Interactions between Angiotensin Type-1 Antagonists, Statins, and ROCK Inhibitors in a Rat Model of L-DOPA-Induced Dyskinesia

Statins have been proposed for L-DOPA-induced dyskinesia (LID) treatment. Statin anti-dyskinetic effects were related to the inhibition of the Ras-ERK pathway. However, the mechanisms responsible for the anti-LID effect are unclear. Changes in cholesterol homeostasis and oxidative stress- and inflammation-related mechanisms such as angiotensin II and Rho-kinase (ROCK) inhibition may be involved. The nigra and striatum of dyskinetic rats showed increased levels of cholesterol, ROCK, and the inflammatory marker IL-1β, which were reduced by the angiotensin type-1 receptor (AT1) antagonist candesartan, simvastatin, and the ROCK inhibitor fasudil. As observed for LID, angiotensin II-induced, via AT1, increased levels of cholesterol and ROCK in the rat nigra and striatum. In cultured dopaminergic neurons, angiotensin II increased cholesterol biosynthesis and cholesterol efflux without changes in cholesterol uptake. In astrocytes, angiotensin induced an increase in cholesterol uptake, decrease in biosynthesis, and no change in cholesterol efflux, suggesting a neuronal accumulation of cholesterol that is reduced via transfer to astrocytes. Our data suggest mutual interactions between angiotensin/AT1, cholesterol, and ROCK pathways in LID, which are attenuated by the corresponding inhibitors. Interestingly, these three drugs have also been suggested as neuroprotective treatments against Parkinson's disease. Therefore, they may reduce dyskinesia and the progression of the disease using common mechanisms.

The interplay between α7 nicotinic acetylcholine receptors, pannexin-1 channels and P2X7 receptors elicit exocytosis in chromaffin cells

Pannexin-1 (Panx1) forms plasma membrane channels that allow the exchange of small molecules between the intracellular and extracellular compartments, and are involved in diverse physiological and pathological responses in the nervous system. However, the signaling mechanisms that induce their opening still remain elusive. Here, we propose a new mechanism for Panx1 channel activation through a functional crosstalk with the highly Ca²⁺ permeable α7 nicotinic acetylcholine receptor (nAChR). Consistent with this hypothesis, we found that activation of α7 nAChRs induces Panx1-mediated dye uptake and ATP release in the neuroblastoma cell line SH-SY5Y-α7. Using membrane permeant Ca²⁺ chelators, total internal reflection fluorescence microscopy in SH-SY5Y-α7 cells expressing a membrane-tethered GCAMP3, and Src kinase inhibitors, we further demonstrated that Panx1 channel opening depends on Ca²⁺ signals localized in submembrane areas, as well as on Src kinases. In turn, Panx1 channels amplify cytosolic Ca²⁺ signals induced by the activation of α7 nAChRs, by a mechanism that seems to involve ATP release and P2X7 receptor activation, as hydrolysis of extracellular ATP with apyrase or blockage of P2X7 receptors with oxidized ATP significantly reduces the α7 nAChR-Ca²⁺ signal. The physiological relevance of this crosstalk was also demonstrated in neuroendocrine chromaffin cells, wherein Panx1 channels and P2X7 receptors contribute to the exocytotic release of catecholamines triggered by α7 nAChRs, as measured by amperometry. Together these findings point to a functional coupling between α7 nAChRs, Panx1 channels and P2X7 receptors with physiological relevance in neurosecretion.

The F-Actin Binding Protein Cortactin Regulates the Dynamics of the Exocytotic Fusion Pore through its SH3 Domain

Upon cell stimulation, the network of cortical actin filaments is rearranged to facilitate the neurosecretory process. This actin rearrangement includes both disruption of the preexisting actin network and de novo actin polymerization. However, the mechanism by which a Ca²⁺ signal elicits the formation of new actin filaments remains uncertain. Cortactin, an actin-binding protein that promotes actin polymerization in synergy with the nucleation promoting factor N-WASP, could play a key role in this mechanism. We addressed this hypothesis by analyzing de novo actin polymerization and exocytosis in bovine adrenal chromaffin cells expressing different cortactin or N-WASP domains, or cortactin mutants that fail to interact with proline-rich domain (PRD)-containing proteins, including N-WASP, or to be phosphorylated by Ca²⁺-dependent kinases, such as ERK1/2 and Src. Our results show that the activation of nicotinic receptors in chromaffin cells promotes cortactin translocation to the cell cortex, where it colocalizes with actin filaments. We further found that, in association with PRD-containing proteins, cortactin contributes to the Ca²⁺-dependent formation of F-actin, and regulates fusion pore dynamics and the number of exocytotic events induced by activation of nicotinic receptors. However, whereas the actions of cortactin on the fusion pore dynamics seems to depend on the availability of monomeric actin and its phosphorylation by ERK1/2 and Src kinases, cortactin regulates the extent of exocytosis by a mechanism independent of actin polymerization. Together our findings point out a role for cortactin as a critical modulator of actin filament formation and exocytosis in neuroendocrine cells.

Effect of inhibitors of NADPH oxidase complex and mitochondrial ATP-sensitive potassium channels on generation of dopaminergic neurons from neurospheres of mesencephalic precursors

Reactive oxygen species signaling has been suggested to regulate stem cell development. In the present study, we treated neurospheres of rat mesencephalic precursors with inhibitors of the NADPH oxidase complex and mitochondrial ATP-sensitive potassium (mitoKATP) channel blockers during the proliferation and/or the differentiation periods to study the effects on generation of dopaminergic neurons. Treatment with low doses (100 or 250 μM) of the NADPH inhibitor apocynin during the proliferation period increased the generation of dopaminergic neurons. However, higher doses (1 mM) were necessary during the differentiation period to induce the same effect. Treatment with general (glibenclamide) or mitochondrial (5-hydroxydecanoate) KATP channel blockers during the proliferation and differentiation periods increased the number of dopaminergic neurons. Furthermore, neither increased proliferation rate nor apoptosis had a major role in the observed increase in generation of dopaminergic neurons, which suggests that the redox state is able to regulate differentiation of precursors into dopaminergic neurons.

Brain angiotensin enhances dopaminergic cell death via microglial activation and NADPH-derived ROS

Angiotensin II (AII) plays a major role in the progression of inflammation and NADPH-derived oxidative stress (OS) in several tissues. The brain possesses a local angiotensin system, and OS and inflammation are key factors in the progression of Parkinson's disease. In rat mesencephalic cultures, AII increased 6-OHDA-induced dopaminergic (DA) cell death, generation of superoxide in DA neurons and microglial cells, the expression of NADPH-oxidase mRNA, and the number of reactive microglial cells. These effects were blocked by AII type-1 (AT1) antagonists, NADPH inhibitors, or elimination of glial cells. DA degeneration increased angiotensin converting enzyme activity and AII levels. In rats, 6-OHDA-induced dopaminergic cell loss and microglial activation were reduced by treatment with AT1 antagonists. The present data suggest that AII, via AT1 receptors, increases the dopaminergic degeneration process by amplifying the inflammatory response and intraneuronal levels of OS, and that glial cells play a major role in this process.

