Mouse Skin Collagen Research Articles

The Effect of Giving Aloe Vera Gel on Collagen Growth in Wistar Rats (Rattus Norvegicus) with Exposure to Ultra Violet-B Light

Exposure to UV rays can cause photochemical damage to the DNA of cells in the body, triggering cancer formation, especially skin cancer in humans. The skin may lose elasticity. Research is needed to ensure that currently, we are still looking for plants or foods that contain collagen, which can prevent wrinkles. This research is an original experiment carried out in a laboratory. Two types of variables play a role in this research: independent variables and dependent variables. In this experiment, aloe vera gel was used as an independent variable as a substitute for UVB light exposure. Collagen development, measured in mouse skin, is the dependent variable here. This study found that the standard control group had no collagen growth and was stable. This was because the typical control treatment was not exposed to UVB rays; hence, collagen formation was stable. The group administered 15% aloe vera extract gel had a more substantial effect on rat skin tissue collagen development after UVB light exposure than the 5% and 10% groups. This is because a higher dose of aloe vera extract includes more chemical components that promote mouse skin collagen formation.

Diameter distributions of collagenous tissues in relation to sex. A quantitative ultrastructural study

A number of factors have been implicated in the regulation of collagen fibril diameter. Electron microscopy analysis was used to investigate the role of sex on fibril diameter. Female mouse skin collagen fibrils’ mean diameter values were significantly smaller than those from the male, independent of age. In addition, the female rabbit collagen fibrils had a marked decrease in the mean diameter compared to male, in all the tissues examined (skin, liver, and bone). These data suggest that the collagen fibril diameter is related to sex.

Influence of low doses of gamma-irradiation on mouse skin collagen fibrils

The structure of mouse skin collagen fibrils after treatment with 0. 5, 1 and 2.5 Gy gamma-irradiation was studied by electron microscopy. Animals were sacrificed 1, 4 and 8 weeks after irradiation. Although there were areas where the normal parallel packing of fibrils was retained in some regions packing was interrupted by abnormal fibrils and in some cases helical twisting was apparent. Irradiated collagen fibrils had a lower mean diameter compared with normal and a large variability in width. The diameter of 0. 5 Gy irradiated fibrils returned to normal by 4 or 8 weeks after irradiation. Clusters of abnormal fibrils were found when viewed in crosssections. Their number and size was reversibly dependent on the dose level. All fibrils retained normal banding periodicity. Computer analysis of irradiated and control patterns led to the conclusion that 0. 5-2.5 Gy gamma-irradiation had no considerable effect in modifying the charge distribution along the mouse skin collagen fibril.

An electron microscopic study of collagen fibril structure after lithium treatment—II. The effects of low lithium dose and short treatment on mouse skin collagen

The structure of mouse skin collagen fibrils, after treatment with lithium chloride at a dose of 0.7 meq/kg of body weight, was studied by electron microscopy. Animals were sacrificed 1-day, 1-, 2- and 6-months after the end of 30 consecutive days experimental period. Fibrils in disarray interspersed with normal ones were seen, although there were areas where the normal parallel packing of fibrils was completely replaced by a random arrangement. In some regions this packing was interrupted by fibrils forming a ‘hairpin loop’ and in some others helical twisting was apparent. Lithium treated collagen fibrils had a marked decrease in mean diameter compared to normal with a high variability in width. Clusters of abnormal fibrils were found when viewed in cross-sections, constituted approximately 10% of the whole population with an irregular outline. A shorter experimental period (7 days) leads to the same features in collagen disorganization as with the longer experimental period (30 periods). However, in short lithium treatment, there is no high variability in fibril width and although fibrils are smaller than the control, the decrease in mean diameter is not so pronounced as with longer treatment. In general, fibril diameter becomes altered progressively with experimental time. Lower dose, 0.3 meq Li/kg, in short treatment (7 days), leads to a normal collagen organization although in some areas fibril twisting is observed. Fibril diameter is not considerably affected.

UVA- and UVB-induced changes in hairless mouse skin collagen.

UVA- and UVB-induced alterations in dermal collagen were investigated in a murine animal model. Groups of hairless mice were exposed to UVA and UVB for 28 weeks at a dose of 60 J/cm2 three times weekly and 0.06 J/cm2 three times weekly, respectively. Untreated animals were used as controls. Every 4 weeks dorsal skin was examined for quantitative and qualitative changes in dermal collagen. Neither UVA nor UVB caused a significant alteration in total skin collagen content. However, after UVA treatment the ability of skin collagen to be digested by pepsin decreased dramatically (up to 65% of skin collagen remained insoluble after 4 months), whereas exposure to UVB had no significant effect. Furthermore a shift in the ratio of alpha 1(I,III) chains to alpha 2(I) chains was detected after UVA exposure. The amount of type V collagen in mouse skin, as determined by a sensitive ELISA method, was markedly decreased after UVA treatment, but not after UVB treatment.

