Effects of bromelain on motor responses following intra-medial forebrain bundle 6-OHDA injection in rat model of parkinsonism.

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. The conventional therapeutic measures which include the widely used L-DOPA therapy, are inefficient especially when dopamine loss is severe, and the physical symptoms are full blown. Since neuroinflammation is a core feature of PD, this raised the question of whether early treatment with an anti-inflammatory agent may provide a more efficient intervention for PD. In this study, we investigated the effect of bromelain (an anti-inflammatory drug) on motor responses and dopamine levels in a parkinsonian rat model. Male Sprague-Dawley rats were lesioned stereotaxically with the neurotoxin 6-OHDA. The anti-inflammatory agent, bromelain (40 mg/kg i.p) was used to treat a subset of the rats prior to or 24 h post 6-OHDA lesion. Locomotor activity was assessed after 6-OHDA injection, using the cylinder and step tests. The cortical and striatal concentrations of dopamine were also measured. 6-OHDA injection resulted in marked motor impairment which was prevented by pretreatment with bromelain prior to the lesion. Also, the injection of 6-OHDA into the medial forebrain bundle resulted in a significant reduction in dopamine concentration in the striatum and PFC. Bromelain treatment did not alter the suppression of cortical and striatal dopamine levels. Pre-treatment with bromelain reduced the motor dysfunction in the parkinsonian rat model of PD. The efficacy of treatment with bromelain does not appear to be via preservation of the dopaminergic system. The efficacy of bromelain in 6-OHDA injected rats still remains unclear.

DTI-based deterministic fibre tracking of the medial forebrain bundle.

BACKGROUND: Deep brain stimulation (DBS) of the medial forebrain bundle (MFB) was reported to reduce symptoms in psychiatric disorders. The aim of our study was to find standardised parameters for diffusion tensor imaging (DTI) based fibre tracking to reliably visualise the MFB. METHODS: Twenty-two cerebral hemispheres in 11 patients were investigated. Three different regions of interest (ROIs) were defined as seed regions for fibre tracking: the ipsilateral and contralateral superior cerebellar peduncle (SCP) and the nucleus raphe dorsalis (NRD). From each seed region the fibres were followed separately through the ventral tegmental area (VTA = second ROI) and their further courses and volumina were documented and compared. Minimal fibre length was set at 30 mm and the FA threshold at 0.12. RESULTS: The fibre tracts starting in seed regions in the ipsilateral SCP and the NRD follow a similar course along the lateral wall of the third ventricle (hypothalamus) and the anterior limb of the internal capsule (ALIC) to inferior fronto-medial brain areas. These fibres are in accordance with the course of the MFB as described in various anatomical atlases. Consistently, a branch leaves the main fibre tract laterally to take a course through the capsula externa to the temporo-parietal cortex. Fibre tracts starting from the contralateral SCP follow a more superior and lateral course, including the dentato-rubro-thalamic and the pyramidal tract. CONCLUSIONS: Deterministic fibre tracking with standardised ROIs provides constant and reproducible delineations of the medial forebrain bundle. Its visualisation might help to adjust targeting in DBS for psychiatric disorders.

Potentiation of parkinsonian symptoms by depletion of locus coeruleus noradrenaline in 6-hydroxydopamine-induced partial degeneration of substantia nigra in rats.

