Royal jelly increases collagen production in rat skin after ovariectomy

Abstract

Royal jelly (RJ) is a honeybee product that contains proteins, carbohydrates, fats, free amino acids, vitamins, and minerals. RJ has been reported to have antitumor, antibacterial, and wound-healing activities. We previously reported that RJ enhanced the migration of human dermal fibroblasts and altered the levels of cholesterol and sphinganine in an in vitro wound-healing model in addition to regulating skin photoaging following exposure to ultraviolet-B radiation. We established an animal model of skin aging in the context of estrogen deficiency and assessed the antiaging effects of RJ on skin. To establish an in vivo model of skin aging, bilateral ovariectomies were performed in 12-week-old virgin female Sprague-Dawley rats. Induction of osteoporosis was confirmed through two-dimensional images of the trabecular bone in the left femoral necks using microcomputed tomography. The protective effects of RJ ovariectomy-induced skin aging were examined by determining the protein expression of type I procollagen and matrix metalloproteinase (MMP)-1. The collagen content and epidermal thickness of skin tissue were measured by staining techniques. There was a significant difference in weight between sham-operated and ovariectomized groups. Food efficiency ratio did not differ significantly among the groups. The level of procollagen type I protein was increased in the dorsal skin of ovariectomized rats fed with a dietary supplement containing 1% RJ extract, but the level of MMP-1 was not altered. In particular, the amount of collagen recovered was close to the normal level. RJ may protect against skin aging by enhancing collagen production in rats with ovariectomy-induced estrogen deficiency.

FIG. 1.

Experimental design.

FIG. 2.

High-performance liquid chromatography chromatograms of (E)-10-hydroxy-2-decenoic acid (10H2DA) of royal jelly from Cheorwon (A) and from Pocheon (B).

FIG. 3.

Two-dimensional images of trabecular bone in the femoral necks of the SHAM (A) and OVX (B) groups using microcomputed tomography parameters.

FIG. 4.

Alkaline phosphatase (ALP) activities (A) and osteocalcin levels (B) in sham-operated rats that were fed a control diet only (SHAM) and ovariectomized rats that were fed a control diet (OVX), a diet including royal jelly from Pocheon (OP), and a diet including royal jelly from Cheorwon (OC) for 12 weeks. All values are mean±SEM (n=12 for SHAM, OP, and OC; n=11 for OVX). The data were evaluated for statistical significance with one-way ANOVA followed by Duncan's multiple range test. ^abcMeans with different letters are statistically different.

FIG. 5.

(A, C, E, G) The histological appearance and (B, D, F, H) Masson's trichrome staining of (A, B) sham-operated rats that were fed a control diet only (SHAM), and (C, D) ovariectomized rats that were fed a control diet (OVX) and diets including royal jelly from (E, F) Pocheon (OP) and (G, H) Cheorwon (OC) for 12 weeks. Color images available online at www.liebertonline.com/jmf

FIG. 5.

(A, C, E, G) The histological appearance and (B, D, F, H) Masson's trichrome staining of (A, B) sham-operated rats that were fed a control diet only (SHAM), and (C, D) ovariectomized rats that were fed a control diet (OVX) and diets including royal jelly from (E, F) Pocheon (OP) and (G, H) Cheorwon (OC) for 12 weeks. Color images available online at www.liebertonline.com/jmf

FIG. 6.

Expression of procollagen type I and matrix metalloproteinase (MMP)-1 proteins in rats fed a control diet only (SHAM) and ovariectomized rats fed a control diet (OVX), and diets including royal jelly from Pocheon (OP) and Cheorwon (OC) for 12 weeks.