Intracranial self stimulation upregulates the expression of synaptic plasticity related genes and Arc protein expression in rat hippocampus.

Post-training lateral hypothalamus (LH) intracranial self stimulation (ICSS) has a reliable enhancing effect on explicit memory formation evaluated in hippocampus-dependent tasks such as the Morris water maze. In this study, the effects of ICSS on gene expression in the hippocampus are examined 4.5 h post treatment by using oligonucleotide microarray and real-time PCR, and by measuring Arc protein levels in the different layers of hippocampal subfields through immunofluorescence. The microarray data analysis resulted in 65 significantly regulated genes in rat ICSS hippocampi compared to sham, including cAMP-mediated signaling as one of the most significantly enriched Database for Annotation, Visualization and Integrated Discovery (DAVID) functional categories. In particular, expression of CREB-dependent synaptic plasticity related genes (c-Fos, Arc, Bdnf, Ptgs-2 and Crem and Icer) was regulated in a time-dependent manner following treatment administration. Immunofluorescence results showed that ICSS treatment induced a significant increase in Arc protein expression in CA1 and DG hippocampal subfields. This empirical evidence supports our hypothesis that the effect of ICSS on improved or restored memory functions might be mediated by increased hippocampal expression of activity-dependent synaptic plasticity related genes, including Arc protein expression, as neural mechanisms related to memory consolidation.

How do disorders related to hospitalisation influence haemodialysis patients' nutrition?

INTRODUCTION: Hospitalizations are frequent in hemodialysis patients and is often accompanied by nutritional deterioration showed by a loss of weight and a reduction of albumin serum levels. This phenomenon is related with length of stay having its origin in a complex interplay of factors. Our aim in this study was to analyze if changes in body weight and other nutritional parameters are influenced by the illnesses presented during hospitalization. PATIENTS AND METHODS: Over a period of three years, we retrospectively chose chronic haemodialysis patients that were admitted for more than four days, excluding those cases that died in the hospital. We randomly chose one admission episode per patient so as to avoid excessive weighing of repeated admissions. We took data concerning weight changes, pre-admission and post-discharge analytical results, analytical results following first week of hospital stay, disorders causing hospital admission and those that developed during the hospital stay. We created a point score system to record the total of illnesses presented. RESULTS: The study included 77 patients, aged 67±12 years and having undergone haemodialysis for 31±34 months. Hospital stay was 17.8±12.6 days (median, 12 days). We observed that many patients admitted for digestive and osteoarticular disorders, heart failure or coronary syndrome lost more weight during their hospital stay, although no significant differences were reached. The total number of disorders suffered during the hospital stay was independent of the cause of hospitalisation. Anaemia,heart arrhythmias and signs of heart failure were associated with longer hospital stays, however it was only anaemia that was significantly related to greater weight loss. Weight loss was not related to surgery or infections. Albumin levels during the first week of hospital stay were different depending on the disorder upon admission. It was lower when the patients were admitted for digestive disorders (ANOVA, P=.05). Changes in albumin and creatinine levels before and after the hospital stay did not differ among disorders. We observed a relationship between having presented with more disorders during the stay and a longer stay, lower initial albumin and greater weight loss following discharge. In the multivariate analysis, we found the following weight loss predictors: stay, anaemia, and sepsis. We also found the following hospital stay predictors:Charlson's comorbidity index, heart arrhythmias, anaemia, sepsis and surgery. CONCLUSIONS: Malnutrition during the hospital stay depends on the duration and the number of disorders that develop during this time, the cause of admission having less impact on this. Albumin levels decrease earlier in patients that are going to develop more disorders during hospital stay.

Intracranial self-stimulation induces expression of learning and memory-related genes in rat amygdala.

