Increased number of locus ceruleus noradrenergic neurons in the convulsive mutant quaking mouse.

Noradrenergic cell bodies in the locus ceruleus of the convulsive mutant quaking mouse and the control of the same strain were visualized using histofluorescence and tyrosine hydroxylase-like immunoreactivity. Cell counts performed with the two techniques gave closely similar results within each strain, indicating a 50% increase in the number of noradrenergic neurons in the midportion of the mutants' locus ceruleus when compared to the controls. This result gives histological support to the increased noradrenergic neurotransmission previously described in the brain of this mutant. Thus, the abnormally high activity of the noradrenergic system appears to be a primary effect of the mutation, associated with the convulsions of this animal model of epilepsy.