Ma. Mccoy et al., Regional brain monoamine concentrations and their alterations in bovine hypomagnesaemic tetany experimentally induced by a magnesium-deficient diet, RES VET SCI, 69(3), 2000, pp. 301-307
Monoamines are important brain neurotransmitters. An investigation was carr
ied out to determine if hypomagnesaemic tetany was associated with alterati
ons in regional brain monoamine concentrations in bovines. The results, est
ablished in cows with normal magnesium status, demonstrated that regional d
ifferences existed in the distribution and concentration of brain monoamine
s in the adult bovine, which were similar to those in other species. In mag
nesium-deficient cows, severe hypomagnesaemia and lowered cerebrospinal flu
id (CSF) magnesium concentrations were associated with significant alterati
ons in monoamine concentrations in some brain regions. Alterations in 3,4-d
ihydroxyphenylalanine (DOPA) and dihydroxyphenylacetic acid (DOPAC) concent
rations in the corpus striatum, and dopamine (DA) in the cerebral cortex an
d cerebellum were recorded. These regions play an important role in both vo
luntary and involuntary motor function, and therefore these alterations may
play a role in the aetiology of hypomagnesaemic tetany. However, there was
no significant change in DA concentrations in the corpus striatum (the mai
n dopaminergic region in the brain) associated with hypomagnesaemia. In add
ition, a significantly lower norepinephrine (NE) concentration in the corpu
s striatum of hypomagnesaemic animals was also recorded. Norephinephrine is
generally excitatory and therefore lowered NE concentrations would be expe
cted to result in depression rather than stimulation of motor function. (C)
2000 Harcourt Publishers Ltd.