Catecholamine degradation by monoamine oxidase in locus coeruleus neurons of the rat. An immunohistochemical study

Effects of hypomagnetic field on noradrenergic activities in the brainstem of golden hamster

Previous studies found that elimination of the geomagnetic field (GMF) interferes with the normal brain functions, but the underlying mechanism remains unknown. The present study examined the effects of long-term exposures to a near-zero magnetic environment on the noradrenergic activities in the brainstem of golden hamsters. Both the content of norepinephrine (NE) and the density of NE-immunopositive neurons in the tissue decreased significantly after the treatment, and the effects could be progressive with time. These variations may substantially contribute to behavioral and mood disorders reported in other studies when animals are shielded from the GMF.

Effects of isatin on rotational behavior and DA levels in caudate putamen in Parkinsonian rats

Isatin was a potent endogenous monoamine oxidase (MAO) inhibitor that is more active against MAO-B than MAO-A. The acute effects of isatin on apomorphine (APO)-induced rotations were evaluated in Parkinsonian rats induced by 6-hydroxydopamine (6-OHDA) lesion. Furthermore, the effects of isatin on DA release in caudate putamen (CPu) of model and normal rats were monitored using fast cyclic voltammetry (FCV). The contents of monoamine transmitters and their metabolites in CPu of model and normal rats were also analyzed by high performance liquid chromatography with electrochemical detection after administration of isatin. Here we show that isatin (100 mg/kg, i.p.) apparently inhibited APO-induced rotations of Parkinsonian rats to 39.1+/-3.7% of the control (n=12), while it had no apparent effects on electrical stimuli-induced DA release either in normal rats or in model rats. In addition, the content of 5-hydroxytryptamine but not DA was increased in both normal rats and model rats after isatin (100 mg/kg, i.p.) was administered (P<0.01, n=6). The content of 5-hydroxyindole acetic acid was not changed. These results suggest that isatin cannot increase DA levels in rat CPu. Therefore, the effects of isatin on APO-induced rotations of our Parkinsonian rats could not attribute to its inhibition of DA catabolism as a MAO inhibitor.