Orally administered sphingomyelin in bovine milk is incorporated into skin sphingolipids and is involved in the water-holding capacity of hairless mice.
BACKGROUND
We previously reported that dietary sphingomyelin (SM) concentrate from bovine milk improves epidermal functions. SM is a known precursor of ceramide (Cer) in the stratum corneum (SC). Neither the uptake nor distribution of orally administered SM nor its effects on epidermal functions have been demonstrated.


OBJECTIVE
We evaluated the effects of dietary SM on epidermal functions, and the distribution and fate of its radiolabeled metabolites in mice orally administered [4,5-(3)H-sphinganyl] sphingomyelin ((3)H-SM).


METHODS
Bovine milk SM (98% purity) was administered orally to 13-week-old hairless mice at 142 mg/kg per day for eight weeks. Their SC hydration, transepidermal water loss (TEWL), and SC Cer content were measured. (3)H-SM was then administered orally to 10-week-old hairless mice. Its distribution and metabolites in the skin were evaluated with whole-body autoradiography, liquid scintillation counting, and thin-layer chromatography.


RESULTS
SC hydration in the SM-administered mice was higher than that in control mice, whereas their TEWL and Cer contents did not differ. Radioactivity was distributed extensively in the bodies of the experimental mice and decreased gradually with time. In contrast, the radioactivity in the SC remained constant after its administration, and radiolabeled SM and Cer were detected in the skin. This suggests that dietary SM is transferred to the skin and then converted to Cer in the SC.


CONCLUSIONS
Orally administered SM is incorporated into skin SM and converted to SC Cer, which is involved in the water-holding capacity of the SC.
Milk Science Research Institute, Megmilk Snow Brand Co., Ltd, 1-1-2 Minamidai, Kawagoe, Saitama 350-1165, Japan.
Yuko
Y
Haruta-Ono
Shuichi
S
Setoguchi
Hiroshi M
HM
Ueno
Satoshi
S
Higurashi
Noriko
N
Ueda
Ken
K
Kato
Tadao
T
Saito
Kazuhisa
K
Matsunaga
Jiro
J
Takata
D000284:Administration, Oral; D000818:Animals; D001345:Autoradiography; D001711:Biotransformation; D001834:Body Water / Q000378:metabolism*; D002518:Ceramides / Q000378:metabolism; D002855:Chromatography, Thin Layer; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D008892:Milk / Q000737:chemistry*; D012867:Skin / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism*; D013109:Sphingomyelins / Q000008:administration & dosage* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D014316:Tritium; D014870:Water Loss, Insensible; D051598:Whole Body Imaging
D002518:Ceramides; D013107:Sphingolipids; D013109:Sphingomyelins; D014316:Tritium