Effect of chronic ceruletide treatment on dopaminergic neurotransmitters, receptors and their mRNAs in the striatum of rats with dyskinesia induced by iminodipropionitrile

Vitamin D3 improves iminodipropionitrile-induced tic-like behavior in rats through regulation of GDNF/c-Ret signaling activity

Children with chronic tic disorders (CTD), including Tourette syndrome (TS), have significantly reduced serum 25-hydroxyvitamin D [25(OH)D]. While vitamin D3 supplementation (VDS) may reduce tic symptoms in these children, its mechanism is unclear. The study aim was to investigate the effects and mechanisms of vitamin D deficiency (VDD) and VDS on TS model behavior. Forty 5-week-old male Sprague-Dawley rats were randomly divided into (n = 10 each): control, TS model, TS model with VDD (TS + VDD), or TS model with VDS (TS + VDS; two intramuscular injections of 20,000 IU/200 g) groups. The VDD model was diet-induced (0 IU vitamin D/kg); the TS model was iminodipropionitrile (IDPN)-induced. All groups were tested for behavior, serum and striatal 25(OH)D and dopamine (DA), mRNA expressions of vitamin D receptor (VDR), glial cell line-derived neurotrophic factor (GDNF), protooncogene tyrosine-protein kinase receptor Ret (c-Ret), and DA D1 (DRD1) and D2 (DRD2) receptor genes in the striatum. TS + VDD had higher behavior activity scores throughout, and higher total behavior score at day 21 compared with TS model. In contrast, day 21 TS + VDS stereotyped behavior scores and total scores were lower than TS model. The serum 25(OH)D in TS + VDD was < 20 ng/mL, and lower than control. Striatal DA of TS was lower than control. Compared with TS model, striatal DA of TS + VDD was lower, while in TS + VDS it was higher than TS model. Furthermore, mRNA expression of VDR, GDNF, and c-Ret genes decreased in TS model, and GDNF expression decreased more in TS + VDD, while TS + VDS had higher GDNF and c-Ret expressions. VDD aggravates, and VDS ameliorates tic-like behavior in an IDPN-induced model. VDS may upregulate GDNF/c-Ret signaling activity through VDR, reversing the striatal DA decrease and alleviating tic-like behavior.

Dual ameliorative effects of Ningdong granule on dopamine in rat models of Tourette's syndrome

Dopamine (DA) is a key neuromodulator in the brain that supports motor and cognitive functions. Here, we use apomorphine (Apo) and 3,3'-iminodipropionitrile (IDPN) to develop two rat models of Tourette's syndrome (TS), a common neuropsychiatric disorder characterized by stereotyped repetitive involuntary tics. The models enabled the assessment of unique ameliorative effects of Ningdong granule (NDG), a traditional Chinese medicine (TCM) preparation dedicated to the treatment of TS, on the striatal DA content of rats. By using high-performance liquid chromatography (HPLC), we found that long-term administration of NDG could, at least partially, restore the striatal dopamine alterations, either by increasing them after IDPN treatment or by decreasing them after Apo treatment. Taken together, our data indicated that NDG could ameliorate the abnormal striatal DA content dually, and the unique therapeutic property may be meaningful for the treatment of TS.

Dual regulating effects of gastrodin on extracellular dopamine concentration in rats models of Tourette's syndrome

PURPOSE

Evaluate the dual regulating effects of gastrodin on striatal extracellular dopamine (DA) concentration in Tourette's syndrome (TS) rat models, and explore the underlying pharmacological mechanisms.

MATERIALS AND METHODS

Seventy Wistar rats were randomly divided into control group and TS model group. The former was intraperitoneally injected with saline (0.9%), while in the later, the rats were injected with Apomorphine (Apo) and 3,3'-iminodipropionitrile (IDPN) respectively to manipulate two kinds of TS rat models. Both Apo and IDPN induced rats were further assigned to three conditions, and the related rats were treated respectively by oral gavage with saline, gastrodin and Haloperidol (Hal). Data of stereotypy of the rats were collected. After 8 weeks, the extracellular content of DA and HVA in striatum were examined by intracerebral microdialysis and follow-up high-performance liquid chromatography (HPLC), and the expression of dopamine transporter (DAT) was probed by Western blot.