Effects of GABA and GABA receptor inhibition on differentiation of mesencephalic precursors into dopaminergic neurons in vitro

Neurotransmitters have been shown to control CNS neurogenesis, and GABA-mediated signaling is thought to be involved in the regulation of nearly all key developmental stages. Generation of dopaminergic (DA) neurons from stem/precursor cells for cell therapy in Parkinson's disease has become a major focus of research. However, the possible effects of GABA on generation of DA neurons from proliferating neurospheres of mesencephalic precursors have not been studied. In the present study, GABA(A), and GABA(B) receptors were found to be located in DA cells. Treatment of cultures with GABA did not cause significant changes in generation of DA cells from precursors. However, treatment with the GABA(A) receptor antagonist bicuculline (10(-5) M) led to a significant increase in the number DA cells, and treatment with the GABA(B) receptor antagonist CGP 55845 (10(-5) M) to a significant decrease. Simultaneous treatment with bicuculline and CGP 55845 did not induce significant changes. Apoptotic cell death studies and bromodeoxyuridine immunohistochemistry indicated that the aforementioned differences in generation of DA neurons are not due to changes in survival or proliferation of DA cells, but rather to increased or decreased differentiation of mesencephalic precursors towards the DA phenotype. The results suggest that these effects are exerted via GABA receptors located on DA precursors, and are not an indirect consequence of effects on the serotonergic or glial cell population. Administration of GABA(A) receptor antagonists in the differentiation medium may help to obtain higher rates of DA neurons for potential use in cell therapy for Parkinson's disease.

Mechanism of 6-hydroxydopamine neurotoxicity: the role of NADPH oxidase and microglial activation in 6-hydroxydopamine-induced degeneration of dopaminergic neurons

Cell death induced by 6-hydroxydopamine (6-OHDA) is thought to be caused by reactive oxygen species (ROS) derived from 6-OHDA autooxidation and by a possible direct effect of 6-OHDA on the mitochondrial respiratory chain. However, the process has not been totally clarified. In rat primary mesencephalic cultures, we observed a significant increase in dopaminergic (DA) cell loss 24 h after administration of 6-OHDA (40 micromol/L) and a significant increase in NADPH subunit expression, microglial activation and superoxide anion/superoxide-derived ROS in DA cells that were decreased by the NADPH inhibitor apocynin. Low doses of 6-OHDA (10 micromol/L) did not induce a significant loss of DA cells or a significant increase in NADPH subunit expression, microglial activation or superoxide-derived ROS. However, treatment with the NADPH complex activator angiotensin II caused a significant increase in all the latter. Forty-eight hours after intrastriatal 6-OHDA injection in rats, there was still no loss of DA neurons although there was an increase in NADPH subunit expression and NADPH oxidase activity. The results suggest that in addition to the autooxidation-derived ROS and the inhibition of the mitochondrial respiratory chain, early microglial activation and NADPH oxidase-derived ROS act synergistically with 6-OHDA and constitute a relevant and early component of the 6-OHDA-induced cell death.

Serotonin decreases generation of dopaminergic neurons from mesencephalic precursors via serotonin type 7 and type 4 receptors

Inductive signals mediating the differentiation of neural precursors into serotonergic (5-HT) or dopaminergic neurons have not been clarified. We have recently shown that in cell aggregates obtained from rat mesencephalic precursors, reduction of serotonin levels induces a marked increase in generation of dopaminergic neurons. In the present study we treated rat neurospheres with antagonists of the main subtypes of 5-HT receptors, 5-HT transport inhibitors, or 5-HT receptor agonists, and studied the effects on generation of dopaminergic neurons. Cultures treated with Methiothepin (5-HT(1,2,5,6,7) receptor antagonist), the 5-HT(4) receptor antagonist GR113808;67:00-.or the 5-HT(7) receptor antagonist SB 269970 showed a significant increase in generation of dopaminergic cells. Treatment with the 5-HT(1B/1D) antagonist GR 127935, the 5-HT(2) antagonist Ritanserin, the 5-HT transporter inhibitor Fluoxetine, the dopamine and norepinephrine transport inhibitor GBR 12935, or with both inhibitors together, or 5-HT(4) or 5-HT(7) receptor agonists induced significant decreases in generation of dopaminergic cells. Cultures treated with WAY100635 (5-HT(1A) receptor antagonist), the 5-HT(3) receptor antagonist Ondasetron, or the 5-HT(6) receptor antagonist SB 258585 did not show any significant changes. Therefore, 5-HT(4) and 5-HT(7) receptors are involved in the observed serotonin-induced decrease in generation of dopaminergic neurons from proliferating neurospheres of mesencephalic precursors. 5-HT(4) and 5-HT(7) receptors were found in astrocytes and serotonergic cells using double immunolabeling and laser confocal microscopy, and the glial receptors appeared to play a major role.

Expanded mesencephalic precursors develop into grafts of densely packed dopaminergic neurons that reinnervate the surrounding striatum and induce functional responses in the striatal neurons

The search for alternative sources of dopaminergic cells, other than primary fetal tissue for transplantation in Parkinson's disease has become a major focus of research. Different methodological approaches have led to generation in vitro of cells expressing DA-cell markers, although these cells are frequently unable to survive for a long time in vivo after transplantation and/or induce functional effects in the host brain. In the present study, we grafted cell aggregates treated with antibodies against fibroblast growth factor 4 into dopaminergic-denervated striata in rats. Furthermore, we grafted cell suspensions from primary mesencephalic fetal tissue. Grafts from expanded precursors were able to survive (at least 3 months postgrafting) and most decreased the lesion-induced ipsiversive rotation. In addition, immunolabeling for tyrosine hydroxylase and/or Fos showed that the grafts reinnervated the surrounding striatal tissue with dopaminergic terminals, and induced the expression of Fos in the striatal neurons of the reinnervated area after administration of amphetamine to the host rat. The number of dopaminergic cells in grafts from expanded precursors inducing rotational recovery was usually lower (1,226+/-314) than that in grafts from primary fetal tissue (1,671+/-122), but they were more densely packed in grafts that were of smaller volume and did not have the characteristic central nondopaminergic area observed in grafts from primary fetal tissue. The results suggest that long-term survival and functional integration into the DA-denervated striatum can be achieved with grafts of expanded mesencephalic precursors.

Angiotensin II increases differentiation of dopaminergic neurons from mesencephalic precursors via angiotensin type 2 receptors

In addition to the well-known actions of the humoral renin-angiotensin system, all components of this system are present in many tissues, including the brain, and may play a major role in brain development and differentiation. We investigated the possible effects of angiotensin II on the generation of dopaminergic phenotype neurons from proliferating neurospheres of mesencephalic precursors. We observed immunoreactivity for both angiotensin type 1 and type 2 (AT(1) and AT(2)) receptors in the cell aggregates. Double immunolabeling studies revealed that both receptor types are located in neurons and astrocytes. Interestingly, neurons with a dopaminergic phenotype (i.e. tyrosine hydroxylase activity) showed double labeling for AT(1) and AT(2) receptors although the labeling for AT(2) was more intense. Treatment of the neurospheres with angiotensin II (100 nm) during the differentiation period induced a marked increase (about 400%) in the generation of dopaminergic neurons. This was not affected by treatment with the AT(1) antagonist ZD 7155 but was blocked by treatment with the AT(2) antagonist PD 123319. This suggests that AT(2) receptors mediate the stimulatory effect of angiotensin II on the generation of dopaminergic neurons. Apoptotic cell death studies and bromodeoxyuridine immunohistochemistry indicated that the increase in generation of dopaminergic neurons is not due to increased survival or proliferation of dopaminergic cells during treatment with angiotensin and suggested that angiotensin induces increased differentiation of mesencephalic precursors towards the dopaminergic phenotype. Manipulation of the renin-angiotensin system may be useful for increasing production of dopaminergic neurons for transplantation in Parkinson's disease.

