Table 4.

Effects of pyrethroid pesticides on tau protein

Type of study	Sample	Type of pesticide	Exposure data	Tau phosphorylation	GSK-3β	PP2A	Other mechanisms	Ref.
Experimental studies	Sprague-Dawly rats	Deltamethrin	Concentration: 12.5 mg/kg. Exposure time for 28 d	Increased	Increased	Decreased	Increased phosphorylation of tau was observed in Ser198/199/202, Thr205 and Ser404	[32]
Experimental studies	Wistar rats	Cyfluthrin, imiprothrin, prallethrin	Concentrations:25%, 50% and 75%. Exposure time of 45 d	Increased	Increased	Decreased	Higher immunoreactivity of tau occurred in the hippocampus with high exposures to Ps. For medium and low doses, low immunoreactivity occurred. On the other hand, the activity of GSK- 3β was increased, while that of PP2A 2 was decreased	[34]
Experimental studies	Wistar rats	Cypermethrin	Concentration: 10 mg/kg and 25 mg/kg. Exposure time for 2, 3 and 6 wk	Increased	Increased	NA	In weaned exposed rats, tau phosphorylation increased in frontal cortex and hippocampus. This was induced by an increase in GSK-3β activity. Furthermore, increased neuroinflammation was observed with increased production of IL-1β	[69]
Review studies	Multiple studies	Ps	NA	Increased	Increased	NA	Exposure to Ps induced increased kinase activity, thereby increasing the phosphorylation of tau protein	[62]

Ps: Pyrethroid; IL: Interleukin; GSK-3β: Glycogen synthase kinase 3 beta; PP2A: Protein phosphatase-2A; NA: Not available.