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Extradermal melanin transfer? Lack of macroscopic spleen melanization in old C57BL/6 mice with de-synchronized hair cycle

100%

Michalczyk D., Popik M., Salwinski A., Plonka P. M.

issue 2

343-354

In quest of alternate, extradermal path of melanin transfer from skin to the visceral organs, we suggested that some portions of such melanin may be deposited in the spleen, which in young black C57BL/6 mice is often melanized. Here, we confirm these observation using young C57BL/6 female mice (up to 17 weeks) and show that this phenomenon cannot be observed in old animals where the hair cycle is not synchronized any more. The experiments were carried out both on spontaneous and depilation-induced hair cycle. We have checked it as a side-observation over many other experiments carried out on young and old C57BL/6 female mice (up to 2.5 years of life). The presence or absence of melanin in the spleens was checked macroscopically, and histologically by Fontana-Masson (FM) staining, and synchronization of the hair cycle - by standard histomorphometric analysis of the back skin hair follicles. In about 40% of old spleens black FM-stainable 'debris' could be found under closer histological examination. This study shows that, at least in part, the phenomenon of splenic melanosis in C57BL/6 mice can be correlated with the synchronized skin melanization parallel to the hair cycle progress, and that splenic melanin undergoes gradual degradation during the mouse life.

Splenic eumelanin differs from hair eumelanin in C57BL/6 mice.

76%

Plonka P. M., Michalczyk D., Popik M., Handjiski B., Slominski A., Paus R.

2005

vol. 52

issue 2

433-441

The presence of melanin in spleens of black C57BL/6 mice has been known for long. Although its origin and biological functions are still obscure, the relation of splenic melanin to the hair follicle and skin pigmentation was suggested. Here, we demonstrated using for the first time electron paramagnetic resonance spectroscopy that black-spotted C57BL/6 spleens contain eumelanin. Its presence here is a "yes or no" phenomenon, as even in the groups which revealed the highest percentage of spots single organs completely devoid of the pigment were found. Percentage of the spotted spleens decreased, however, with the progress of telogen after spontaneously-induced hair growth. The paramagnetic properties of the spleen eumelanin differed from the hair shaft or anagen VI skin melanin. The splenic melanin revealed narrower signal, and its microwave power saturability betrayed more heterogenous population of paramagnetic centres than in the skin or hair shaft pigment. Interestingly, the pigment of dry hair shafts and of the wet tissue of depilated anagen VI skin revealed almost identical properties. The properties of splenic melanin better resembled the synthetic dopa melanin (water suspension, and to a lesser degree - powder sample) than the skin/hair melanin. All these findings may indicate a limited degradation of splenic melanin as compared to the skin/hair pigment. The splenic eumelanin may at least in part originate from the skin melanin phagocyted in catagen by the Langerhans cells or macrophages and transported to the organ.

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2 Acta Biochimica Polonica

1 2009

1 2005

2 Michalczyk D.

2 Plonka P. M.

2 Popik M.

1 Handjiski B.

1 Paus R.

1 Salwinski A.

1 Slominski A.

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Extradermal melanin transfer? Lack of macroscopic spleen melanization in old C57BL/6 mice with de-synchronized hair cycle

Splenic eumelanin differs from hair eumelanin in C57BL/6 mice.