Interaction between the noradrenergic and serotonergic systems in locomotor hyperactivity and striatal expression of Fos induced by amphetamine in rats

It is classically considered that Amphetamine acts by increasing extracellular dopamine levels. However, some data suggest a relevant role of other neurochemical systems. The striatum is of particular interest to the study of this question. We have investigated the involvement of the noradrenergic and serotonergic systems and their possible interaction in the striatal responses to Amphetamine using a double behavioral and immunohistochemical approach (i.e., changes in locomotor activity and striatal expression of Fos). In normal rats, Amphetamine induced locomotor hyperactivity and striatal expression of Fos. Pretreatment with the alpha1-adrenergic-receptor antagonist Prazosin or lesion of the serotonergic system significantly reduced the locomotor hyperactivity and striatal Fos expression induced by Amphetamine. Administration of Prazosin to rats with serotonergic denervation did not produce any further reduction in the Amphetamine-induced locomotor hyperactivity or striatal Fos expression compared with that observed in rats with serotonergic denervation only. Amphetamine did not induce a detectable increase in Fos expression in dopamine-denervated striata, and elicited intense rotation towards the dopamine-denervated side. This suggests that striatal dopamine release is essential in the Amphetamine-induced effects on striatal neurons. However, the noradrenergic system plays an important role, and the serotonergic system is necessary for mediating the effects of the Amphetamine-induced noradrenergic stimulation. Concurrent stimulation of dopaminergic and serotonergic receptors appears necessary to regulate Amphetamine-induced responses in the striatal neurons.

Rat brain cholinergic, dopaminergic, noradrenergic and serotonergic neurons express GABAA receptors derived from the alpha3 subunit

In order to study the most abundant GABAA receptor subtypes expressed in cholinergic, dopaminergic, noradrenergic and serotonergic neurons (i.e., in neurons of the so-called "global" projection systems), we employed double-immunocytochemical techniques combining the labeling of GABAA receptor alpha1, alpha2 and alpha3 subunit with markers for these cells. Cholinergic neurons in the striatum, habenula, and pedunculo-pontine nucleus were immunonegative for the alpha1 subunit, and most were also alpha2-immunonegative. However, cholinergic neurons in the striatum, septum and pedunculo-pontine nucleus were alpha3 immunopositive. Dopaminergic neurons in the substantia nigra pars compacta were highly immunopositive for the alpha3, and noradrenergic neurons in the locus coeruleus were immunoreactive for the alpha3 and the alpha2-subunit; although neurons of these areas were negative for alpha1. Similarly, serotonergic neurons in raphe also showed a high level of labeling of alpha3, while there was a lack of immunoreactivity for the alpha1-subunit, and only some individual neurons were positive for the alpha2 subunit. As the presence of different alpha-subunits confers specific physiological and pharmacological properties to GABAA receptors, the abundance of receptors containing the alpha3 subunit (and the scarcity of receptor subtypes including the other alpha-subunits studied) may have important implications for the GABAergic regulation of brain "global" or "diffuse" projection systems.

Long-term cortical atrophy after excitotoxic striatal lesion: effects of intrastriatal fetal-striatum grafts and implications for Huntington disease

It is not currently clear whether the cortical atrophy observed in Huntington disease (HD) is entirely a direct consequence of the disease or at least partially a secondary consequence of striatal atrophy. This is of major importance for evaluating the possible therapeutic value of intrastriatal fetal-striatum grafts in HD. Cresyl violet-stained sections from rats that had received striatal excitotoxic lesions 1 wk or 4 wk previously showed small and statistically nonsignificant decreases in the thickness of cortical layers V and VI, while series from rats lesioned 12 months previously showed marked decreases in the thickness of the whole cortex (approximately 35% decrease), layer V (approximately 45%-50%) and layer VI (approximately 45%-50%), together with marked neuron loss in these layers. In deep layer V and layer VI, Fluoro-Jade staining showed labeled neurons in animals lesioned 1 wk previously, labeled neurons and astrocytes in animals lesioned 4 wk previously, and practically no labeling in animals lesioned 12 months previously. Intracortical injection of Phaseolus vulgaris leucoagglutinin revealed that corticostriatal fibers were practically absent from the lesioned area of striata lesioned 12 months previously. However, rats that received intrastriatal fetal-striatum grafts shortly after the lesion and were killed 12 months later showed a significant reduction in cortical atrophy, and a large number of labeled corticostriatal fibers surrounding and innervating the graft. In addition, a reduction in the number of Fluoro-Jade-labeled cells in the cortex was already apparent at 3 wk post-grafting. Regardless of whether HD has a primary effect on the cortex, the present results suggest that the striatal degeneration caused by HD contributes markedly to the cortical atrophy, and that intrastriatal grafts may ameliorate this secondary component of the cortical degeneration.

Mechanisms of the effects of exogenous levodopa on the dopamine-denervated striatum

The efficacy of exogenous levodopa (L-DOPA) is attributed to its conversion to dopamine by the enzyme aromatic L-amino-acid decarboxylase in striatal dopaminergic terminals. However, there is controversy about the mechanisms underlying the therapeutic and adverse effects of L-DOPA after almost all striatal dopaminergic afferents have disappeared (i.e. in the later stages of Parkinson's disease). After administration of 30mg/kg or 100mg/kg of L-DOPA, rats subjected to unilateral dopaminergic denervation showed intense contraversive rotation and a high density of Fos-immunoreactive nuclei throughout the denervated striatum, with no significant induction of Fos in the intact striatum. Injection of the central aromatic L-amino-acid decarboxylase inhibitor NSD-1015 30min before and 15min after the injection of L-DOPA suppressed the rotational behavior and the striatal induction of Fos. Comparison of results obtained in rats subjected to unilateral and bilateral dopaminergic denervation indicated that the presence of contralateral dopaminergic innervation does not significantly modulate the effects of L-DOPA on the denervated striatum. Serotonergic denervation led to slight and statistically non-significant decrease in the rotational behavior and Fos expression induced by high doses of L-DOPA (100mg/kg) in the dopamine-denervated striatum, but totally suppressed the rotational behavior and Fos expression induced by low doses of L-DOPA (30mg/kg). The present data indicate that the major effects observed after administration of exogenous L-DOPA are not due to a direct action of L-DOPA on dopamine receptors, or to extrastriatal release of dopamine, but to conversion of L-DOPA to dopamine by serotonergic terminals and probably some intrastriatal cells. Given that serotonergic neurons appear to play an important role in the action of L-DOPA in the later stages of Parkinson's disease, strategies targeting the serotonergic system should be considered for the treatment of Parkinson's disease and for combating undesirable side effects of L-DOPA therapy.

GABAA receptor subunit expression in intrastriatal ventral mesencephalic transplants

To compare the expression of GABAA receptor subunits in the normal substantia nigra and in fetal mesencephalic neurons ectopically transplanted into the dopamine-depleted striatum, we have employed single and double immunocytochemical approaches using tyrosine hydroxylase (TH) and alpha 1, alpha 2, alpha 3, and beta 2/3 GABAA receptor subunit specific antibodies. In the substantia nigra, alpha 1 and beta 2/3 GABAA receptor subunits were labeled in processes in the pars compacta (SNc) and, more intensely, in both somata and processes in the pars reticulata (SNr). There was no clear TH and alpha 1 or beta 2/3 colocalization, with the exception of some TH-immunoreactive (-ir) neurons that showed a weak immunoreactivity for beta 2/3. Sections immunolabeled for alpha 2 showed a faint diffuse labeling for this subunit both in the SNr and in the SNc. Scattered somata were immunopositive for alpha 2, and some of them were also TH-ir. The labeling for alpha 3 and TH showed that TH-positive neurons expressed intense alpha 3 immunoreactivity, although some TH-negative somata in the SNr expressed weak alpha 3 immunoreactivity. In the transplants, double immunostaining procedures showed that the labeling for alpha 1 or beta 2/3 appeared particularly concentrated in patches of intensely immunoreactive neuronal processes that surrounded TH-ir cells, but these processes were not TH-ir. In the case of alpha 2, diffuse immunostaining was observed all over the graft, with some scattered positive somata. Only a few of them were also TH positive. Sections immunoreacted for alpha 3 and TH revealed that TH-ir neurons expressed intense alpha 3 immunoreactivity, and that only a few TH-negative neurons were weakly positive for alpha 3. These results show that mesencephalic tissue ectopically grafted into the striatum develops a pattern of GABAA receptor expression similar to that normally expressed in situ, and particularly that the grafted dopaminergic neurons express similar GABAA receptors, including the alpha 3 subunit. This might be due to the similarity of GABAergic afferents to these neurons in the SNc and the graft, or that at the time of transplantation this expression had already been determined.

