L-threo 3,4-dihydroxyphenylserine treatment during mouse perinatal and rat postnatal development does not alter the impact of dietary copper deficiency

Curcumin alleviates arsenic trioxide-induced neural damage in the murine striatal region

RATIONALE

Arsenic-induced neurotoxicity, with dose-dependent effects, is well-documented in rodents. Curcumin (CUR), a cost-effective plant polyphenol, shows neuroprotective effects by modulating oxidative stress, apoptosis, and neurochemistry. This study evaluates curcumin's neuroprotective potential against arsenic trioxide (As2O3) in the mouse striatal region.

METHODS

Healthy adult male mice were chronically administered with varying concentrations of As2O3 (2, 4 and 8 mg/kg bw) alone and along with CUR (100 mg/kg bw) orally for 45 days. Towards the end of the experimental period, the animals were subjected to behavioural paradigms including open field task, novel object recognition, rota-rod, and Morris water maze. Striatal tissues were freshly collected from the animals on day 46 for biochemical analyses (MDA, GPx, and GSH). Additionally, perfusion-fixed brains were processed for morphological observations.

RESULTS

Behavioural study showed an apparent decrease in certain cognitive functions (learning and memory) and locomotor activity in mice exposed to As2O3 compared to controls. Simultaneous treatment of As2O3 (2, 4 and 8 mg/kg bw) and curcumin (100 mg/kg bw) alleviated the As-induced locomotor and cognitive deficits. As2O3 alone exposure also exhibited a significant increase in oxidative stress marker (MDA) and a decrease in antioxidant enzyme levels (GPx, GSH). Morphological alterations were noted in mice subjected to elevated doses of As2O3 (4 and 8 mg/kg bw). However, these changes were reversed in mice who received As2O3 + CUR co-treatment.

CONCLUSIONS

Collectively, our findings indicate that curcumin offers neuroprotection to the striatal region against As2O3-induced behavioral deficits, as well as biochemical and morphological alterations.

Copper deficiency in rodents alters dopamine beta-mono-oxygenase activity, mRNA and protein level

Cu is an essential cofactor for at least twelve mammalian enzymes including dopamine beta-mono-oxygenase (DBM), which converts dopamine (DA) to noradrenaline (NA). Previous studies reported that certain Cu-deficient (Cu-) rat tissues have lower NA and higher DA than Cu-adequate (Cu+) tissues, suggesting that DBM function was impaired. However, in vitro studies suggested that DBM activity is higher in Cu- tissue. Experiments were conducted on adrenal glands (AG), medulla oblongata/pons (MO), vas deferens (VD) and heart (HT) from a single rat experiment to provide data to help clarify this puzzling contradiction. In vitro DBM activity assays showed Cu- samples had significantly higher activity than Cu+ samples in both AG and MO, but not VD. Activity data were confirmed by Western immunoblots. Quantitative real-time PCR demonstrated higher DBM mRNA in Cu- tissues but unaltered levels of several other cuproenzymes and Cu-binding proteins. Previous pharmacological data implied that high DBM was associated with low NA. HPLC analyses confirmed that NA and DA levels in Cu- MO, VD and HT were significantly lower and higher, respectively, than in Cu+ tissues. However, the NA content of AG was not statistically lower. Furthermore there was no correlation between higher DBM mRNA and lower NA in four Cu-tissues. Adequate dietary Cu is essential to support DBM function in vivo but additional studies are needed to determine the mechanism for increased DBM transcription associated with Cu deficiency.

Rodent brain and heart catecholamine levels are altered by different models of copper deficiency

Limiting dopamine beta-monooxygenase results in lower norepinephrine (NE) and higher dopamine (DA) concentrations in copper-deficient Cu- tissues compared to copper-adequate Cu+ tissues. Mice and rat offspring were compared to determine the effect of differences in dietary copper Cu deficiency started during gestation or lactation on catecholamine, NE and DA, content in brain and heart. Holtzman rat and Hsd:ICR (CD-1) outbred albino mouse dams were fed a Cu- diet and drank deionized water or Cu supplemented water. Offspring were sampled at time points between postnatal ages 12 and 27. For both rat and mouse Cu- tissue, NE and DA changes were greater at later ages. Though Cu restriction began earlier in rats than mice in the gestational model, brain NE reduction was more severe in Cu- mice than Cu- rats. Cardiac NE reduction was similar in Cu- rodents in the gestation models. In the lactation model, mouse catecholamines were altered more than rat catecholamines. Furthermore, following lactational Cu deficiency Cu- mice were anemic and exhibited cardiac hypertrophy, Cu- rats displayed neither phenotype. Within a species, changes were more severe and proportional to the length of Cu deprivation. Lactational Cu deficiency in mice had greater consequences than in rats.