Abstract
Continuous industrial productivity and modern societies have resulted in excess artificial light. The altered circadian rhythm causes many diseases. During intrauterine life, the mother's maternal melatonin rhythm has a major role in influencing organ development. The aim of this study was to investigate the effect of maternal exposure to constant light on the structure and ultrastructure of neonatal skin. Twenty pregnant New Zealand rabbits were divided into two groups (n=10 each): control group (12-h light/dark) and constant light group (24-h light). Plasma maternal melatonin and corticosterone during pregnancy were determined. At the end of the experiment, the dorsal skin of the neonates of both groups was collected and prepared for histological, morphometric, and transmission electron microscopic study. Histological and morphometric results of skin of neonates from the constant light group revealed statistically significantly reduced epidermal thickness, decreased number of hair follicle, increased surface area of collagen, and decreased proliferating cell nuclear antigen (PCNA) positive cells. Ultrastructural examination showed wide intercellular spaces and disrupted desmosomal junctions in the epidermis. Earlier stages of hair follicles were also observed with indented shrunken nuclei, vacuolization, and swollen mitochondria. Dermal fibroblasts with dilated cisternae of rough endoplasmic reticulum containing electron-dense material were detected. Maternal melatonin was significantly reduced in the constant light group while maternal corticosterone showed no significant difference between groups. Therefore, normal maternal circadian rhythm is a key factor for the integrity of neonatal skin structure.
Highlights
The skin is the largest organ of the body; it occupies about one-sixth of total adult body weight
Serological results The mean maternal nocturnal serum melatonin progressively increased throughout the gestation with the maximum value on the 30th gestational day in the control group, while the serum melatonin levels were nearly constant throughout the gestation in the constant light group
The maternal melatonin levels of the constant light group reduced significantly (Po0.05) on the 16th gestational day and more significantly (Po0.001) on the 24th and 30th gestational days compared to the control group (Figure 1A)
Summary
The skin is the largest organ of the body; it occupies about one-sixth of total adult body weight. It has many vital functions, such as regulation of body temperature, protection against external physical, chemical, and biological stimuli, and prevention of excess water loss from the body [1]. The hair follicle is a characteristic feature of humans and other mammals. Hair in humans serves many functions such as protection against external stimuli. Hair follicles and sebaceous glands are developed from neuroectodermal and mesodermal origin. They are strongly correlated to the neuroendocrine system and affected by its hormones, e.g., prolactin, melatonin, corticosterone, and thyroid hormones [3]
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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