Microcomputer adaptation of the wheel-shaped activity monitor: effects of lindane

Comparison of behavioral, vestibular, and axonal effects of subchronic IDPN in the rat

The effects of subchronic 3,3'-iminodipropionitrile (IDPN) were characterized in the adult Long-Evans male rat. In a preparatory experiment, acute IDPN (890 mg/kg, IP) and intratympanic arsanilic acid caused similar alterations in locomotor activity, rearings, and scores for vestibular impairment. In a second preparatory experiment, IDPN in the drinking water (0%, 0.025%, 0.05%, 0.1%, 0.2%, or 0.4%) caused a concentration-dependent decrease in water intake, but a effective increase in IDPN intake. In the subchronic experiment, rats were exposed to the above concentrations of IDPN for 15 weeks, except the 0.4% group, exposed for only 7 weeks. Effects on body weight, motor activity, vestibular scores, vestibular morphology, and axonal diameter were observed after 0.2% and 0.4% IDPN. Proximal axonopathies but little or no clinical signs or vestibular toxicity followed 0.05% and 0.1% IDPN. We concluded that vestibular hair cell loss can be induced by subchronic IDPN at doses larger than the axonopathic doses, and that the vestibular toxicity, not the axonopathy, is responsible for the gross changes in behavior characterizing IDPN exposure.

Cerebrospinal dopamine metabolites in rats after intrastriatal administration of 6-hydroxydopamine or 1-methyl-4-phenylpyridinium ion

Dopamine (DA) and its main cerebral metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured in striatum and cerebrospinal fluid (CSF) from cisterna magna in rats bilaterally lesioned by intrastriatal administration of 6-hydroxydopamine (6-OHDA) or 1-methyl-4-phenylpyridinium ion (MPP+). 6-OHDA caused a progressive lesion in striatum that is only moderately reflected in the decrease in dopamine metabolite concentration in CSF. MPP+ caused an acute but less selective lesion in the dopamine striatal system, as indicated by a significant reduction in striatal GABA content, followed by a slow recovery in dopamine striatal metabolism and content. The locomotor activity was dramatically reduced in both groups 48 hours after the treatment but remained significantly decreased after two months only in 6-OHDA lesioned animals. A positive correlation was found between HVA CSF concentration and striatal DA content in MPP+ lesioned rats, but not in 6-OHDA lesioned rats. It is concluded that the concentration of dopamine metabolites in CSF can be altered only after a severe striatal lesion: reduction of striatal dopamine content below 50% of normal values and involvement of neuronal or non-neuronal elements other than the dopaminergic system, similarly to the lesions caused by MPP+. These results may partly explain why CSF dopamine metabolites concentrations were significantly decreased both in advanced stages of parkinsonism and in other neurodegenerative disorders.

Repeated lindane exposure in the rat results in changes in spontaneous motor activity at 2 weeks post-exposure

Male Wistar rats were given 25 doses of lindane, 10 mg/kg per day, 1 ml/kg p.o. in olive oil, or control vehicle. Two weeks after the last dose, the animals were assessed for modifications in spontaneous motor activity, plus-maze behavior, shuttle-box active avoidance acquisition, brain regional concentrations of biogenic amines and metabolites, and regional [35S]TBPS binding. Rats treated with lindane showed an increase in spontaneous motor activity. Although no additional behavioral or neurochemical modifications were found, the changes in activity observed at 2 weeks post-exposure further demonstrate the need to assess for long lasting neurobehavioral sequelae of repeated lindane exposure.