Possible mechanism of bamboo shoots (Bambusa balcooa) induced thyroid disruption – An in vitro study

Abstract

Endemic goitre and associated iodine deficiency disorders (IDDs) are a major concern in public health even in the period of post salt iodization in many regions. Among others the consumption of cyanogenic plants found responsible for the persistence of such diseases. Bamboo shoots (BS) is one such cyanogenic plant food that caused disruption of certain thyroid hormone synthesizing regulatory element as has already been reported in our earlier study. In this investigation the possible mechanism of thyrocytes disruption along with interruption of thyroid hormone biosynthesis by BS has been worked out. Commonly consumed BS, Bambusa Balcooa Roxb (BBR) water extract was analysed by GC MS; three doses below IC50 were administered to thyrocytes in culture with and without iodine. Expressions of thyroglobulin (Tg), pendrin (PDS) and monocarboxylate transporter 8 (MCT8) were evaluated in thyrocytes with cell cycle analysis, reactive oxygen species (ROS) generation, DNA oxidation and apoptotic regulation through Bax, Bcl-2 and p53. Phytochemical analysis of BBR extract revealed the presence of precursors and metabolic end products of cyanogenic glycosides. Dose dependent decrease in expression of Tg and PDS with concomitant decrease in gene expression of these with MCT8 were observed. Increased ROS, DNA oxidation and associated imbalance were found through increased Bax and p53 with decreased Bcl-2 that perturbed thyrocytes cell cycle. Cyanogenic constituents of BBR generates ROS associated oxidative changes in thyrocytes with DNA damage and oxidation and cell cycle disruption followed by inhibition of thyroid hormone synthesizing regulatory elements; addition of extra iodine showed partial prevention.

Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels

“…Additionally, the in vitro study of Sarkar et al, showed that cyanogenic constituents in bamboo shoots generate reactive oxidative species that contribute to oxidative DNA damage and cell cycle disruption. This is followed by the inhibition of regulatory elements that synthesize thyroid hormones [ 138 , 139 ].…”

Thyroid Functions in Bamboo-Shoots Consuming Children of Tripura, North-east India

“…(ii) children's maximal levels of TSH and FT 3 in Unakoti where BS consumption was highest and iodine intake was adequate (Table 1) -suggests that BS might have interfered with thyroid function in studied children. However, it has already been reported that the antithyroidal action of BS can be mitigated partially by iodine [49,51].…”

Perchlorate, nitrate, and thiocyanate: Environmental relevant NIS-inhibitors pollutants and their impact on thyroid function and human health

“…However, although previous studies indicated that the co-exposure to perchlorate and thiocyanate is potentially deleterious to the thyroid function in adults and in susceptible individuals, as pregnant women, fetus, and newborns, the effects of thiocyanate per se in the thyroid are still controversial in humans (27,30,31,76) Finally, the molecular mechanisms involved in the thiocyanate regulation of thyroid function are not completely understood. Studies using primary thyroid cells cultures exposed to plant extracts rich in thiocyanate demonstrated an increased production of reactive oxygen species, induced cell injury and DNA damage, decreased gene expression and activity of proteins involved in the synthesis of thyroid hormones (77,78). However, the direct effects of thiocyanate per se in the thyrocytes have never been reported.…”