Vitamin E co-treatment reduces Aroclor 1254-induced impairment of reproductive neuroendocrine function in Atlantic croaker

Aroclor 1254 inhibits tryptophan hydroxylase activity in rat brain

“…However, the mechanism by which Aroclor 1254 causes the decrease in TPH activity has not been investigated in rats. In a recent study with Atlantic croaker, we observed a decrease in TPH protein after Aroclor 1254 exposure, which was accompanied by an increased formation of malondialdehyde-protein adducts (Khan and Thomas 2004). These results suggest that one of the mechanisms of Aroclor 1254 neurotoxicity may involve oxidative damage to TPH protein resulting in reduced TPH activity and 5-HT concentrations.…”

Non-coplanar polychlorinated biphenyl (PCB)-induced immunotoxicity is coincident with alterations in the serotonergic system

“…Alternatively, dietary exposure to Aroclor 1254 or coplanar PCB 77 altered both TPH level and activity in a number of fish and rodent studies (Khan and Thomas, 2000, 2001, 2004aand b, 2006, suggesting that the coplanar congeners in the Aroclor mixtures played an important role in the observed changes in TPH.…”

“…Unfortunately, no other studies investigating PCB-induced disruptions of the serotonergic system and subsequent effects on immune function have ever been reported. However, PCBinduced alterations in the serotonergic system have been correlated with neuroendocrine disruption (Khan and Thomas, 1997, 2001, 2004a. In these studies, Khan and Thomas (2001) demonstrated that PCB, acting via inhibition of TPH, reduced hypothalamic 5-HT concentrations resulting in an impairment of gonadotrophin-releasing hormone and leutinizing hormone secretion in Atlantic croaker.…”

“…Changes in the synthesis, metabolism, and uptake of 5-HT have been reported to be altered in fish and mammals following sublethal PCB exposure (Morse et al, 1996;Khan and Thomas, 1997, 2001Mariussen and Fonnum, 2001). For example, dietary exposure of Atlantic croaker (Micropogonias unulatus) to Aroclor 1254 (1 mg/kg body weight [BW]) for 30 d suppressed hypothalamic 5-HT levels and reduced tryptophan hydroxylase (TPH; the rate-limiting enzyme in 5-HT synthesis) levels and activity (Khan and Thomas, 1997, 2001, 2004a. Increases in the primary metabolite of 5-HT (i.e., 5-hydroxyindole acetic acid) have also been reported following PCB exposure (Morse et al, 1996;Khan and Thomas, 1997), suggesting an increased rate of 5-HT turnover in PCB-exposed animals.…”

Effect of dietary supplementation of vitamin E, zinc, and chromium supplementation on growth performance and hematological characteristics of broiler chickens

“…Vitamin E is known to be a protective of lipid component of biological membranes as it is considered a major chain-breaking antioxidant. Vitamin E supplementation has been proven to improve growth performance, enhance immunity and restore impaired immunity as well as influence neuro-endocrine functions (Khan and Thomas, 2004). Vitamin E and Se act together in preventing cellular membranes from oxidative degeneration (El Dein et al, 2013).…”