Impairment in exploratory behavior is associated with arc gene overexpression in the dorsolateral striatum of rats with nigral injection of l-buthionine sulfoximine

The aims of the present work were to evaluate the exploratory activity in Sprague-Dawley rats, as well as to analyze the nigral and striatal mRNA expression of the plasticity-related genes bdnf and arc after L-buthionine sulfoximine (BSO) injection into substantia nigra compacta. Lesioned rats traveled less distance in open field but did not show a decline in the novel object recognition test. On the other hand, RT-PCR analysis showed overexpression of striatal arc 24 h post-lesion; no significant changes in bdnf expression were observed in nigral or striatal tissue. These results suggest that intranigral BSO injection causes impairment in exploratory behavior in these rats, by affecting locomotion, which is associated with changes in striatal synaptic plasticity.

[Evaluation of the survival of bone marrow mononucleate cells transplanted in a rat model of striatal lesion with quinolinic acid]

INTRODUCTION

Transplant is one of the alternatives available for the treatment of neurodegenerative diseases aimed at replacing the cells lost during the course of the disease. One promising source of cells for the development of transplants could be the mononucleate cells from bone marrow. AIMS. The purpose of this study was to study the capacity of bone marrow mononucleate cells to survive the transplant process, and to search for a method that enables tracking of these cells in vivo once they have been implanted.

MATERIALS AND METHODS

Bone marrow mononucleate cells were extracted from the femur of rats by means of a Ficoll-Hypaque gradient. The cells under study were modified genetically with an adenovirus that expresses the PFV or which are marked with Hoechst dye. The marked cells were implanted in the striatum of rats with lesions caused by quinolinic acid.

RESULTS

The viability of the genetically modified cells was low, whereas that of the cells marked with Hoechst dye was above 90%. The implanted cells survived the transplant at least a month and dispersed away from the site of entry towards the corpus callosum and cortex.

CONCLUSIONS

We consider that the use of Hoechst dye offers more advantages for tracking these cells in vivo. Mononucleate cells have a number of characteristics that allow them to be included as candidate sources of cells for the treatment of neurodegenerative diseases.

[The effects of lesions in the compact part of the substantia nigra on glutamate and GABA release in the pedunculopontine nucleus]

INTRODUCTION

The pedunculopontine nucleus (PPN), co-localized with the mesencephalic locomotor region, has been proposed as a key structure in the physiopathology of Parkinson's disease.

OBJECTIVES

The goal of the present study was to assess if the aminoacid neurotransmitter release in the PPN is modified by the degeneration of dopaminergic cells, from substantia nigra pars compacta in 6-hydroxidopamine (6-OHDA)-lesioned rats. In addition, it was studied the aminoacid neurotransmitter release in the PPN of rats with lesion of the subthalamic nucleus by quinolinic acid (QUIN) (100 nmol) intracerebral injection.

MATERIALS AND METHODS

Rats were assigned to five groups: untreated rats (I) (n = 13), 6-OHDA lesion (II) (n = 11), 6-OHDA + QUIN lesion (III) (n = 9), sham-operated (IV) (n = 10), QUIN, STN (V) lesioned (n = 9). The extracellular concentrations of glutamic acid (GLU) and gamma-aminobutyric acid (GABA) were determined by brain microdialysis and high performance liquid chromatography (HPLC). RESULTS. GLU released in PPN from 6-OHDA lesioned rats (group II), was significantly increased in comparison with the others groups (F(4, 47) = 18.21, p < 0.001). GABA released shows significant differences between experimental groups (F(4, 45) = 12.75, p < 0.001). It was detected a higher valour (p < 0.05) in-group II. The groups III and IV exhibited intermeddle valour (p < 0.001) and groups I and IV (p < 0.001) showed the lower GABA extracellular concentrations. The infusion of artificial cerebrospinal fluid with higher potassium (100 mmol) induced an increase in the GLU and GABA released in all groups, which confirm the neuronal origin of the extracellular content.

CONCLUSION

These results are in agreement with the current model of basal ganglia functioning and suggest the role of STN-PPN projection in the physiopathology of Parkinson's disease.

