 9-fold. These results suggest that PPAR gamma1 may be involved in peroxisome proliferation while PPAR gamma2 may be involved in lipid metabolism.

Adrenal steroid precursors exert potent androgenic action in the hamster sebaceous glands of flank organs and ears.

To assess the effect of the androgen precursors dehydroepiandrosterone (DHEA) and androstenedione (4-ene-dione) on androgen-sensitive parameters in the skin of the hamster, these two steroids were released from SILASTIC implants inserted sc into castrated male hamsters. The pigmented area of the flank organs, the size of the underlying sebaceous glands, [3H]thymidine incorporation into these sebaceous glands, and the size of the ear sebaceous glands were measured. The decrease in flank organ size caused by orchidectomy was partially reversed by DHEA and completely reversed by 4-ene-dione, testosterone (T), or dihydrotestosterone (DHT) implants. Similarly, the size of the sebaceous glands of the flank organs was reduced 88.1% by castration, whereas DHEA, 4-ene-dione, T, and DHT implants reversed the effect of orchidectomy. Orchidectomy also decreased the sizes of the sebaceous glands of the ears; DHEA, 4-ene-dione, T, and DHT implants increased their sizes to 50.6%, 81.9%, 91.6%, and 105.8% of the values found in intact hamsters, respectively. Parallel results were observed on the labeling of flank organ sebaceous glands with [3H]thymidine as well as on prostate weight. Serum concentrations of T and DHT became undetectable in castrated hamsters and were increased to intact or slightly elevated values in animals receiving implants of DHEA, 4-ene-dione, or T. The present results show that DHEA and 4-ene-dione are potent stimulators of androgen-sensitive parameters in the sebaceous glands of both the flank organs and ears in the hamster and illustrate the importance of extragonadal or peripheral intracrine formation of active steroids. It is suggested that the castrated hamster supplemented with adrenal precursor steroids is a good model that can closely mimic the human situation, where adrenal steroids play an important role in androgen formation and action in peripheral tissues.

Effect of some alkaloids, flavonoids and triterpenoids, contents of Japanese-Chinese traditional herbal medicines, on the lipogenesis of sebaceous glands.

The effects of some alkaloids and flavonoids, which are major ingredients in some of the Japanese Kampoh drugs (Japanese-Chinese traditional herbal medicines) experientially known to be efficacious for the treatment of acne vulgaris, on the lipogenesis in the sebaceous glands of the hamster ear, an excellent animal model for the human sebaceous gland, were studied. Lipogenesis was assayed by determining 14C incorporation into sebaceous lipids extracted from the sebaceous glands which were preincubated with 14C-acetate. We found that the lipogenesis in the hamster sebaceous glands was suppressed 63 and 54% by 10(-4) M berberine (an alkaloid) and wogonin (a flavonoid), respectively. We suggest that the therapeutic effects of some Japanese Kampoh drugs experimentally used for acne vulgaris could be due to inhibition of lipogenesis by their active ingredients such as berberine and wogonin.

Organ maintenance of human sebaceous glands: in vitro effects of 13-cis retinoic acid and testosterone.

Human sebaceous glands were isolated by shearing, and maintained for 7 days either on defined medium, on medium supplemented with 3 microM-testosterone or on medium supplemented with both 3 microM-testosterone and 1 microM-13-cis retinoic acid. Freshly isolated glands retained their in vivo morphology. On maintenance, the glands retained their freshly isolated rates of cell division, but the sebocytes showed increased keratinization and there was multilayering of the peripheral undifferentiated cells. However, glands maintained in the presence of 1 microM-13-cis retinoic acid showed very little luminal keratinization and only a small degree of multilayering. On autoradiography, freshly isolated glands retained their in vivo pattern of [methyl-3H]thymidine incorporation. Similar patterns were seen when glands were maintained for 7 days with or without testosterone. However, in the presence of both testosterone and 13-cis retinoic acid there was only slight graining. Following 7 days maintenance the rate of lipogenesis fell significantly. This was partially reversed by testosterone, but further inhibited by 13-cis retinoic acid. The patterns of lipids that are synthesised after a week's maintenance are very similar to those seen in freshly isolated glands, except that the squalene:cholesterol ratio is reversibly regulated by 3 microM-testosterone and 1 microM-retinoic acid. Protein synthesis was maintained at the same rates as for freshly isolated glands under all conditions of maintenance. Whereas DNA synthetic rates were maintained in the presence of testosterone, they were significantly inhibited by 13-cis retinoic acid. Glandular wet weights were retained under all conditions of maintenance, except that they were significantly reduced by 13-cis retinoic acid. This study shows that human sebocytes continue to divide on organ maintenance, but that they do not differentiate fully. However, this provides the first demonstration that 13-cis retinoic acid acts on human sebaceous glands directly, reducing the rate of cell division and the rate of lipogenesis, which shows that the maintained human sebaceous gland might provide a useful model for studying the effect of 13-cis retinoic acid on human sebocytes.

Estradiol distribution and penetration in rat skin after topical application, studied by high resolution autoradiography.

Transdermal pathways and targets in the skin for estradiol were investigated using dry-mount autoradiography. 3H-estradiol-17 beta was applied at doses of 30.1 pmol, 120.4 pmol and 301 pmol/cm2 to shaved rat skin in the dorsal neck region. Vehicles were DMSO, ethylene glycol or sesame oil. After 2 h of topical treatment with 30.1 pmol 3H-estradiol x cm-2 dissolved in DMSO a distinct cellular distribution was apparent. Target cells with concentrations of radioactivity were found in epidermis, sebaceous glands, dermal papillae of hair and fibroblasts. After treatment with 120.4 and 301 pmol/cm2, a penetration gradient of radioactivity was recognizable however it masked specific cellular and subcellular uptake. The stratum corneum accumulated and retained radioactivity, apparently forming a depot for the hormone. Strong concentration and retention of the hormone was conspicuous in sebaceous glands for more than 24 h, suggesting that sebaceous glands serve as a second storage site for the hormone. In all autoradiograms two penetration pathways to the dermis were visible: one through the stratum corneum and epidermis, the other through the hair canals and hair sheaths.