Fenfluramine-induced increase in preproenkephalin mRNA levels in the striatum: interaction between the serotonergic, glutamatergic, and dopaminergic systems

Fenfluramine (FE) is a halogenated amphetamine derivative that has been used in the treatment of obesity. It has been suggested that the effects of FE on the striatum are mediated by serotonergic mechanisms. However, several major afferent systems may be involved, and administration of FE may be useful to study interactions between these systems. In this work, the effects of FE on striatopallidal neurons and the possible involvement of the major striatal afferent systems were studied in rats by determination of FE-induced changes in striatal levels of preproenkephalin (PPE) mRNA using in situ hybridization. Injection of FE induced a significant increase (60%) in striatal levels of PPE mRNA. This increase was blocked by pretreatment with the D(1) dopamine receptor antagonist SCH-23390 or with the NMDA glutamate receptor antagonist MK-801, or by lesion of the serotonergic system with 5,7-dihydroxytryptamine or p-chlorophenylalanine. In 6-hydroxydopamine lesioned rats, the lesion-induced increase in PPE mRNA levels was not affected by injection of FE, but was reduced by simultaneous serotonergic deafferentation. The results suggest that the serotonergic, glutamatergic, and dopaminergic system interact to increase striatal PPE mRNA levels after FE administration.

Recovery after nigral grafting in 6-hydroxydopamine lesioned rats is due to graft function and not significantly influenced by the remaining ipsilateral or contralateral host dopaminergic system

The aim of this study was to evaluate whether the recovery observed after grafting of fetal nigral cells in 6-hydroxydopamine lesioned rats is due to the graft itself, and whether the participation of the remaining host dopaminergic system is necessary. The effects of unilateral 6-hydroxydopamine lesion on rotational behavior were not significantly affected by sham grafting or by sham grafting plus repeat ipsilateral lesion, but were suppressed by nigral grafting, and by contralateral lesion. Immunohistochemical and in situ hybridization study of right striata of rats subjected to right-side lesion then right-side sham-grafting, and of right and left striata from rats subjected to right-side lesion then right-side sham-grafting then repeat right-side lesion then left-side lesion, revealed (a) no significant amphetamine-induced Fos activation, (b) marked increases in preproenkephalin mRNA levels, and (c) decreases in preprotachykinin levels, with no significant differences in any of these variables among these three types of striata. After nigral grafting, however, intense Fos expression was observed in the striatum, and preproenkephalin and preproenkephalin mRNA levels returned to normal. This recovery was maintained after subsequent repeat ipsilateral 6-hydroxydopamine lesion followed by contralateral lesion. The results demonstrate that, after dopaminergic denervation, the nigral graft itself is able to induce recovery in the assessed parameters, and that these effects of grafting into striata with maximal unilateral 6-hydroxydopamine lesion are due to graft function, and are not significantly influenced by the remaining ipsilateral or contralateral host dopaminergic system. Additionally, it is interesting to note that bilateral denervation led to changes in striatal preproenkephalin and preproenkephalin mRNA levels similar to those observed after unilateral lesion.

Striatal dopaminergic afferents concentrate in GDNF-positive patches during development and in developing intrastriatal striatal grafts

Glial cell line-derived neurotrophic factor (GDNF) has potent trophic action on fetal dopaminergic neurons. We have used a double immunocytochemical approach with antibodies that recognize GDNF and tyroxine hydroxylase (TH) or the phosphoprotein DARPP-32, to study the developmental pattern of their interactions in the rat striatum and in intrastriatal striatal transplants. Postnatally, at one day and also at 1 week, GDNF showed a patchy distribution in the striatum, together with a high level of expression in the lateral striatal border, similar to that observed for the striatal marker DARPP-32 and also for TH. In the adult striatum, there was diffuse, weak immunopositivity for GDNF, together with widespread expression of DARPP-32-positive neurons and TH-immunoreactive (TH-ir) fibers. In 1-week-old intrastriatal striatal transplants, there were some GDNF immunopositive patches within the grafts and although there was not an abundance of TH-positive fibers, the ones that were seen were located in GDNF-positive areas. This was clearly evident in 2-week-old transplants, where TH-ir fibers appeared selectively concentrated in GDNF-positive patches. This pattern was repeated in 3-week-old grafts. In co-transplants of mesencephalic and striatal fetal tissue (in a proportion of 1:4), TH-ir somata were located mainly at the borders of areas that were more strongly immunostained for GDNF, and TH-ir fibers were also abundant in these areas and were found in smaller numbers in regions that were weakly positive for GDNF. These results demonstrate that GDNF-ir is coincident with that for TH and DARPP-32, and suggest that GDNF release by fetal striatal neurons both in normal development and in developing striatal grafts may have not only a trophic but also a tropic influence on TH-ir fibers and may be one of the factors that regulate dopaminergic innervation of the striatum.

The overall rod performance test in the MPTP-treated-mouse model of Parkinsonism

We investigated the usefulness of the Overall Rotarod Performance (ORP) test for evaluating overall locomotory ability in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-injected-mouse model of Parkinson's disease (PD). For this procedure, the mice are pretrained on the rotarod and then tested at a series of increasing speeds, recording the time that the animal remains on the rod at each speed; the overall rod performance (ORP) of each animal is then calculated as the area under the curve in a plot of time-on-the-rod against rotation speed. At 15-day intervals, C57BL/6 mice were injected (or sham-injected) with MPTP, with ORP testing 7-10 days after each injection. After the fourth injection (day 45), mice in the treated group showed clearly lower ORP than mice in the control group (70-90% reduction in ORP), and were thus considered effectively lesioned. Subsequently, we investigated the short-term effects of apomorphine and L-DOPA on ORP in MPTP-treated mice. Apomorphine (at 0.5 or 2.5 mg/kg) had no significant effect, while L-DOPA (at 80 but not at 40 mg/kg) caused almost complete short-term recovery of pretreatment ORP. By about 100 days after the last MPTP injection, MPTP-treated mice showed partial long-term recovery of ORP; at this stage the mice were killed for tyrosine hydroxylase (TH) immunohistochemistry studies. TH immunoreactivity in the striatum showed a strong positive correlation with ORP as tested on day 100. We conclude that the ORP test is useful for evaluating motor deficit in MPTP-treated mice, and the effects of subsequent treatments.