Intracranial self-stimulation (ICSS) in the lateral hypothalamus improves memory when administered immediately after a training session. In our laboratory, ICSS has been shown as a very reliable way to increase two-way active avoidance (TWAA) conditioning, an amygdala-dependent task. The aim of this work was to study, in the rat amygdala, anatomical and molecular aspects of ICSS, using the same parameters facilitating TWAA. First, we examined the activation of ipsilateral and contralateral lateral (LA) and basolateral (BLA) amygdala, the main amygdalar regions involved in the TWAA, by the immunohistochemical determination of c-Fos protein expression. Second, we tested the effects of the ICSS treatment on the expression of 14 genes related to learning and memory processes using real-time polymerase chain reaction. Results showed a bilateral increase in c-Fos protein expression in LA and BLA nuclei after ICSS treatment. We also found that Fos, brain-derived nerve growth factor (BDNF), Arc, inducible cAMP early repressor (ICER), COX-2, Dnajb1, FKpb5 and Ret genes were upregulated in the amygdala 90 min and 4.5 h post ICSS. From this set of genes, BDNF, Arc and ICER are functionally associated with the cAMP-responsive element-mediated gene transcription molecular pathway that plays a pivotal role in memory, whereas Dnajb1 and Ret are associated with protein folding required for plasticity or neuroprotection. Our results suggest that ICSS induces expression of genes related with synaptic plasticity and protein folding functions in the rat amygdaloid area, which may be involved in the molecular mechanisms by which ICSS may improve or restore memory functions related to this brain structure.

[Loss of weight in hemodialysis patients after hospitalization is related with length of stay and degree of inflammation]. / La pérdida de peso en pacientes en hemodiálisis tras su hospitalización tiene relación con la duración de la estancia y con el grado de inflamación.

BACKGROUND: It is frequent to observe that hemodialysis patients suffer important loss of weight during hospital stay. This issue has not been investigated previously. Our aim in this study was to analyze factors associated with this loss of weight and what changes occur after admission in biochemical parameters with nutritional interest. PATIENTS AND METHODS: We retrospectively selected patients undergoing chronic hemodialysis who were admitted at hospital for acute or chronic pathologies, with a minimum length of stay of 4 days, taking only one episode of admission per patient. We chose loss of weight observed at hospital discharge, at 2 and 4 weeks later and we also collected routine laboratory data and adequacy parameters before and after the hospital admission and basic biochemical parameters in the first week of hospital stay. RESULTS: We included 77 patients, with 67±12 years and 30±34 months in dialysis. Forty (51.9%) were female (51.9%) and 22 diabetics (28.6%). Length of stay was 17.8±12.6 days (median 12). There were 70.4% patients who suffered a loss of weight at discharge and 81.4% at 4 weeks, without differences in sex or diabetes. Weight decreased significantly with a mean of -1.09 kg (95%CI -0.73 to -1.44). After 2 weeks the loss of weight was -1.64 kg (95%CI -1.21 a -2.07 kg) and after 4 weeks was -1.94 kg (95%CI -1.47 a -2.42 kg). Comparing parameters before and after admission, we observed a significantly decrease in serum urea levels (before 134±40 vs after 119±36 mg/dl; p= 0.001), creatinine (before 8.1±2.6 vs after 7.5±2.6 mg/dl; p < 0.001), phosphate (before 5.2±1.7 vs after 4.3±1.5 mg/dl; p < 0.001) and albumin (before 3.70±0.48 vs after 3.56±0.58 g/dl; p=0.05), without changes in adequacy parameters. Greater loss of weight at 4 weeks from discharge was correlated with larger length of stay (r= 0.41; p < 0.001), greater body mass index at admission (r= -0.23; p=0.05) and lower serum albumin at admission (r= 0.39; p= 0.012). It was also correlated with a lower serum albumin (r= 0.27; p=0.05), lower creatinine (r= 0.30; p= 0.02) and lower protein intake (nPNA) (r= 0.47; p= 0.002) after discharge. Lower serum albumin levels at admission were correlated with greater decreases of creatinine after discharge (r= 0.42; p= 0.009) and larger length of stay (r= -0.61; p < 0.001). Employing multivariate analysis we found that loss of weight was associated to length of stay and serum potassium levels before admission. CONCLUSIONS: Hospitalization of hemodialysis patients have a negative nutritional impact causing a significant loss of weight, probably reflecting a reduction of muscle mass. We found that length of stay in hospital is a basic factor associated with this nutritional impairment. The pathologies promoting hospitalization could influence this derangement through inflammation but this hypothesis should be investigated.