[Stromal cell transplant in the 6-OHDA lesion model]

INTRODUCTION

A good deal of evidence currently exists to show that transplanting foetal mesencephalic tissue can produce symptomatic benefits both in patients and in disease models. Nevertheless, the technical and ethical difficulties involved in obtaining enough suitable foetal cerebral tissue have been a serious obstacle to its application. Stromal cells derived from bone marrow, due to their potential capacity to generate different types of cells, could be an ideal source of material for cell restoration in neurodegenerative diseases.

AIMS

Our aim was to evaluate the effect of transplanting stromal cells derived from bone marrow on the behaviour of 6-OHDA rats, when they are inserted into the striatum.

MATERIAL AND METHODS

In this study we used rats with a lesion in the substantia nigra induced by 6-hydroxydopamine, divided into several experimental groups. Rotary activity induced by D-amphetamine (5 mg/kg, intraperitoneally) was evaluated before and throughout the three months following the transplant in all the experimental groups, except in the group of healthy controls. Hemiparkinsonian rats received a total of 350 000 foetal ventral mesencephalic cells and 8 x 10(4) stromal cells/microL, which were implanted in the striatum.

RESULTS AND CONCLUSIONS

Animals with stromal cells transplanted in the body of the striatum significantly reduced the number of turns induced by amphetamine (p < 0.05); yet this reduction was not greater than that induced by foetal mesencephalic cell transplants. We were also unable to demonstrate any significant improvement in the motor skills of the forelimbs.

[Lesions in the pars compacta substantiae nigra and the subthalamic nucleus modify the density of muscarinic receptors in different nuclei of the basal ganglia]

INTRODUCTION

Several studies that has focused to the dopaminergic transmission in the basal ganglia in parkinsonian condition, but only a few article has taking into account the imbalance between dopaminergic and cholinergic transmission.

OBJECTIVE

To evaluate the muscarinic cholinergic receptors density in SNc and PPN in the 6-OHDA model.

MATERIALS AND METHODS

Were organized five experimental groups in correspondence to the place of the lesion: I. Non treated rats, II. 6-OHDA lesion in SNc, III. 6-OHDA lesion in SNc + quinolinic acid lesion in NST, IV. Sham operated rats, V. Quinolinic acid in STN. Were obtained coronal sections of 20 microm thickness of SNc and PPN from rats and in these sections was evaluated the muscarinic receptors density through autoradiographic technique with [3H]quinuclidinylbenzilate (QNB) (1.23 nM). The muscarinic antagonist atropine (1 microM) was utilized as non-specific union. The density was evaluated in both hemispheres and the density optical was converted in fentomolas/mg of tissue with base to values obtained from tritium standards.

RESULTS

Significant diminution of the muscarinic receptors density was found in the SNc ipsilateral to the 6-OHDA lesion from experimental groups II (t=2.76; p<0.05) and III (t=4.06; p<0.05). In the group V, was seen a significant increase of muscarinic receptor density in the SNc ipsilateral to the 6-OHDA lesion. The comparison between experimental groups evidenced significant differences among them (F=13.13; p<0.001) with a significant decrease in the density from SNc of groups II and III and significant increase in the density from SNc of group V in comparison of the others groups. In relation to PPN, muscarinic receptors density from right PPN ipsilateral to the 6-OHDA lesion, shown significant differences (F=3.93; p<0.01) between the experimental groups with a significant increase of this variable in the group II.

CONCLUSIONS

These results signal a modification of cholinergic activity after 6-OHDA lesion. The changes in the muscarinic receptors populations located in SNc and PPN could be part of different compensatory mechanisms to attempt ameliorate the imbalance between dopaminergic and cholinergic transmission that it was installed after denervation of nigrostriatal forebrain bundle. The excitotoxic lesion of STN impose a new adjust mechanism for cell from PPN, which could be expressed in the changes of muscarinic cholinergic receptors population at the level of SNc.