RESULTS

Gastrodin improved the stereotyped behaviors in TS rats. Furthermore, it down-regulated the elevated striatal extracellular DA concentration in Apo-induced rats and up-regulated the decreased DA content in the rats exposed to IDPN. Meanwhile, a dramatic down-regulation was detected in DAT protein expression in Apo + GAS group, while an opposite profile was showed in the IDPN + GAS group.

CONCLUSIONS

The dual regulating effects of gastrodin on extracellular DA level have been established, and the related mechanisms would be the dual regulating effects of gastrodin on the expression of DAT, a glycoprotein in the regulation of the extracellular DA concentration.

Gastrodin ameliorates memory deficits in 3,3'-iminodipropionitrile-induced rats: possible involvement of dopaminergic system

3,3'-Iminodipropionitrile (IDPN), one of the nitrile derivatives, can induce neurotoxicity, and therefore cause motor dysfunction and cognitive deficits. Gastrodin is a main bioactive constituent of a Chinese herbal medicine (Gastrodia elata Blume) widely used for treating various neurological disorders and showed greatly improved mental function. This study was designed to determine whether administration of gastrodin attenuates IDPN-induced working memory deficits in Y-maze task, and to explore the underlying mechanisms. Results showed that exposure to IDPN (150 mg/kg/day, v.o.) significantly impaired working memory and that long-term gastrodin (200 mg/kg/day, v.o.) could effectively rescue these IDPN-induced memory impairments as indicated by increased spontaneous alternation in the Y-maze test. Additionally, gastrodin treatment prevented IDPN-induced reductions of dopamine (DA) and its metabolites, as well as elevation of dopamine turnover ratio (DOPAC + HVA)/DA. Gastrodin treatment also prevented alterations in dopamine D2 receptor and dopamine transporter protein levels in the rat hippocampus. Our results suggest that long-term gastrodin treatment may have potential therapeutic values for IDPN-induced cognitive impairments, which was mediated, in part, by normalizing the dopaminergic system.

Expression of neurotransmitter genes in motor regions of the dyskinetic rat after iminodipropionitrile

Rats treated with iminodipropionitrile develop a neurobehaviour syndrome with dyskinesia. Searching for the molecular correlates, we have examined the expression of selected genes involved in neurotransmission in motor regions using hybridization histochemistry. Frontal cortical and thalamic vasoactive intestinal peptide (VIP) expression, and striatal dynorphin, enkephalin (ENK) and substance P expression were increased. No change in cortical cholecystokinin (CCK), ENK, glutamic acid decarboxylase (GAD) and somatostatin (SRIF) expression, in striatal GAD, SRIF, nitric oxide synthase (NOS) and guanylate cyclase expression, and in thalamic CCK, GAD and thyrotropin-releasing hormone expression was found. NOS expression in the subthalamic nucleus as well as tyrosine hydroxylase, GAD and CCK expression in the substantia nigra were unchanged. These results confirm the involvement of striatal projection neurons in dyskinesia and suggest a novel role for VIP.

Effects of repeated cyclosporin A administration on iminodipropionitrile-induced dyskinesia and TRE-/CRE-binding activities in rat brain

To clarify the involvement of immunophilin ligands in the pathogenesis and pathophysiology of dyskinesia, we examined the effects of repeated administration of cyclosporin A (CsA) on rat dyskinesia induced by repeated injection of iminodipropionitrile (IDPN 100 mg/kg, i.p., for 7 days). The addition of CsA treatment (5 mg/kg, s.c., 1 h before each IDPN injection) exacerbated IDPN-induced dyskinesia. In the group treated with both CsA and IDPN, the concentration of dopamine was significantly increased in the striatum and nucleus accumbens compared with the group treated with IDPN alone. Furthermore, in the electrophoretic mobility shift assay, the injection of CsA + IDPN increased binding activities of transcription factors to the TPA (12-O-tetradecanoylphorbol-13-acetate)-responsive element (TRE) and to the cAMP response element (CRE) in the striatum and nucleus accumbens, compared with those in rats treated with IDPN alone. The levels of D1-receptor mRNA in the striatum were significantly decreased in the IDPN-treated rats but were at the control level in the rats given CsA + IDPN. These findings suggest that the behavioral aggravation of the IDPN-induced dyskinesia caused by CsA administration may be due to the acceleration of the pre- and post-synaptic dopaminegic systems via activation of transcription factors which bind upstream to tyrosine hydroxylase and D1-receptor genes, and that the immunophilin binding agents such as CsA are involved in this aggravated dyskinesia.