Mature intrastriatal striatal grafts revert the changes in the expression of pallidal and thalamic alpha 1, alpha 2 and beta 2/3 GABAA receptor subunit induced by ibotenic acid lesions in the rat striatum

A between-side comparison of GABAA receptor subunit expression levels in the globus pallidus and anterior-pole motor thalamic nuclei of rats with an ibotenate lesion of the striatum, and rats receiving a fetal striatal graft in the lesioned area was made by using immunocytochemistry with subunit-specific antibodies, at different times post-lesion or different times post-grafting. At 10 days post-lesion, there was already an increase in the labeling of the alpha 1- and beta 2/3-subunits in the globus pallidus, entopeduncular nucleus and ventrolateral nucleus ipsilateral to the lesion when compared with the contralateral side, while there were no significant changes at the level of the ventromedial nucleus. Labeling of the alpha 2-subunit showed a clear increase in the entopeduncular nucleus compared with the contralateral side at 10 days post-lesion. Similar changes were also observed for the different subunits studied at 30 and 120 days after lesioning. Rats with 20-day old transplants of fetal striatal neurons that were implanted in the ibotenate lesioned striatum at 10 days post-lesioning, continued to show changes in the expression of GABAA receptor subunits, albeit at a lower level than those of ibotenate lesioned rats at similar age post-lesion. However, when examining rats with 70-day old transplants, the ibotenate-lesion induced between-side changes were almost completely compensated. These findings suggest a correlation between the maturation of the grafts and their capability to function in reestablishing neuronal circuits as shown by the reduction of changes in GABAergic transmission induced by ibotenate lesions, as indicated by the reversal of changes in GABAA receptor subunit in several areas of the basal ganglia circuit.

The corticostriatal system mediates the "paradoxical" contraversive rotation but not the striatal hyperexpression of Fos induced by amphetamine early after 6-hydroxydopamine lesion of the nigrostriatal pathway

In rats with unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal pathway, amphetamine produces ipsiversive rotational behavior and activation of Fos in the intact striatum, but practically no activation of Fos in the denervated striatum. However, a seemingly paradoxical contraversive rotation, accompanied by intense striatal Fos activation in the lesioned striatum, has been observed during the first few days postlesion. In the present work, behavioral tests and immunohistochemistry for Fos protein and tyrosine hydroxylase (TH) were combined to study striatal changes 36 h after 6-OHDA lesion and particularly the possible involvement of glutamatergic corticostriatal afferents. Injection of amphetamine (0.5 mg/kg or 5 mg/kg) induced contraversive rotation and strong and evenly distributed Fos expression in the lesioned striatum; in the contralateral striatum, however, Fos density was lower than in nonlesioned rats. Pretreatment with the N-methyl-D-aspartate (NMDA) glutamate receptor antagonist MK-801 (either 0.5 mg/kg or 5 mg/kg) did not significantly affect the hyperexpression of Fos in the lesioned striatum, but suppressed the contraversive rotation. Similarly, rats that were subjected to corticostriatal deafferentation (confirmed by sensory neglect tests) and 6-OHDA lesion (1 week or 3 weeks later) showed no significant reduction in the striatal Fos hyperexpression induced by amphetamine (0.5 mg/kg or 5 mg/kg) and no significant rotational asymmetry. In conclusion, the present results indicate that glutamatergic corticostriatal afferents are essential for the contraversive rotational behavior but not the striatal hyperexpression of Fos observed in response to amphetamine early after 6-OHDA lesion, and suggest that intense dopaminergic stimulation of striatal neurons is sufficient for induction of Fos, but that concurrent glutamatergic stimulation is necessary for the motor response.

Sprouting of the serotonergic afferents into striatum after selective lesion of the dopaminergic system by MPTP in adult mice

Neonatal destruction of the nigrostrial dopaminergic (DA) system with 6-hydroxydopamine leads to serotonergic (5-HT) hyperinnervation of the striatum. However, it is not clear whether this occurs in adult animals. We investigated whether serotonergic sprouting occurs in adult mice subjected to bilateral lesion of the DA system by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The effects of the lesion were evaluated using a new rotarod test and immunohistochemistry. One hundred days after the last MPTP lesion, there was a clear bilateral serotonergic hyperinnervation throughout the striatum. Additionally, those mice showing the highest reductions in striatal tyrosine hydroxylase (TH) immunoreactivity and in rotarod performance showed the highest density of serotonergic innervation (116% increase). The functional consequences of this process in Parkinson's disease and secondary parkinsonism remain to be clarified.

Interaction between the serotonergic, dopaminergic, and glutamatergic systems in fenfluramine-induced Fos expression in striatal neurons

Fenfluramine (FE) is a halogenated amphetamine derivative used in the treatment of obesity and thought to induce serotonin (5-HT) release from nerve terminals and to reduce re-uptake. However, other pathways may also be involved. In this work, the effects of FE on the major striatal afferent systems, and the possible interactions of these systems in FE-induced striatal expression of Fos, were studied by lesion of the serotonergic and/or dopaminergic system and administration of NMDA glutamate (MK-801) or D1 dopamine (SCH-23390) receptor antagonists. Both the D1 and NMDA receptor antagonists suppressed Fos expression in response to FE almost entirely. FE-induced Fos expression was also dramatically reduced 24 h after 6-hydroxydopamine (6-OHDA) lesion of the dopaminergic system. However, the reduction was not so marked after chronic 6-OHDA lesion, probably due to compensatory changes. Chronic (5,7-dihydroxytryptamine injection, 4 weeks before) or acute (p-chlorophenylalanine injection) lesion of the serotonergic system led to a marked reduction in Fos expression in response to FE (decrease of about 50%). After simultaneous chronic lesion of both serotonergic and dopaminergic systems, a considerable number of Fos-positive nuclei were still observed (decrease of about 70% in the dorsal and dorsomedial regions). The FE-induced expression of Fos was almost totally suppressed (decrease of about 95% in the dorsal and dorsomedial regions) after simultaneous acute lesion. Our results indicate that FE-induced striatal expression of Fos is due in large measure to DA release and dopaminergic stimulation of D1 receptors. However, concurrent stimulation of NMDA glutamate receptors also appears to be essential, and 5-HT release (although not indispensable) doubles striatal Fos expression.

An automated rotarod method for quantitative drug-free evaluation of overall motor deficits in rat models of parkinsonism

A variety of tests have been proposed for evaluation of motor deficits in rat models of hemiparkinsonism. The most widely used test, the "rotational behaviour" test, is based upon motor asymmetry induced by drug administration, leading to problems of sensitization, conditioning and priming. In addition, lesion-induced rotational behaviour is sometimes overcompensated by treatments (grafts) while other deficits are unaffected. However, rotational behaviour is reproducible and easy to quantify. On the contrary, most drug-free tests have proved of limited applicability because of subjective scaling, excessive interaction between the experimenter and animals, motivational effects, excessively complex tasks, etc., making it difficult to compare results from different laboratories. In this paper, we present a rotarod based method for automated drug-free evaluation of overall motor deficits in the rat model of hemiparkinsonism, and for identifying treatment-induced changes. Animals are pre-trained on the rotarod and then tested at a series of increasing rod speeds; from this set of values a unique score for each animal is computed (the overall rotarod performance, ORP) summarizing its performance at different speeds. This value is easy to compute and greatly simplifies statistical comparisons. Major advantages of the test are: (i) it does not require drugs, but is nevertheless highly objective, reproducible and easy to quantify; and (ii) falling of animals from rotating rod seems to depend on a combination of lesion-induced deficits which become more evident when rats are forced to move at faster speeds. Since the test is not based exclusively on motor asymmetry, it may also be useful for characterization of bilaterally lesioned animals, for which drug-induced rotational behaviour tests cannot be used.