[The pedunculopontine nucleus. A structure involved in motor and emotional processing]

INTRODUCTION

There is currently a growing interest for conducting studies into the electrical and neurochemical activity of the pedunculopontine nucleus (PPN) due to the privileged position occupied by this structure in the flow of information to and from the cortex. This nucleus acts as a relay, not only for the motor information that is processed in the basal ganglia but also for information of an emotional type, whose main centre is the nucleus accumbens. It is also strongly linked with the aspects that determine the mechanisms governing addiction to certain drugs.

DEVELOPMENT

We conduct a detailed analysis of the main findings from studies of the role played by the PPN in the physiopathology of Parkinsonism, namely the study of metabolic activity, immunohistochemical studies with different tracers, electrophysiological studies that have confirmed the immunohistochemical observations, as well as deep electrical stimulation carried out in non human primates. Furthermore, we also examine the part played by this structure in the processing of emotional information associated with different learning tasks.

CONCLUSIONS

Overall, the authors grant the PPN a privileged position in the physiopathology of the axial disorders related to Parkinson s disease; its most important afference, stemming from the subthalamic nucleus, appears to play a key role in the understanding of the part played by the PPN in Parkinsonism.

[Effects of simultaneous transplant of foetal mesencephalic cells in the striatum and the subthalamic nucleus of hemiparkinsonian rats]

INTRODUCTION

The main strategy followed in neural transplants as a method of treatment for Parkinson s disease, both experimental and clinical, has been to introduce foetal mesencephalic cells into the target area: the striatum. However, when the dopaminergic cells in the substantia nigra degenerate, not only is the dopaminergic innervation of the striatum affected but also other nuclei: globus pallidus, substantia nigra, substantia nigra pars reticulata and subthalamic nucleus. A series of data from pharmacological and physiological studies offer strong evidence that the dopamine released in these nuclei may play an important role in regulating the output nuclei of the basal ganglia.

AIM

To evaluate the effect of transplanting foetal mesencephalic cells on the behaviour of 6 OH DA rats when introduced into the striatum and the subthalamic nucleus.

MATERIALS AND METHODS

6 OH DA was used to induce lesions in the substantia nigra of rats, which were divided into several experimental groups. The rotating activity induced by D amphetamine (5 mg/kg, intraperitoneally) and apomorphine (0.05 mg/kg, subcutaneously) was evaluated before and three months after the transplant in all the experimental groups, except in the control group of healthy rats. The hemiparkinsonian rats received a total of 350,000 foetal ventral mesencephalic cells, which were implanted within small deposits in the striatum (8) and in the subthalamic nucleus (4).

RESULTS AND CONCLUSIONS

Rotation induced by both drugs was significantly lower (p= 0.05) in animals that had had dopaminergic cells transplanted into the striatum body. No significant improvement in this behaviour was to be found when transplants were limited to just the subthalamus or, simultaneously, also to the striatum. A significant increase in rotating behaviour induced by apomorphine was observed in the group which received a transplant in just the subthalamus.

[Microdialysis cerebral. Main application of this technique]

INTRODUCTION

Microdialysis cerebral technique has been widely employed in order to study the neurotransmitter release.

DEVELOPMENT

This technique present numerous advantages such as: allow to work with sample in vivo from animals freely moving, by means of microdialysis can be infused simultaneously different drugs in different points implanted probes in several coordinates; also allow carry out pharmacokinetics studies that show correlation with behavior patter as well as to study metabolic changes, which is not possible when this determination are carry out in tissue, in post mortem stadio.

CONCLUSIONS

In the present work is carry out a review about the main results obtaining in the sensitization and abstinence to several drug study and approach to biochemical characteristics to Parkinson s disease (PD) by means of microdialysis technique. In relation to sensibilization studies, the temporal changes in different behavior pattern that modify after amphetamine administration have been studied. Microdialysis study allowed correlationate dopamine concentration with behavior pattern above mentioned. In relation with PD, dopamine concentration after systemic and central (intracerebral) administration of levodopa and another dopaminergic drugs have been studied in different nucleus of basal ganglia as well as its respectively behavior correlates.