Intracranial self-stimulation to the lateral hypothalamus, a memory improving treatment, results in hippocampal changes in gene expression.

Intracranial self-stimulation (ICSS) within the medial forebrain bundle of the lateral hypothalamus (LH) facilitates consolidation of implicit and explicit memories for a variety of learning paradigms in rats. However, the neural and molecular mechanisms involved in memory facilitation by ICSS are not known. Here, we investigated the influence of ICSS treatment on hippocampal gene expression in order to identify potential signaling pathways and cellular processes involved in ICSS-mediated cognitive improvements. Immunohistochemistry studies demonstrated that ICSS caused a rapid induction of c-Fos expression in hippocampal cornu ammonis (CA) 3 and dentatus gyrus areas. Moreover, using microarray or quantitative real-time polymerase chain reaction (PCR) analysis, we showed that ICSS modulates the expression of 62 hippocampal genes shortly after training. Most of the proteins encoded by these genes, such as calmodulin-dependent-phosphodiesterase 1 A (Pde1a), are part of signal transduction machineries or are related to anti-apoptosis, as heat shock 70 kDa protein 1A (Hspa1a). Importantly, 10 of the regulated genes have been previously related with learning and memory or neural plasticity, including the cocaine and amphetamine-regulated transcript (Cart), adenylate cyclase activating polypeptide 1 (Adcyap1), serum/glucocorticoid regulated kinase (Sgk), Ret proto-oncogene (Ret), and Fos. The fact that the Fos gene was differentially expressed in our microarray experiments validated our findings from our immunohistochemical studies mentioned above. In addition, using quantitative real-time PCR, we confirmed the observed expression changes for several of the genes identified by our microarray analyses. Our results suggest that ICSS may facilitate learning and memory by regulation of multiple signaling pathways in the hippocampus that may promote neuroplasticity.

Intracranial self-stimulation facilitates a spatial learning and memory task in the Morris water maze.

Learning and memory improvement by post-training intracranial self-stimulation has been observed mostly in implicit tasks, such as active avoidance, which are acquired with multiple trials and originate rigid behavioral responses, in rats. Here we wanted to know whether post-training self-stimulation is also able to facilitate a spatial task which requires a flexible behavioral response in the Morris water maze. Three experiments were run with Wistar rats. In each of them subjects were given at least five acquisition sessions, one daily, consisting of 2-min trials. Starting from a random variable position, rats had to swim in a pool until they located a hidden platform with a cue located on its opposite site. Each daily session was followed by an immediate treatment of intracranial self-stimulation. Control subjects did not receive the self-stimulation treatment but were instead placed in the self-stimulation box for 45 min after each training session. In the three successive experiments, independent groups of rats were given five, three and one trial per session, respectively. Temporal latencies and trajectories to locate the platform were measured for each subject. Three days after the last acquisition session, the animals were placed again in the pool for 60 s but without the platform and the time spent in each quadrant and the swim trajectories were registered for each subject. A strong and consistent improvement of performance was observed in the self-stimulated rats when they were given only one trial per session, i.e. when learning was more difficult. These findings agree with our previous data showing the capacity of post-training self-stimulation to improve memory especially in rats with little training or low conditioning levels, and clearly prove that post-training self-stimulation can also improve spatial learning and memory.

[Efficacy of rasburicase therapy in obstructive renal failure secondary to urolithiasis: a novel therapeutic option]. / Eficacia de la rasburicasa en el fracaso renal agudo obstructivo por litiasis: una nueva opción terapéutica.