GABA(A) receptor subunit expression in intrastriatal striatal grafts comparison between normal developing striatum and developing striatal grafts

Expression of the alpha1, alpha2 and beta2/3 GABA(A) receptor subunits in maturing cell-suspension striatal grafts and in normal developing striatum was studied by immunocytochemistry. During normal postnatal development, the alpha1 subunit was present in the striatum only at very low density, while the alpha2 and beta2/3 subunits were present with a patchy distribution, in some patches at high density. Double-staining techniques indicated that DARPP-32 (a marker of striatal projection neurons) was not colocalized with alpha1, but was present in some beta2/3-positive areas and all alpha2-positive areas. In striatal grafts, alpha1 immunoreactivity was first detected 2 weeks post-grafting (p.g.), and by 3-10 weeks p.g. the pattern was similar to that observed in mature grafts (1 year p.g.), in which alpha1-immunopositive patches surrounding DARPP-32-positive (i.e. striatum-like) areas are observed. Alpha2 and beta2/3 immunoreactivity was observed within the first week p.g., and by 3-10 weeks p.g. was similar to that observed in mature grafts (i.e. immunoreactivity throughout the graft but with patches of different intensity). During graft maturation there was a marked decline in alpha2 immunoreactivity in DARPP-32-negative areas, as is observed during normal development of the globus pallidus and ventral pallidum. Interestingly, alpha1- and beta2/3-positive fibers (perhaps mostly dendrites) entered DARPP-32-positive patches from DARPP-32-negative areas. This study indicates that the time course of expression of GABA(A) receptor subunits in grafted striatal neurons, closely matches that of morphological maturation of the transplant, that of the development of functional synaptic activity and that of GABA(A) receptor subunit immunoreactivity in normal developing striatum. Our results also suggest that there are significant interactions between DARPP-32-positive and DARPP-32-negative areas with respect to the expression of GABA(A) receptors, and support the suggestion that miniature 'striatopallidal systems' may develop within grafts; such interactions may be important for the functional integration of striatal grafts with the host brain.

Effects of lesions of the nigrostriatal pathway and of nigral grafts on striatal serotonergic innervation in adult rats

Neonatal destruction of the nigrostriatal dopaminergic system leads to serotonergic hyperinnervation of the striatum. However, it is not clear whether this occurs in adult animals. We investigated whether serotonergic sprouting occurs in adult animals, and also studied the effects of prior or subsequent implantation of dopamine-rich intrastriatal grafts. One group of adult rats received maximal 6-hydroxydopamine lesions. Other rats received maximal lesions and intrastriatal grafts 2 months later, or vice versa. The lesioned non-grafted rats showed clear serotonergic hyperinnervation throughout the striatum ipsilateral to the lesion. Intrastriatal grafts did not prevent or revert this serotonergic hyperinnervation, and were themselves densely innervated by serotonergic fibers. Serotonergic neurons usually present in the grafted cell suspension also contributed to the serotonergic innervation of the graft and the surrounding striatum.

Time course of striatal, pallidal and thalamic alpha 1, alpha 2 and beta 2/3 GABAA receptor subunit changes induced by unilateral 6-OHDA lesion of the nigrostriatal pathway

Immunocytochemical techniques were used to investigate the distribution and abundance of GABAA receptor subunits (alpha 1, alpha 2 and beta 2/3) in the brains of unilaterally 6-OHDA-lesioned rats. Three and 7 days after lesion, the alpha 2-subunit was significantly more abundant in the lesion-ipsilateral striatum than in the lesion-contralateral striatum; by 4 weeks after lesion, however, no significant between-side differences were observed. Three and 7 days after lesion, the alpha 1-subunit was significantly less abundant in the lesion-ipsilateral globus pallidus than in the lesion-contralateral side; again, this difference disappeared within 4 weeks of lesion. Similarly, alpha 1 was initially less abundant in several relay thalamic nuclei on the lesioned side while alpha 2 was initially more abundant in intralaminar thalamic nuclei on the lesioned side. There were no significant between-side changes for the beta 2/3-subunits. Comparison of non-lesioned and 6-OHDA-lesioned rats revealed significant differences in brain areas which also showed differences on comparison of the lesioned and non-lesioned sides of 6-OHDA-lesioned rats. These results suggest that there is an early adaptation to the lesion, achieved through changes in GABAA receptor abundance. That some of these changes are no longer apparent after 4 weeks is due not only to partial reversion of the changes in the lesioned side but also to compensatory changes in the non-lesioned side.

Treadmill running induces striatal Fos expression via NMDA glutamate and dopamine receptors

Several non-physiological stimuli (i.e. pharmacological or electrical stimuli) have been shown to induce Fos expression in striatal neurons. In this work, striatal Fos (i.e. Fos-like) expression was studied after physiological stimulation, i.e. motor activity (treadmill running at 36 m/min for 20 min). In rats killed 2 h after the treadmill session, Fos expression was observed in the medial region of the rostral and central striatum, and in the dorsal region of the caudal striatum. Fos expression was prevented by pretreatment with the non-competitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist MK-801 (0.1 mg/kg) or the D1 dopamine receptor antagonist SCH-23390 (0.1 mg/kg), but not by pretreatment with the D2 receptor antagonist eticlopride (0.5 mg/kg). Thirty-six hours after 6-hydroxydopamine lesion, a considerable reduction in treadmill-induced Fos expression was observed in both sides; however, Fos expression in the lesioned striatum was higher than in the contralateral intact striatum. Several weeks after unilateral 6-hydroxydopamine lesion of the nigrostriatal system, treadmill-induced Fos expression was significantly, but not totally, reduced in the lesioned striatum. Corticostriatal deafferentation also led to considerable reduction in treadmill-induced Fos expression. The present results indicate that exercise induces striatal Fos expression and that, under physiological stimulation, concurrent activation of D1 and NMDA receptors is necessary for such expression to occur. Reduction of Fos expression is practically absolute after acute blockage of these receptors, but not after lesions, possibly due partially to compensatory changes.

Intrathalamic implants of GABA-releasing polymer matrices reduce motor impairments in rats with excitotoxically lesioned striata

Current models of basal ganglia disorders suggest that the choreoathetosis is the end result of reduced GABAergic inhibition of the motor thalamus. GABA-releasing polymer matrices or control matrices without GABA were implanted either unilaterally or bilaterally in the vicinity of the ventromedial thalamic nucleus of normal rats and of rats with unilateral or bilateral excitotoxic striatal lesions (rat model of Huntington's disease), to study the effects of these GABA-releasing matrices on amphetamine-induced rotational behavior (unilateral implants in unilaterally lesioned rats) and on overnight spontaneous locomotor activity (bilateral implants in bilaterally lesioned rats). Unilateral implants led to a reduction (about 25%) in motor asymmetry; the response was transitory, probably because of the exhaustion of GABA release by the matrix. Some rats showed a more marked and permanent reduction of motor asymmetry, but this was probably due to lesion of the ventromedial nucleus or its thalamocortical projection. Bilateral implants of GABA-releasing matrices (but not control matrices) led to a marked (about 65%) but again transitory reduction in the locomotor hyperactivity induced by bilateral striatal lesion. These results suggest that implantation of a GABA-releasing source may be an effective alternative to intrathalamic fetal-tissue grafts or lesions as an experimental approach to the treatment of hyperkinetic movement disorders.

Previous dopaminergic innervation is not necessary for the development of dopamine supersensitivity in rat striatal neurons

The development of supersensitivity to dopamine by striatal neurons is widely considered to be a response to interruption of dopaminergic synaptic function. However, it is not clear whether pre-existing dopaminergic innervation is in fact necessary for supersensitivity to develop. In this study, rat foetal striatal cells were obtained prior to their innervation by dopaminergic fibres, and grafted into the cortex or thalamus of adult rats. In the absence of dopaminergic innervation, the grafts developed and became organized into striatum-like and non-striatum-like patches. Both in animals with intrathalamic and in animals with intracortical grafts, systemic administration of a low dose of apomorphine (0.25 mg/kg) induced intense fos expression in striatum-like patches not innervated by dopaminergic fibres. These results indicate that pre-existing dopaminergic innervation is not required for the development of supersensitivity, and that dopaminergic innervation is necessary to develop an adequate synergistic interaction between D1 and D2 receptors.

