cell

Aluminium induced biphasic effects

Aluminium

is

capable

of

producing

biphasic

effect

in

diverse

systems. A high dose of aluminium, has been observed, to decrease protein

synthesis

and

a

lower

dose

increased

protein

synthesis.

In

rabbits

exposed to aluminium, brain protein synthesis has been reported to be

increased at lower dose and decreased at higher dose (22,23). Letterier

et al (15) have shown that low

concentration

of

aluminium

stimulates

associated

phosphorylation

of

neurofilament

subunits

by

neurofilament

protein kinase, followed by complete inhibition of the reaction at higher

aluminium concentration.

Yokel (34) has shown that lactating rabbits receiving aluminium lactate

(25,100,400 or800 µM aluminium/kg body weight) between days 4 and 29

postpartum resulted in biphasic effect on offspring weight gain. Lower

concentration (25 and 100 µM) of aluminium exposure resulted in greater

weight

gain

and

higher

concentration

(400

and

800

µM)

of

aluminium

suppressed the weight gain. Leiberherr et al (14) have reported that in

osteoblasts, aluminium stimulates mitogenesis at lower concentration and

inhibits cell growth and mitosis at higher concentration. Microinjection

of aluminium chloride in single muscle fibers of the barnacle Balanus

nubiliusproduces biphasic effect on sodium efflux, sodium efflux being

inhibited

following

transitory

stimulation

(4).

The

studies

reported

reveal aluminium induced biphasic effect

in

different

systems.

Though

aluminium has been suggested as a cholinotoxin and aluminium intoxicated

rat as a possible animal model for senile dementia of Alzheimer's type