The overall incidence of nephrolithiasis-related acute and chronic renal failure is poorly known and surely underestimated. However, obstructive nephropathy represents a potentially curable form of kidney disease that often requires for managing an instrumentation of urinary tract. Rasburicase is an enzyme that transforms uric acid to allantoin, a compound more water soluble that will be excreted by the kidney more easily. Rasburicase has been proven to be an effective therapy for prevention of tumour lysis syndrome. But it also represents an interesting new option in managing hyperuricemia in patients with severe tophaceous gout. We administered rasburicase intravenously (0.20 mg/kg/day, for 2 days) in 2 adults with acute obstructive nephropathy from renal calculi, which was receiving temporary haemodialysis. Rasburicase produced a sharp polyuria 12-18 hours after its administration accompanied with a fast reduction of serum creatinine levels, that returned to normal range without further dialysis. If we suppose that rasburicase can pass through glomerular filter by its relatively low molecular weight, it could dissolve tubular uric acid crystals in acute renal failure associated to tumour lysis syndrome, providing the restoration of renal function. But we also could postulate that rasburicase can act in urinary tract, fragmentating renal calculi, promoting relief of obstructive uropathy and the resolution of renal failure. We suggest rasburicase should be tried in this new indication to prove its potential efficacy.

[Complete remission of nephrotic syndrome with methylprednisolone pulses in an adult with Schönlein-Henoch purpura]. / Remisión completa de síndrome nefrótico con pulsos de metil-prednisolona en un adulto con púrpura de Schönlein-Henoch.

Henoch-Schönlein purpura is a systemic vasculitis that occurs most frequently in childhood. Massive proteinuria, renal impairement at onset and histologic severity in renal biopsy are considered the main risk factors for deterioration of renal function at long-term. We report a 24 years-old woman with Henoch-Schönlein purpura who developped a severe nephrotic syndrome with microhematuria and normal renal function. Renal biopsy showed a diffuse endocapillary proliferative glomerulonephritis with less than 50% crescents (type IIIB of ISKDC classification). As their potential bad prognosis we decided to treat with methyl-prednisolone pulses (3 x 500 mg in months 0, 3 and 5) accompanied by maintenance treatment with prednisone (0,5 mg/kg/every other day) for 9 months. We observed with this protocol complete remission of nephritis with preservation of renal function.

Intracranial self-stimulation in the parafascicular nucleus of the rat.

A behavioral analysis of intracranial self-stimulation was provided for parafascicular nucleus. To evaluate whether intracranial self-stimulation in this nucleus could be site-specific and to determine if the positive sites are the same parafascicular areas that facilitate learning when stimulated, rats were tested via monopolar electrodes situated throughout the parafascicular nucleus. Animals were trained to self-stimulate by pressing a lever in a conventional Skinner box (1-5 sessions). Twenty-two of the 42 animals included in the study, had the electrode at the parafascicular nucleus. Only two of them showed intracranial self-stimulation. Histological analyses indicated that the latter rats had the electrode implanted at the anterior area of the medial parafascicular. Other two animals also showed intracranial self-stimulation but they had the electrode in a more posterior brain region, between the Dark-schewitsch nucleus and the red nucleus. The animals implanted at the parafascicular showed higher response rates than the other two rats. These results confirm that: (a) the anterior region of the medial parafascicular is a positive site for stable and regular intracranial self-stimulation behavior, and (b) these positive sites do not coincide with the parafascicular regions related to learning improvement.

Involvement of the parafascicular nucleus in the facilitative effect of intracranial self-stimulation on active avoidance in rats.

To evaluate whether parafascicular nucleus (PF) is involved in the facilitative effect of lateral hypothalamic intracranial self-stimulation (LH-ICSS) on two-way active avoidance acquisition (5 sessions, 10 trials each, one daily) and long-term retention (10 days), rats were lesioned bilaterally at the PF and implanted with an electrode aimed at the LH to obtain ICSS behavior. After each acquisition session rats were allowed to self-administer 2500 trains of LH-ICSS. The main results were: (1) LH-ICSS facilitated the acquisition and retention of conditioning; (2) PF lesions impaired both acquisition and retention of two-way active avoidance; (3) there was a positive relationship between PF lesions size and learning disruption, and (4) LH-ICSS failed to facilitate learning when PF was lesioned. We concluded that the lesion size is a critical variable to evaluate the effects of PF lesions on learning and memory, and that LH-ICSS treatment may exert their effects through the PF nucleus or, at least, the integrity of PF is required for LH-ICSS to improve clearly the task.

Facilitation of a distributed shuttle-box conditioning with posttraining intracranial self-stimulation in old rats.

