The characteristics of aromatase deficient hairless mice indicate important roles of extragonadal estrogen in the skin

Skin aging modulates percutaneous drug absorption: the impact of ultraviolet irradiation and ovariectomy

Ultraviolet (UV) exposure and menopause are known as the inducers of damage to the skin structure. The combination of these two factors accelerates the skin aging process. In this study, we aimed to evaluate the influence of UV and ovariectomy (OVX) on the permeation of drugs through the skin. The role of tight junctions (TJs) and adherens junctions (AJs) in the cutaneous absorption of extremely lipophilic permeants and macromolecules was explored. The OVX nude mouse underwent bilateral ovary removal. Both UVA and UVB were employed to irradiate the skin. The physiological and biochemical changes of the skin structure were examined with focus on transepidermal water loss (TEWL), skin color, immunohistochemistry, and mRNA levels of proteins. UVB and OVX increased TEWL, resulting in stratum corneum (SC) integrity disruption and dehydration. A hyperproliferative epidermis was produced by UVB. UVA caused a pale skin color tone due to keratinocyte apoptosis in the epidermis. E-cadherin and β-catenin showed a significant loss by both UVA and UVB. OVX downregulated the expression of filaggrin and involucrin. A further reduction was observed when UV and OVX were combined. The in vitro cutaneous absorption demonstrated that UV increased the skin permeation of tretinoin by about twofold. However, skin accumulation and flux of estradiol were not modified by photoaging. OVX basically revealed a negligible effect on altering the permeation of small permeants. OVX increased tretinoin uptake by the appendages from 1.36 to 3.52 μg/cm(2). A synergistic effect on tretinoin follicular uptake enhancement was observed for combined UV and OVX. However, the intervention of OVX to photoaged skin resulted in less macromolecule (dextran, molecular weight = 4 kDa) accumulation in the skin reservoir because of retarded partitioning into dry skin. The in vivo percutaneous absorption of lipophilic dye examined by confocal microscopy had indicated that the SC was still important to controlling topical delivery, although the role of epidermal junctions could not be simply ignored.

Estrogen receptor-mediated signalling in female mice is locally activated in response to wounding

Estrogen deprivation is associated with delayed healing, while Hormone Replacement Therapy (HRT) accelerates acute wound healing and protects against development of chronic wounds. Estrogen exerts its effects on healing via numerous cell types by signalling through the receptors ERα and ERβ, which bind to the Estrogen Responsive Element (ERE) and initiate gene transcription. The ERE-luciferase transgenic mouse model has been influential in assessing real-time in vivo estrogen receptor activation across a range of tissues and pathologies. Using this model we demonstrate novel temporally regulated peri-wound activation of estrogen signalling in female mice. Using histological methods we reveal that this signal is specifically localised to keratinocytes of the neoepidermis and wound margin dermal cells. Moreover using pharmacological agonists we reveal that ERβ induces ERE-mediated signal in both epidermal and dermal cells while ERα induces ERE-mediated signal in dermal cells alone. Collectively these novel data demonstrate rapid and regional activation of estrogen signalling in wounded skin. A more complete understanding of local hormonal signalling during repair is essential for the focussed development of new therapies for wound healing.

Gender-dependent differences in degree of facial wrinkles

BACKGROUND/PURPOSE

This study aimed to reveal gender-dependent differences in the degree of facial wrinkles.

METHODS

Subjects comprised 173 Japanese men and women, divided into four groups according to age. Photographs were taken from nine facial regions and used to classify the intensity of wrinkles into five grades. In addition, replicas were taken from five facial sites and used to measure surface roughness. Data were compared between men and women within each age group.

RESULTS

In all age groups, men showed increased forehead wrinkles compared with women. In contrast, no gender-dependent differences were found in upper eyelid wrinkles. Other facial wrinkles were greater in men than in women in all except the oldest group (age, 65-75 years), in which wrinkles in women were greater than or equal to those in men.

CONCLUSION

Our results showed that gender-dependent differences exist in the degree of facial wrinkles. In general, men tend to have more severe wrinkles than women. This tendency disappeared or was reversed in some regions of the face and in individuals more than 60 years old.