An electron microscopic study of collagen fibril structure after lithium treatment—I. The effect of different lithium doses on mouse skin collagen

The structure of mouse skin collagen fibrils after treatment with lithium chloride at doses of 1.5 and 6 meq/kg of body weight was studied by electron microscopy. Animals were sacrificed 1 day, 1, 2 and 6 months after the end of a 30 consecutive days experimental period. With the first dose, which is commonly used clinically, although there were areas with normal collagen fibrils there were also regions where the characteristic parallel packing of fibrils was lost completely or it was preserved for a part of the area. With high doses, in most regions the normal packing of fibrils was replaced by an anarchic arrangement. In both cases, collagen fibrils had a marked decrease in mean diameter and showed a higher degree of variability in width and shape than collagen fibrils from controls. Also, many clusters of abnormal fibrils were found with a diameter of up to 260 nm vs 109 nm and a highly irregular outline when viewed in cross-sections. The periodicity D as well as the banding pattern were normal.

The effect of gamma irradiation on collagen fibril structure

The structure of mouse skin collagen fibrils treated with 500 rad gamma irradiation was studied by electron microscopy. Examination of specimens after 1, 4 and 8 weeks of treatment revealed collagen fibrils consistently larger in diameter than those from normal specimens with the majority of irradiated fibrils measuring 110–138 nm, as opposed to 62–84 nm in the control. No marked differences in cross-linking were detected between irradiated and control reconstituted type I or type III collagen, either by polyacrylamide gel electrophoresis or by thermal stability measurements.

The effect of gamma irradiation on the organization of mouse skin collagen fibrils. The positive staining pattern

The organization as well as the positive staining pattern of mouse skin collagen fibrils treated with 500 rad gamma irradiation were studied by electron microscopy. The parallel packing of fibrils remained throughout without any areas of disorganization, also all fibrils were seen to retain normal banding periodicity. These observations suggest that gamma irradiation leads to aggregation of collagen into a regular arrangement of fibrils, as well as to normal axial relationships between the molecules within a fibril.

Tumor-promoting phorbol esters cause a stable reduction of dermal collagen in mouse skin

Chronic treatment with the tumor-promoting phorbol esters 12- O-tetradecanoylphorbol-13-acetate (TPA) and 12- O-retinoylphorbol-13-acetate (RPA) causes permanently increased levels of active collagenolytic enzymes in the dermis and leads to a stable reduction of dermal collagen content. Non-promoting skin mitogens like the Ca-ionophore A 23187 or the 4- O-methylether of TPA, while being active stimulators of collagenolytic enzymes, do not support chronic collagen degradation throughout the experimental period. On the other hand, TPA-induced collagen degradation is not necessarily influenced by inhibition of tumor promotion. Fluocinolone acetonid (FA), an inhibitor preventing not only tumor development but also chronic inflammation and the establishment of a stationary hyperplasia, has been compared with retinoic acid (RA) which has no influence on either the inflammatory reaction or hyperplasia. While FA inhibited the dermal effects of TPA almost completely, RA at a dose that prevented tumor development by 80% had no effect whatsoever in this respect. Therefore, we conclude that both epidermal proliferation and inflammation are accompanied by collagenolytic reactions in the dermis. During chronic treatment sustained collagenolysis correlates with inflammation and/or the establishment of a stationary hyperplasia. Like these it can be regarded as a necessary but insufficient condition of tumor promotion (second stage).

Changes in collagen with age—V. Modification of mouse skin collagen by whole body X-irradiation

Male mice (SM/J), age 26–33 weeks, were exposed to 0·6 krads of whole body X-irradiation and sacrificed 36 weeks later. The skins were removed and the neutral salt soluble (NSC), acid soluble (ASC), and insoluble (ISC) collagen fractions were isolated. The results obtained on examination of these three fractions suggest that exposure to X-irradiation results in an increased lability of the insoluble collagen matrix and a deposition of non-collagenous proteins.

Changes in collagen with age—III. The isolation and partial characterization of the pre-α fragment

The so-called “pre-α” fragment, which is obtained on CM-cellulose chromatographic separation of collagen, has frequently been studied to assess its possible role in collagen aging. The present study concerns pre-α fragments which have been isolated from calf skin collagen, bovine achilles tendon and from mouse skin collagen. These pre-α fragments were partially characterised and the conditions leading to their formation were investigated. The results indicate that the pre-α fragments appear to be only of peripheral interest from the point of view of aging studies, since the amounts of pre-α obtained appear to be mainly a consequence of the experimental conditions employed and, therefore, may not reflect age-related changes in collagen.

Action of ultra-violet light on soluble collagens.

IT has been shown1 that rat tail tendon becomes less soluble after exposure to short wave ultra-violet light and that the amount of soluble collagen in mouse skin was decreased after irradiation2. Fujimori3, working with acetic acid solutions of calf skin collagen, recently showed that irradiation resulted in the acquirement of ability to fluoresce in long wave ultra-violet light. These changes in properties have been ascribed to the formation of cross-links from the aromatic side-chains of phenyl-alanine and tyrosine3,4. Working with suspensions of acid-soluble and neutral salt-soluble collagens from rat skin we have also found that short wave ultra-violet light does produce fluorescence, and we have sought to measure the fluorescence quantitatively and correlate this with changes of solubility and shrinkage temperature after different periods of irradiation.