Old Wistar rats (16-17 months) were trained in a two-way active avoidance task for 5 consecutive days (10 trials/day). Immediately after each training session a lateral hypothalamic intracranial self-stimulation session (ICSS group) or a sham-treatment session (Control group) was given to the animals. Long-term retention was tested 7 days after the last acquisition session. ICSS treatment led to a significant improvement in acquisition. In the long-term retention session the level of avoidance in both groups was similar to that achieved in the last acquisition session, although differences among groups failed to reach statistical significance. These results are compared with those obtained in previous experiments with young adult rats. While ICSS facilitated the process of acquisition in both young and old rats (however, it was much more powerful in young animals), further experiments are needed to elucidate whether this effect is long-lasting in old rats, as occurs in young adult subjects.

Tuberomammillary nucleus lesion facilitates two-way active avoidance retention in rats.

To evaluate whether the tuberomammillary nucleus might be involved in the acquisition and/or retention of a two-way active avoidance conditioning, rats were given a unilateral lesion of the tuberomammillary nucleus (E2 region) 24 h prior to the first conditioning session. Four learning sessions were performed: one acquisition and 3 retention sessions (short-term, 24 h; and long-term, 8 and 18 days). Results showed that the lesion facilitated the long-term retention of conditioning, but no effects were observed on acquisition and short-term retention. Since rewarding intracranial electrical stimulation seems to be a consistent way to facilitate learning and memory processes, and tuberomammillary lesion has been shown to improve intracranial self-stimulation behavior (ICSS), we suggest that lesions in the present experiment could have facilitated two-way active avoidance retention by enhancing the function of brain reward mechanisms.

Shuttle-box memory facilitation by posttraining intracranial self-stimulation: differential effects in rats with high and low basic conditioning levels.

The effects of intracranial self-stimulation (ICSS) on retention (after 24 hr, 7, 15, or 60 days) of a massed 2-way active avoidance task were studied in independent groups of rats. All groups showed a higher performance on the retention session than on the acquisition one. In the control subjects, the higher retention performances were observed in the 7- and 15-day groups. However, the ICSS treatment facilitated the 24-hr retention compared with its control group, allowing the treated subjects to achieve the same level of performance on the 24-hr retention session than that achieved by the control rats at the 7-day retention test. In the 24-hr groups, the facilitatory ICSS effect was stronger in the subjects with a low level of conditioning and weaker in those with a high level. Results suggest that posttraining ICSS accelerates memory consolidation and equalizes the performance of poor and good learners.

Effects of parafascicular electrical stimulation and lesion upon two-way active avoidance in rats.

To evaluate a possible role of the parafascicular nucleus (PF) in modulating distributed two-way active avoidance acquisition and long-term retention (LTR), we designed two experiments. Experiment I was aimed at checking whether posttraining PF intracranial electrical stimulation (PF ICS) can improve the acquisition and/or the LTR of the task. All subjects (Ss, male Wistar rats) were implanted with an electrode at the PF. After each learning session two groups of Ss were stimulated for 10 (ICS-10 group) and 5 (ICS-5 group) min, respectively. A Control group never received PF ICS, while Ss in an ICS-Control group received PF ICS only during a previous search for a nonconvulsive current intensity. Unexpectedly, the ICS-Control group showed poor performance of the task compared to the remaining groups. Since the histological analyses showed that the pretraining ICS treatment produced some PF tissue lesion, Experiment II was aimed at evaluating the effects upon the same task of (1) pretraining PF electrolytical lesions (PF-Lesion group) and (2) posttraining PF ICS treatment (ICS group) at a lower current intensity and without a previous search for nonconvulsive current intensity. PF pretraining lesion decreased conditioning, while posttraining PF ICS did not affect it. We concluded that PF could have a modulatory role in acquisition, and might also contribute to posttraining consolidation, of a distributed two-way active avoidance.

The tuberomammillary nucleus region as a reinforcement inhibiting substrate: facilitation of ipsihypothalamic self-stimulation by unilateral ibotenic acid lesions.