Time course of striatal changes induced by 6-hydroxydopamine lesion of the nigrostriatal pathway, as studied by combined evaluation of rotational behaviour and striatal Fos expression

Changes taking place after unilateral 6-hydroxydopamine lesion of the dopaminergic nigrostriatal system have been studied by performing spontaneous, amphetamine-induced and apomorphine-induced rotational behaviour testing and tyrosine hydroxylase (TH) and Fos protein immunohistochemistry in the same rats. Apomorphine at a low dosage (0.25 mg/kg) induced contraversive rotation and supersensitive striatal Fos expression that were detected 24-48 h post-lesion and gradually increased in magnitude. Twenty-four hours after lesion, both high (5 mg/kg) and low doses (0.5 mg/kg) of D-amphetamine induced contraversive rotation and intense striatal Fos activation on the denervated side; however, only the higher dose induced Fos on the normal side. Two, 3 and 4 days after lesion, 0.5 mg/kg amphetamine induced contraversive rotation, but 5 mg/kg induced transitory contraversive rotation which switched to ipsiversive. In the normal striatum, only high doses of amphetamine induced Fos, but Fos induction in the denervated striatum was similar with both doses: areas showing severely decreased TH immunoreactivity still showed considerable Fos immunoreactivity, and some areas still showing TH immunoreactivity had higher Fos density than in the normal side. Seven and 14 days after lesion the loss of TH immunoreactivity and apomorphine-induced supersensitive Fos expression were more evenly distributed, and amphetamine induced only ipsiversive rotation and a low density of Fos-positive nuclei in the denervated striatum. These results indicate that the severe and progressive loss of dopaminergic terminals is counteracted by an early and rapidly progressing dopamine supersensitivity, together with a higher susceptibility to drug-induced dopamine release. This explains the apparently paradoxical contraversive rotation induced by amphetamine during the first week post lesion. However, experiments involving successive drug injections indicated that only the first amphetamine injection releases dopamine from the lesioned terminals.

Cortical stimulation induces Fos expression in striatal neurons via NMDA glutamate and dopamine receptors

Cortical electrical stimulation has been shown to induce dense and widespread Fos expression throughout the ipsilateral and contralateral striatum. This raises interest for studying the mechanisms underlying the regulation of striatal neuron activity by cortical afferents, and for elucidating the interactions with other systems. However, the receptors mediating cortical-stimulation-induced expression of Fos in striatal neurons have not been identified. This was studied in the work reported here by stimulating the cortex after administration of glutamate or dopamine receptor antagonists, or after 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal dopaminergic system. Pretreatment with the non-competitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist MK-801 led to a marked reduction in the stimulation-induced density of Fos-immunoreactive nuclei in both the medial (about 80% reduction) and lateral (about 50-60% reduction) striatum. Preadministration of the D1-selective dopamine antagonist SCH-23390 alone or in combination with the D2-selective dopamine antagonist eticlopride led to a reduction in the stimulation-induced density of Fos-positive nuclei of about 60-65% in the lateral striatum, but no significant change in the medial region. The effects of 6-OHDA lesion were less pronounced, and the stimulation-induced density of Fos-immunoreactive nuclei decreased by only about 25% in the lateral region. These results indicate that both dopamine and NMDA glutamate receptors are involved in the induction of Fos by cortical stimulation, and support the hypothesis that cortex-dopamine interactions in the lateral striatum may be functionally different from those in the medial striatum.

Intrathalamic striatal grafts survive and affect circling behaviour in adult rats with excitotoxically lesioned striatum

Current models of basal ganglia disorders suggest that choreoathetosis is the end result of reduced GABAergic inhibition of the motor thalamus. Graft-derived release of GABA from intrastriatal striatal grafts has also been reported. In the present work, cell suspension grafts from embryonic day 14-15 rat striatal primordia were implanted close to the ventromedial thalamic nucleus to investigate whether they can develop and survive in this ectopic location, and whether they induce changes in the circling behaviour of the host. The grafts were implanted either in normal rats or in rats whose striatum had been lesioned with ibotenic acid. These grafts were implanted either ipsilateral or contralateral to the lesioned striatum. Additionally, some rats received intrastriatal grafts, and lesioned but non-grafted rats and lesioned rats that had received injections of saline or of cell suspensions from fetal spinal cord in the thalamus were used as control. Four to eight months after transplantation, circling behaviour after amphetamine or apomorphine injection was evaluated. Serial sections were stained with Cresyl Violet and studied immunohistochemically with antibodies against DARPP-32 (dopamine- and adenosine 3',5'-monophosphate-regulated phosphoprotein, as striatal marker), Fos protein, glutamate decarboxylase (67,000 mol. wt), glutamate decarboxylase (65,000 mol. wt) and GABA. Cresyl Violet sections showed that the intrathalamic striatal grafts developed into tissue masses resembling those observed in intrastriatal striatal grafts. DARPP-32 immunohistochemistry revealed that the grafts were composed of DARPP-32 immunoreactive (striatum-like) and DARPP-32-negative patches. The intrathalamic grafts of rats which had received a low dose of apomorphine (0.25 mg/kg) 2 h before perfusion showed clusters of intensely Fos-immunoreactive nuclei throughout the transplant, indicating that these cells had developed dopamine receptors and supersensitivity to dopamine agonists. Double Fos and DARPP-32 immunohistochemistry revealed that the Fos-positive nuclei were located in the striatum-like areas. Finally, the intrathalamic grafts also contained neurons immunoreactive to GABA and glutamate decarboxylase (65,000 and 67,000 mol. wt). Rats that had received intrathalamic grafts contralateral to the lesioned striatum (i.e. contralateral to the lesion-induced turning direction) showed a significant reduction of circling both after amphetamine (78% reduction) or apomorphine (77% reduction) injection. Rats that had received grafts ipsilateral to the lesioned striatum showed a 75% decrease in amphetamine-induced circling, but no significant change in apomorphine-induced circling. No significant drug-induced circling was observed in non-lesioned and grafted rats. Sham grafting (saline) or grafting of weakly GABAergic tissue (fetal spinal cord) had no significant effects on lesion-induced circling behaviour.(ABSTRACT TRUNCATED AT 400 WORDS)

[Evaluation of the acceptability of a formula for children with diarrhea in a marginal community]

Evaluated the acceptability of a nutrition formula consisting of pumpkin-rice chicken and oils; in a marginal community to children between the ages of 7 months to 5 years old when acute diarrhea was present. The acceptability was also evaluated in the mothers, who indicated that they liked food very little. Nevertheless, they admitted that they would give the product to their children. During the period of study 26 cases of diarrhea were reported of the 26 children, 6 children consumed all the food offered, 16 children showed variable acceptance and only 4 children reject the food completely. By age-groups, the acceptability was 75.69% for children between the ages of 7 months to one year. 72.90% acceptability for ages between 13 months to 2 years and 78.28% for ages between 25 months to 5 years old. The total acceptability was 75.66%. All cases presented marked decreased in diarrhea and an increased in the consistency of the feces with the third dose.

