Metallothionein levels in willow ptarmigan (Lagopus lagopus) populations with different natural loads of cadmium

Abstract

The tissues of willow ptarmigan in some Norwegian mountain areas contain elevated concentrations of cadmium (Cd). It is not known whether such high Cd levels would have negative impacts in otherwise healthy populations of this species. The aim of the current study was to clarify relationships between hepatic and renal metallothionein (MT) and Cd concentrations in willow ptarmigan to assess effects from this metal. The study reported here was undertaken on willow ptarmigan from the Kongsvoll area, with a naturally high Cd load, and the Essand area, with a naturally low Cd load. Cd values in liver and kidney in willow ptarmigan from Kongsvoll were significantly higher than in willow ptarmigan from Essand. The MT content in both tissues was also highest in willow ptarmigan from Kongsvoll. The MT concentration in kidney was twice that in liver for ptarmigan from both areas and at all times of the year. The MT level in both liver and kidney varied greatly throughout the season, with the highest content in spring (May). The variation was greatest in liver. The total material showed a significant linear relationship between Cd and MT levels in both liver and kidney, but a breakdown of the material into seasons and areas gave a varying degree of significance. MT in willow ptarmigan may be an important mechanism for detoxifying Cd, and populations exposed to high load may “respond” to the loads by increasing MT synthesis in tissues such as liver and kidney. There is no evidence that willow ptarmigan from areas with high natural Cd loads have reached a limit for MT synthesis in either liver or kidney.