The tuberomammillary nucleus (TM), located in the posterior hypothalamic region, consists of five subgroups and is the only known source of brain histamine. Knowledge about the function of this nucleus is still scarce. In a previous study we found an increase in the rate of ipsihemispheric hypothalamic self-stimulation following a dc lesion in the rostroventral part of this nucleus, suggesting that this region has an inhibitory action on a neuronal reward system or on the brain's reinforcement mechanism. In the present study we examined whether this facilitating effect on reinforcement was due to the destruction of fibers passing through the lesion area or of intrinsic cells, by lesioning subgroups of the TM with ibotenic acid, an excitatory amino acid, that selectively destroys neural cell bodies, leaving fibers largely intact. Following such lesions in the rostroventral part of the TM the operant response rates increased over the six days of testing when the animals stimulated themselves in the lateral hypothalamus in the hemisphere located ipsilateral but not contralateral to the lesion. No significant changes in response rate occurred following the lesion in the caudal part of the ventral TM. The results indicate that the region influenced by the lesion exerts inhibitory control over lateral hypothalamic self-stimulation, and that it is possible that histamine-containing neurons are involved in this effect.

Improvement of shuttle-box avoidance with post-training intracranial self-stimulation, in rats: a parametric study.

Rats were trained in a two-way active avoidance task followed immediately by a lateral hypothalamic intracranial self-stimulation (ICSS) treatment, during 5 consecutive days. The effects of the number of ICSS trains allowed (0, 500, 2500 or 4500) were studied upon acquisition and long-term retention (LTR, 10 and 30 days). The number of ICSS trains administered and the number of avoidances at the last acquisition session (5th) showed a positive lineal relation, that is, the more number of ICSS trains, the more number of avoidances. The level of learning achieved during the 5th session was maintained after the LTR periods in all experimental groups. It is concluded that the number of ICSS trains could be a critical parameter in the facilitatory effect of lateral hypothalamic ICSS upon learning, and it is suggested that the facilitatory effect of post-training lateral hypothalamic ICSS might be due to the activation of general activatory neural systems.

Correlations between paradoxical sleep and shuttle-box conditioning in rats.

Eighteen male Wistar rats were given one daily two-way active avoidance conditioning session followed immediately by 5 hr of sleep recording, for 5 consecutive days. The group of rats that achieved 80% or greater avoidance in some of the 5 training sessions showed significant linear increases of paradoxical sleep (PS), compared with baseline levels, throughout the successive conditioning sessions. Furthermore, (a) the group of rats showing PS increases (more than 1 SD above baseline) after some of the training sessions achieved a significantly higher final number of avoidances than the remaining animals: (b) a high and positive correlation was observed between avoidance increases in the 3rd conditioning session and previous PS; and (c) maximum increases in correct performance often occurred following high PS increases. It is concluded that PS increases facilitate the consolidation of learning.

Improvement of shuttle-box learning with pre- and post-trial intracranial self-stimulation in rats.

The effects of intracranial self-stimulation (ICSS) in the lateral hypothalamus upon the acquisition and long-term retention (LTR) of shuttle box avoidance conditioning were studied in Wistar rats. Two groups of subjects learned the avoidance task in 5 daily training sessions and were allowed to self-stimulate either before (Pre-ICSS group), or after (Post-ICSS group) each training session. A control group received training but no ICSS. Ten days following the last training session, LTR of the task was determined in one avoidance session without ICSS. A fourth group was added post-hoc which was allowed to self-stimulate before the training sessions as well as before the LTR test. Both the Post-ICSS and Pre-ICSS groups improved in acquisition of the learned response over the successive training sessions, as compared with Controls. In the LTR test, the animals of the Post-ICSS group maintained the response level achieved in the last acquisition session. In contrast, the subjects of the Pre-ICSS group showed a significant decrease of the same response, unless they were given ICSS treatment prior to the LTR test. This may indicate a 'state-dependent learning' effect being responsible for the decrease in the LTR observed in Pre-ICSS group. Because both pre- and post-training ICSS treatments improved the acquisition and the LTR of the learned response, it is suggested that the contingency of the treatment with training (that is, ICSS treatment immediately after the training sessions) is not a necessary condition to facilitate the acquisition and the consolidation of two-way active avoidance learning.