Neurochemical Effects of Consumption of Great Lakes Salmon by Rats

Polychlorinated biphenyls and methylmercury act synergistically to reduce rat brain dopamine content in vitro.

“…The magnitude of the decrease in punch DA content after combined exposure to MeHg and PCBs (a 20-50% decrease depending on the level of the contaminants studied) is not as great as that seen in rat brain after developmental exposure to the complex mixture of contaminants found in Great Lakes salmon (10). Although there are methodologic differences between these studies (e.g., in vivo vs. in vitro), we suggest that a major difference is related to the greater number of putative neurotoxicants present in the contaminated fish as compared to the two neurotoxicants studied here.…”

“…Effect of (A) 4 Figure 3. Effect of (A) 4 pM methylmercury, (B) 10 pM MeHg, or (C) 14 Arcor 545 0M (ppm) Figure 4. Effect of (A) 4 Figure 2C) with exposure to 14 pM MeHg only; 14 p1M MeHg combined with 40, 100, and 200 ppm PCB was significantly different from exposure to PCBs only at the p < 0.1 to p < 0.01 level, which resulted in a MeHg x PCB statistical interaction (F = 9.39; df= 5, 18; p < 0.001).…”

“…DOPAC concentrations were elevated in tissue exposed to 14 pM + 40 ppm PCBs only (p < 0.1) ( Figure 3C) and media from tissue exposed to 14 pM MeHg combined with 200 ppm PCB (p < 0.05) ( Figure 4C (10,11,23), most likely due to the inhibition of tyrosine hydroxylase (TH), the rate-limiting enzyme in DA synthesis. Inhibition of TH by PCBs has been demonstrated in striatal slices exposed to NSD-1015, which inhibits aromatic amino acid decarboxylase (AADC).…”

“…For this initial study we used striatal tissue punches, rather than cells in culture, because the explanted tissue conserves much of the neuronal complexity and many of the neurotransmitter interactions of the intact brain. We examined changes in DA function because developmental exposure of laboratory rodents to lyophilized Great Lakes fish containing the above contaminants results in significant decreases in regional brain concentrations of DA (10).…”

Electrophysiologic and behavioral effects of perinatal and acute exposure of rats to lead and polychlorinated biphenyls.

“…However, Zahalka et al (63) were not able to replicate these observations in a different strain of rats. Seegal et al (62) measured dopamine levels in the frontal cortex, nucleus accumbens, caudate nucleus, hippocampus, and substantia nigra of rats fed diets supplemented with contaminated (either 5 or 20% w/w) lyophilized fillets of salmon from Lake Huron or Lake Ontario. Significant reductions in dopamine were found in the frontal cortex and caudate nucleus.…”