Hippocampal integrity is essential for cognitive functions. On the other hand, induction of metallothionein (MT) by ZnSO4 and its role in neuroprotection has been documented. The present study aimed to explore the effect of MT induction on carmustine (BCNU)-induced hippocampal cognitive dysfunction in rats. A total of 60 male Wistar albino rats were randomly divided into four groups (15/group): The control group injected with single doses of normal saline (i.c.v) followed 24 h later by BCNU solvent (i.v). The second group administered ZnSO4 (0.1 µmol/10 µl normal saline, i.c.v, once) then BCNU solvent (i.v) after 24 h. Third group received BCNU (20 mg/kg, i.v, once) 24 h after injection with normal saline (i.c.v). Fourth group received a single dose of ZnSO4 (0.1 µmol/10 µl normal saline, i.c.v) then BCNU (20 mg/kg, i.v, once) after 24 h. The obtained data revealed that BCNU administration resulted in deterioration of learning and short-term memory (STM), as measured by using radial arm water maze, accompanied with decreased hippocampal glutathione reductase (GR) activity and reduced glutathione (GSH) content. Also, BCNU administration increased serum tumor necrosis factor-alpha (TNFα), hippocampal MT and malondialdehyde (MDA) contents as well as caspase-3 activity in addition to histological alterations. ZnSO4 pretreatment counteracted BCNU-induced inhibition of GR and depletion of GSH and resulted in significant reduction in the levels of MDA and TNFα as well as the activity of caspase-3. The histological features were improved in hippocampus of rats treated with ZnSO4 + BCNU compared to only BCNU-treated animals. In conclusion, MT induction halts BCNU-induced hippocampal toxicity as it prevented GR inhibition and GSH depletion and counteracted the increased levels of TNFα, MDA and caspase-3 activity with subsequent preservation of cognition.

The present study was carried out to evaluate the effect of exogenously administered metallothionein (MT) against carmustine (BCNU)-induced lung toxicity in rats. A total of 60 rats were randomly divided into four groups (15/group): control group in which the animals received 0.5 ml physiologic saline containing 10% ethanol (IP) weekly, MT-administered group in which rats received MT (30 micromol/kg, IP) weekly, BCNU-administered group in which rats received BCNU (5 mg/kg, IP) weekly and MT + BCNU group in which rats received weekly doses of BCNU (5 mg/kg, IP) followed 24 h later by MT (30 micromol/kg, IP). At the end of the experiment (after 6 weeks), lung histological changes, collagen staining, the activity of glutathione reductase (GR) and contents of reduced glutathione (GSH) and hydroxyproline (Hpr) in the lung as well as serum level of tumor necrosis factor-alpha (TNF-alpha) were evaluated. The obtained data revealed that BCNU induced pathological changes and markedly increased lung collagen and level of Hpr but decreased GSH content and GR activity and increased serum TNF-alpha compared to both control and MT-administered rats. Administration of MT + BCNU markedly improved histological features and decreased staining of collagen along with increased GR activity, GSH content but decreased level of Hpr in lung tissue as well as decreased serum level of TNF-alpha compared with BCNU-treated rats. Based on our results, it is possible to postulate that exogenous MT can act against BCNU-induced lung toxicity by a mechanism related, at least in part, to its ability to decrease oxidative stress and fibrosis.

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