Heavy metals in green mussels (Perna viridis) from the Gulf of Thailand.

Concentrations of seven heavy metals were determined in green mussels (Perna viridis) collected between April and June 1995 from eight locations along the costal area of the Gulf of Thailand. The average concentrations (n = 96) of the heavy metals detected in mussel samples, on the basis of dry weight, were 1.20 mg kg-1 cadmium, 0.78 mg kg-1 for chromium, 9.85 mg kg-1 for copper, 1.09 mg kg-1 for lead 2.78 mg kg-1 for manganese, 1.54 mg kg-1 for nickel, and 94,48 mg kg-1 for zinc. The levels of cadmium, chromium, nickel, and lead found in green mussels from four locations in the Upper Gulf were significantly (P < 0.05) higher than those detected in mussels from four locations in the Lower Gulf, while the levels of copper, manganese, and zinc did not differ significantly (P > 0.05) between the Upper and Lower Gulf. Comparison with earlier studies revealed that the concentrations of some metals in the mussels collected from the Upper Gulf are increasing. The concentrations of heavy metals in green mussels from the Gulf of Thailand were within acceptable levels for human consumption.

Human chorionic gonadotropin treatment prevents depressed 17 alpha-hydroxylase/C17-20 lyase activities and serum testosterone concentrations in 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated rats.

It is known that administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes decreased serum testosterone concentrations in the rat. Previous studies in this laboratory have shown that in rats TCDD exposure results in decreased 17 alpha-hydroxylase and C17-20 lyase activities. The decreases in these activities paralleled decreases in testicular microsomal heme and cytochrome P450 contents. As reported herein, neither testicular mitochondrial cytochrome P450 content nor the activity of cholesterol side-chain cleavage was altered in rats exposed to TCDD. Since the production of testosterone in the testis is dependent on LH, it is important to determine the early effects of TCDD on serum LH concentrations in the rat. Male Sprague-Dawley rats were given a single, oral dose of TCDD (50 micrograms/kg). Serum LH concentrations were determined by RIA on Days 1, 2, 3, 5, and 7 following TCDD treatment. Rat serum LH concentrations were decreased to 60% of controls as early as Day 1 and continued to be depressed on Days 2 and 3 at 53% and 59% of control values, respectively. Rat serum LH returned to control values by Day 5 in spite of continued depression of serum testosterone concentrations. The early depression in serum LH levels caused by TCDD may be related to the subsequent androgenic deficiency in the rat. Treatment of rats with hCG was found to be able to prevent the depression of the activities of testicular microsomal 17 alpha-hydroxylase and C17-20 lyase and serum testosterone concentrations caused by TCDD. These data indicate that TCDD decreases serum testosterone by decreasing P450(17 alpha) and C17-20 but not P450sec activities and that hCG treatment prevents the TCDD-induced decrease.