peroxidation rate could affect the neurons, leading to depletion of AChE

activity.

The effect of aluminium on AChE activity can be due to the direct effect

of aluminium on the enzyme itself. Gulya et al (12) have suggested that

increase

in

AChE

activity

could

reflect

an

allostearic

interaction

between aluminium accumulated

and

the

peripheral

anionic

site

of

the

also

enzyme

implies

molecule.

As

the

neuro

degenerative

effect

of

aluminium

degradation

of

at

least

a

part

could

of

the

membrane

bound

AChE,

AChE

aluminium

at

higher

concentration

produce

a

decrease

in

activity. Therefore different mechanisms may result in biphasic effect.

Aluminium has been shown to produce changes in the membrane rigidity and

membrane fusion (9,30) and therefore alters membrane structure. Aluminium

can produce changes

in

membrane

fluidity

leading

to

altered

cellular

response which may produce varying cell signals. It has been suggested

that varying cell signals are responsible for

the

biphasic

effect

of

aluminium on cell protein synthesis (23). Therefore it is most likely

that peroxidation induced changes in membrane structures are responsible

for the biphasic effects of aluminium.

Aluminium, in summary, produces biphasic effect by diverse biochemical

processes. Aluminium induced biphasic effect on the cholinergic system

has to be studied in detail in order to understand the exact cause and

mechanism and thus to understand the molecular mechanism of aluminium

neurotoxicity.