• Molecular & Cellular Toxicology
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• v.4 no.3
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• pp.230-234
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• 2008

Epidemiological studies demonstrate an adverse effect of several environmental and occupational exposures on male sex hormone. Bisphenol A (BPA) is a weak estrogen and a widely used industrial chemical. Epoxy resin painters may be continuously exposed to BPA at high concentrations. The effect of occupational exposure of BPA on male reproduction was examined by measuring the urinary BPA, testosterone and gonadotropic hormones of epoxy resin painters in the shipyard. The painters had significantly higher concentrations of urinary BPA (2.61${\pm}$1.08 ${\mu}g$/g creatinine) than controls (1.38${\pm}$0.5 9 ${\mu}g$/g creatinine). In serum, the testosterone level of painters was significantly decreased but the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels of painters were significantly higher than controls. Occupational exposure to BPA influences testosterone and gonadotropic hormones in male workers.

• Journal of Marine Life Science
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• v.8 no.1
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• pp.32-42
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• 2023

Fish reproduction is regulated by various neurohormones secreted from the brain and gonadotropic hormones secreted from the pituitary. Reproduction of eel (Anguilla japonica) is also regulated by these hormones. However, how the neurohormones regulate the secretion of pituitary hormones during sexual maturation is not completely understood. Previous studies have shown that neurohormones such as progesterone (P4), melatonin and serotonin (5-HT) are involved in the regulation of reproductive processes in some fish. In this study, the eel pituitary was primary cultured, and stabilized pituitary cells were treated with P4, 17β-estradiol (E2), melatonin, or 5-HT. The effect of these treatments on the expression of FSHβ, LHβ, GH and SL mRNA was, then, investigated. P4 increased the expression of FSHβ and LHβ in pituitary cells, and melatonin increased the expression of GH and SL as well as FSHβ and LHβ. However, 5-HT did not significantly affect the expression of these mRNA. These results suggest that P4 and melatonin may play some important roles in the early sexual maturation of eels.

• Applied Microscopy
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• v.31 no.1
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• pp.19-35
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• 2001

Outlines for plasma $estradiol-17\beta$, components, electrophoretic patterns, and ultrastructural changes were obtained in female rainbow trout (Oncorhynchus mykiss) during the seasonal reproductive cycles. Plasma $estradiol-17\beta$ under the natural conditions, exhibited distinct seasonal variation, peaking very late in vitellogenic season during September, decreasing gradually the halt of spawning in December, and ultimately falling during the early stages of seasonal ovarian recrudescence in February and March. This change in $estradiol-17\beta$ appeared to stimulate vitellogenin production as evidenced by increases in plasma calcium, phosphorus, glucose, albumin and total protein levels. The electrophoretic patterns of late maturing or spawning oocytes were stained more intensively than those of late perinucleolus oocytes (molecular weights of approximately 70,000 and 200,000). Two protein bands were found in the SDS-PAGE separation, coincident with the $estradiol-17\beta$ hormone peak. Gonadosomatic indices (GSI) significantly increased from October to January, and showed the highest peak in January, coinciding with the numerically abrupt increase of ripe ova in female. A positive correlation (r=0.701, p<0.01) was established between plasma $estradiol-17\beta$ levels and the gonadosomatic index during the prespawning. The highest level of hepatosomatic index (HSI) observed in December. During the breeding season (December), the gonadotropes were large and filled with GTH-containing inclusions such as granules and globules. The vitellogenic phase began as late perinurleolus oocytes became transformed into early maturing oocytes through the accumulation of yolk, and oocytes reached the late maturing stages as the ooplasm was completely packed with yolk. Marked ultrastructural changed in the granulosa cells during nuclear migration involve the dilation of the rough endoplasmic reticulum and the appearance of the rod-shaped mitochondria with tubular cristae. Microvilli (finger-like projections), from the zona radiata and from the oocyte grew, and made contact with each other in the pore canals of the zona radials during vitellogenesis, but were withdrawn as the zona radiata became more compact and devoid of pore canals during oocyte maturation. The zona radiata grew to a tripartite structure such as an outer thin homogeneous layer, and two inner thick helicoidal layers (zona radials interna and zona radiata externa). Under the normal conditions, the ovarian follicle influenced the histological development and periodical secretion of the hormones , sufficient for a oogenesis and gonadal steroid production.