Influence of cestode parasites (Hymenolepis spp.) on Metallothionein-1 levels in Cadmium-exposed rats (Rattus spp.)

Date

4-2018

Abstract

Metallothioneins (MTs) are low-molecular weight and sulfhydryl rich proteins which are detected in basal levels from mammalian tissues. MTs are reported to be involved in metalloregulatory processes. In this study, the prevalence of Hymenolepis spp. in rats and their effects on MT levels in the hosts were investigated. Rattus spp. were collected in various areas adjacent to Mt. Makiling in Los Baños, Laguna, and the cadmium and metallothionein concentrations of their tissues and cestode parasites, Hymenolepis spp., were determined. Results showed a significant difference in mean cadmium concentrations among various rat tissues where highest concentration was observed in kidney (1.93 ± 0.32 mg/kg), followed by intestine (0.87 ± 0.14 mg/kg), liver (0.85 ± 0.16 mg/kg) and muscle (0.56 ± 0.16 mg/kg); while cadmium concentration of Hymenolepis spp. was 1.36 ± 0.26 mg/kg. Also, the bioaccumulation factor (BAF) of Hymenolepis spp. was found to be low, which was evident in the result that there was no significant difference in cadmium levels between infected (1.05 ± 0.14 mg/kg) and uninfected rats (1.71 ± 0.45 mg/kg). However, metallothionein concentration of uninfected rats (8.66 ± 1.78 ng/L) was significantly higher compared to the infected ones (4.29 ± 0.88 ng/L), suggesting that slight changes in cadmium concentration due to parasite absorptive capacity, could lead to significant changes in MT levels. Thus, this study provides evidence that although the parasite has low bioaccumulation capacity, their presence or absence could influence the protective role of metallothionein in the hosts. This highlights the limit of the use of MT as biomarker of metal pollution in field monitoring if parasitism is not taken into account, leading to false-negative results. Nevertheless, metallothionein can be considered as sensitive and efficient biomarker of cadmium levels in rats and with regards to assessing the effects of pollution and parasitism on host's physiology.

Document Type

Master Thesis

Degree

Master of Science in Zoology

College

Graduate School (GS)

Adviser/Committee Chair

Vachel Gay V. Paller

Committee Member

Maria Claret L. Tsuchiya, Ma. Carmina C. Manuel

Language

English

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