Cysteamine attenuates iminodipropionitrile (IDPN) induced dyskinesia in rats

The present investigation was undertaken to study the effect of cysteamine on experimental dyskinesia in rats. The movement disorders were produced by intraperitoneal administration of iminodipropionitrile (IDPN) in the dose of 100 mg/kg per day for 11 days. Cysteamine was administered (i.p.), daily 30 minutes before IDPN in the doses of 25 mg/kg, 50 mg/kg and 100 mg/kg bodyweight in three different groups of rats. Twenty four hours after the last dose of IDPN, animals were observed for neurobehavioural changes including vertical and horizontal head weaving, circling, backwalking, grip strength and righting reflex. Immediately after behavioural studies brain specimens were collected for analysis of vitamin E and total glutathione levels. The results of behavioural studies showed that co-treatment with cysteamine protected rats against IDPN-induced dyskinesia. Our biochemical studies showed that IDPN produced a depletion of vitamin E in cerebrum, cerebellum and brain stem. Concomitant treatment with cysteamine in doses of 50 and 100 mg/kg attenuated IDPN-induced decrease in vitamin E in cerebrum and cerebellum. There was a significant decrease in cerebral glutathione in IDPN treated rats, which was attenuated by cysteamine. No significant change was observed in the glutathione levels in cerebellum and brain stem. Further studies are deemed necessary to elucidate the mode of action of cysteamine and to determine therapeutic and/or prophylactic value of this drug in the treatment of movement disorders.

Increased Cu/Zn superoxide dismutase-like immunoreactivity in the swollen axons of rats intoxicated chronically with beta,beta'-iminodipropionitrile

Demonstration of a genetic linkage between the Cu/Zn superoxide dismutase (SOD1) gene and familial amyotrophic lateral sclerosis (ALS) has aroused interest in the role of SOD1 in spinal motoneuronal death. We used chronically beta,beta'-iminodipropionitrile (IDPN)-intoxicated rats as a model of ALS and investigated SOD1 changes in the spinal cord by immunocytochemical and in situ hybridization techniques. Compared with control rats, SOD1-like immunoreactivity (SOD1-IR) increased in swollen axons of the proximal spinal roots, but not in motoneuronal and dorsal root ganglion neuronal cell bodies where SOD1 gene transcription did not increase. The present data indicate that treatment with IDPN induces accumulation of SOD1 in the swollen axons by blocking slow axonal flow, suggesting the possibility that increased SOD1-IR in ALS is induced by axonal flow blockade.

Neuropeptide levels in discrete brain regions in the iminodipropionitrile-induced persistent dyskinesia rat model

To clarify the role of neuropeptides in dyskinesia induced by iminodipropionitrile (IDPN), the levels of five representative neuropeptides were examined in discrete regions of the rat brain 4 weeks after intraperitoneal injection of IDPN. The five neuropeptides examined were methionine-enkephalin (Met-Enk), substance P (SP) and somatostatin, which are closely related to extrapyramidal function, and thyrotropin-releasing hormone (TRH) and cholecystokinin octapeptide (CCK-8), which are closely related to the neural mechanism of the dopamine system. IDPN pretreatment significantly increased Met-Enk in the basal ganglia but not SP or somatostatin; however, all three neuropeptide levels were increased in the hindbrain. In IDPN-treated rats, TRH and CCK-8 levels were increased in the nucleus accumbens, and the frontal cortical CCK-8 level was extremely increased. These findings, together with previous reports, suggest that neuropeptides in the basal ganglia, hindbrain and cerebral cortex play important roles in the manifestation of dyskinetic symptoms.