Parkinson's disease is characterized not only by a progressive loss of dopaminergic neurons in the substantia nigra but also by a degeneration of locus coeruleus noradrenergic neurons. The present study addresses the question of whether a partial neurodegeneration of dopaminergic neurons using 6-hydroxydopamine in rat, not sufficient to produce motor disturbances, is potentiated by prior selective denervation of locus coeruleus noradrenergic terminal fields using N-ethyl-2-bromobenzylamine. Two types of denervations, one causing dopamine deficiency alone and the other causing noradrenaline and dopamine deficiency, were performed. Noradrenaline, 5-hydroxytryptamine, 5-hydroxyindole acetic acid, dopamine and its metabolites were analysed in various brain regions. Behaviour was evaluated by catalepsy tests and activity box. N-ethyl-2-bromobenzylamine selectively depleted noradrenaline from neurons of locus coeruleus origin. Decreased dopamine content in the striatum, substantia nigra and pre-frontal cortex was observed after dopaminergic lesion with 6-hydroxydopamine (42.9%). Additional locus coeruleus noradrenaline depletion with N-ethyl-2-bromobenzylamine aggravated the dopamine depletion (61.2%). The lesion in the noradrenergic and dopaminergic neurodegenerated group was not sufficient to induce consistent catalepsy and akinesia. However, after a subthreshold dose of haloperidol (0.1 mg/kg), the expression of catalepsy and akinesia was strong in the dual-lesioned group and less in the 6-hydroxydopamine-lesioned group. These results indicate that denervation of locus coeruleus noradrenergic terminals with N-ethyl-2-bromobenzylamine potentiates the 6-hydroxydopamine-induced partial dopaminergic neurodegeneration and parkinsonian symptoms. Based on the present findings and existing reports, it can be concluded that noradrenergic neurons of locus coeruleus have neuromodulatory and neuroprotective properties on the dopaminergic neurons of basal ganglia and that noradrenergic degeneration may contribute to the aetiology and pathophysiology of Parkinson's disease.

Neuroleptic catatonia and its relationship to psychogenic catatonia.

Neuroleptics are among those pharmacological agents that can cause a nonpsychogenic catatonic state. Neuroleptic malignant syndrome (NMS) is marked by a change in state of consciousness, ranging from withdrawal through stupor to coma. In addition, it is characterized by autonomic dysfunction, hyperthermia, mutism, and rigidity. It is included in the differential diagnosis of the catatonic syndrome. Evidence is reviewed to suggest that agents responsible for improving NMS act on the dopamine (DA) gamma aminobutyric acid (GABA) connections in the mesostriatal and mesolimbic systems and also in the hypothalamus. In addition, based on symptomatology, pathophysiology, and therapeutic mechanisms, the relationship between nonpsychogenic neuroleptic-induced catatonia and psychogenic catatonia is examined.

Intrahypothalamic terminals of stress conducting fibers.

Surgical stress did not elevate plasma corticosterone level in rats with bilateral surgical transection of the lateral retrochiasmatic area (RCAL). After RCAL transections light and electron microscopic terminal degeneration was observed in both the external and the internal layers of the median eminence as well as in the arcuate and ventromedial nuclei. Incisions lateral to the medial forebrain bundle did not prevent the stress-induced rise in plasma corticosterone level and were not followed by degeneration in the median eminence. Transection of the medial forebrain bundle rostral or caudal to the RCAL caused degeneration in both the median eminence and the arcuate nucleus.

[Effect of damage to the zone of the medial forebrain bundle and preoptic area on the activiy of a penicillin-induced epileptiform focus (phenomenon of the hyperactive determinant dispatch station)]. / Vliianie povrezhdeniia zony medial'nogo puchka perednego mozga i preopticheskoi oblsti na aktivnost' vyzvannogo penitsillinom épileptiformnogo ochaga (k fenomenu giperaktivnoi determiniruiushchei stantsii otpravleniia)

It was shown in experiments on cats under nembutal anesthesia that a lesion of the medial forebrain bundle (MFB) and partly of the preoptic region at the side of local penicillin application on the cerebral cortex (g. suprasylvius medius) results in depression of the epileptiform activity in the penicillin-induced focus, as well as in the secondary "mirror" focus, which appeared in the symmetrical cortex area of the other hemisphere. The MFB lesion at the "mirror" focus side led to depression of the seizure spike potentials in this focus only and did not change the activity in the primary epileptiform one. The described effects are considered from the aspect of the conception on the role of the determinant dispatch station (DDS) in the central nervous system: the primary epileptiform focus plays the role of the hyperactive DDS which induces the secondary focus and determines the character of its activity. The results of the study substantiate a suggestion that the MFB can take part in the modulation of the cortical epileptiform activity.