Cortical stimulation induces fos expression in intrastriatal striatal grafts

Innervation of intrastriatal grafts of fetal striatal tissue by host corticostriatal projections has been shown in a number of previous studies in rats. In the work reported here, induction of Fos protein in grafted striatal neurons by electrical stimulation of the host frontoparietal cortex has been used as cell-level marker of corticostriatal postsynaptic responses within the striatal grafts. Unilateral cortical stimulation 30 min before sacrifice led to bilateral widespread and intense Fos induction throughout the normal striatum, although the response was somewhat more intense ipsilaterally and in the dorsolateral rostral striatum. In adult rats whose striatum had been lesioned with ibotenic acid 10-12 days prior to implantation of fetal striatal tissue, 3- and 18-month-old striatal grafts showed Fos immunoreactivity in a considerable number of cells after either bilateral, or ipsilateral (approximately 30-40% of the density of Fos-immunoreactive cells in the normal striatum) or contralateral cortical stimulation. Double-Fos and -DARPP-32 immunohistochemistry revealed that the Fos-immunoreactive nuclei were concentrated in the DARPP-32-positive (i.e. striatum-like) patches, which contained approximately 60% of the density of Fos-positive nuclei in the normal striatum after either ipsilateral or bilateral stimulation. However, Fos-immunoreactive nuclei were unevenly distributed within the DARPP-32-positive compartment of the graft, with some clusters of Fos-immunoreactive nuclei at 2-3 x the density observed in the normal striatum and other areas with Fos-immunoreactive nuclei present at lower density or absent. Fos induction was also observed in 4-week-old grafts, indicating that functional corticostriatal synaptic contacts develop rapidly. Striatal grafts implanted either in non-lesioned host striatum or in long-term (18 months) lesioned striatum, similarly showed Fos-positive nuclei after cortical stimulation, indicating that host corticostriatal fibers are equally capable of establishing functional synaptic contacts under these conditions. These results indicate that host corticostriatal fibres not only form an axonal network within the graft but also induce postsynaptic responses which may contribute to the observed graft-induced amelioration of lesion-derived behavioural deficits.

Comparison between normal developing striatum and developing striatal grafts using drug-induced Fos expression and neuron-specific enolase immunohistochemistry

The cell-level functional maturation of cell suspension grafts from embryonic day 14-15 rat striatal primordia implanted unilaterally into ibotenic acid lesioned striata of adult female rats was studied from two days to 10 weeks post-grafting. The functional and morphological characteristics of the grafts were compared with those of adult grafts (one year after implantation), normal adult striata and postnatal developing striata (up to four weeks after birth). Serial sections were stained with Cresyl Violet and investigated immunohistochemically with antibodies against dopamine- and adenosine 3',5'-monophosphate-regulated phosphoprotein (DARPP-32, as a striatal marker), tyrosine hydroxylase (as a marker of dopaminergic fibres), Fos protein (as a cell-level marker of functional dopaminergic host-graft interactions), and neuron-specific enolase (correlated to differentiation and functional maturation of neuronal cells). Selected sections were double-stained for DARPP-32 and either tyrosine hydroxylase, Fos or neuron-specific enolase. The rats used to study dopamine receptor-activated expression of Fos were killed 2 h after administration of either the dopamine-releasing agent D-amphetamine (5 mg/kg intraperitoneally) or the dopamine-receptor agonist apomorphine (0.25 mg/kg subcutaneously, at which dosage it is active only on supersensitive receptors of denervated neurons). In normally developing rats, amphetamine induced Fos expression in both the striatum and globus pallidus by two weeks after birth; by four weeks, the pattern of amphetamine-induced Fos immunoreactivity was similar to that observed in adults. In the globus pallidus of both two- and three-week-old rats, amphetamine induced greater expression of Fos than in adults. Apomorphine did not induce appreciable Fos activation in either the striatum or the globus pallidus at any stage of development. In striatal grafts, amphetamine induced Fos expression from three weeks after implantation onwards, and by five to 10 weeks post-grafting the pattern of Fos immunoreactivity was similar to that observed in adult grafts. However, apomorphine induced a considerable number of Fos-positive nuclei in striatal grafts at three and four weeks after grafting. Neuron-specific enolase immunoreactivity was moderate in normal adult striatum and very high in the adult globus pallidus, and mainly located in neuronal perikarya and processes. Before two weeks of age, most neuron-specific enolase immunoreactivity was observed in internal capsule fascicles and the striatal afferents. Between two and four weeks after birth, neuron-specific enolase immunoreactivity in striatal and globus pallidus neurons gradually increased, while that in afferent fibres decreased to adult levels.(ABSTRACT TRUNCATED AT 400 WORDS)

[Soy and corn flour precooked with microwaves and its use in the preparation of arepas]

Unhusked corn and soy grits were used as raw material, with a particle size ranging between 10 and 20 mesh (ASTM). The results obtained in this study reveal that microwave heating is effective in destroying the antinutritional factors present in soybeans. The trypsin inhibitor activity, in effect, was reduced to a 76% inactivation. The hemagglutinating titer was labile to the heating process, showing values of +8 to +3 for the full-fat soy flour and precooked soy flour, respectively. The quality of soy protein was measured by the protein efficiency ratio (PER) showing values of 2.63 for the precooked soy flour, and 2.46 to 2.21 for the precooked corn:soy blends (70:30 and 50:50). These uncooked blends present values of 1.17 and 1.04. The enriched corn:soy flour had a PER value of 1.60, in comparison to casein (PER = 2.90). The microwave heating improved the digestibility of the soy flour and blends. There were no significant differences (P less than or equal to 0.05) in relation to the functionality of the precooked flour and mixtures. The results obtained revealed that the applied process markedly improve the functional properties and nutritional value of the enriched flour, and of the "arepas" prepared from them.

[Obtaining protein fractions from commercial sesame cakes (Sesamum indicum)]

Sesame press cake represents an important potential protein source for human consumption. Some of the limiting factors are its high crude fiber content, oxalic acid content, and its bitter taste. By fractionation of solvent-extracted sesame meal, several preparations were obtained which were analyzed for their nutrient content, protein utilization and digestibility. PER values were low, and supplementation with lysine, skim-milk powder, soymeal or fish meal, improved the PER values considerably. Based on these findings, formulas for use as a protein supplement for children are presented.

[Formulation of a rice-based beverage of high nutritive value]

The purpose of this work was the production of a beverage with a nutritive value similar to that of milk, but available at a lower cost. A traditional beverage in Venezuela, "Chicha de Arroz" (Rice Chicha), was chosen. The various formulas studied were based on rice, non-fat milk and different kinds of soy flour, in addition to sugar, vegetable oil, vitamins, ferrous sulfate and different flavors. A product with protein and caloric values similar to those of milk was obtained. Twenty formulas were prepared and submitted to physico-chemical, microbiological and sensorial evaluations with respect to flavor, color, viscosity and stability during period of refrigeration. The most adequate formula was prepared on a pilot-plant scale. Rat assays gave the same PER results as those of casein. Consumer acceptability was tested on 1,080 school children, and showed to be greater than 95%. The stability was superior to that of milk and the cost, approximately three-fourths that of the latter. In the school-snack program of the National Institute of Nutrition, milk is now being replaced by this Chicha.

[Nutritional studies with rice bran]

The nutritional value and proximate chemical composition of five samples of rice bran taken from different varieties of rice grown in Venezuela was studied. Thiamin, niacin, riboflavin and tryptophan, lysine, methionine and cystine were analyzed. The apparent protein digestibility was between 59 an 74%, and the Protein Efficiency Ratio (PER) between 1.19 and 2.31. The supplementation with threonine increased the Protein Efficiency Ratio in 12%, but supplementation with tryptophan did not improve it neither alone nor combined with threonine. Combinations with corn and soyflour that simulate formulas for infants showed that there is a protein supplementation in these mixtures. Some combinations with corn, soy flour, and rice bran had the same P.E.R. as casein. The rice bran is an excellent source of vitamins and minerals in these combinations. The results showed that rice bran has potential value for human consumption.