Exploratory Study of the Influence of Posture and Hand Task on Corticomotor Excitability of Upper Extremity Muscles After Stroke.

OBJECTIVE: To explore the interaction between postural stability and hand task on the corticospinal excitability (CE) of upper extremity muscles and how it is affected by lesion location. DESIGN: Cross-sectional explorative survey. SETTING: Inpatient rehabilitation center. PARTICIPANTS: Participants (N=81) were neurologically healthy subjects (volunteer sample, n=36) and patients with stroke (convenience sample, n=45; mean time since stroke, 45d), stratified according to lesion location: pure subcortical strokes (n=25) and strokes with cortical involvement (n=20). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Motor-evoked potentials were recorded simultaneously from the first dorsal interosseus (FDI) muscle and biceps brachii (BB) during rest and during low and forceful activation of the FDI in 4 different postural positions (supine, sitting, sitting unsupported, standing) and compared. RESULTS: Posture modulated CE of the FDI and BB during performance of a motor task but not at rest. The influence of postural position on CE of the FDI depended on force demand and lesion location: the control and subcortical stroke group demonstrated significantly higher CE of the FDI when performing the forceful task in the supine and stable sitting positions, respectively, compared with standing. In contrast, the cortical stroke group exhibited significantly higher CE of the FDI when performing the low-force task in a stable sitting position compared with standing. CONCLUSIONS: Posture influences CE of the FDI and BB in healthy subjects and patients with stroke differentially depending on hand task, but not at rest. A stable sitting posture increased excitability of the FDI in patients with stroke. These findings imply that hand rehabilitation protocols may be influenced by posture.

Accumulation of renin and imidazolone in peritubular capillary endothelial cells in insulin-resistant hypertensive rats.

BACKGROUND: Peritubular endothelium plays a key role in the development and progression of diabetic and nondiabetic chronic kidney disease. Renal injury in disorders of glucose metabolism may appear as early as in the stage of impaired glucose tolerance (IGT) and is accelerated by hypertension. The aim of our study was to investigate renal histology in rats with hypertension and IGT, with special emphasis on the peritubular endothelium. METHODS: Hypertension and IGT (H/IGT) were provoked in adult male Wistar rats by bilateral administration of methylglyoxal into the ventromedial hypothalamus. Immunohistochemistry with anti-renin and anti-imidazolone antibodies and immunoelectron microscopy with anti-renin antibody were performed. RESULTS: H/IGT rats showed tubulointerstitial fibrosis as well as renin and imidazolone staining in the papillary region. The patterns of immunostaining for renin and imidazolone were similar to that of endothelium. On electron microscopy, peritubular capillary endothelial cells and to a less extent, tubular epithelial cells showed renin positivity. DISCUSSION: Impaired glucose tolerance complicated with hypertension leads to tubulointerstitial fibrosis in rat kidney. Imidazolone deposition and renin production in peritubular capillary endothelial cells may play a role in the development of tubulointerstitial fibrosis.

Taste reactivity deficit in anorexia nervosa.

AIM: Anorexia nervosa is a complex psychiatric disorder posing a rapidly increasing burden on modern societies. Our purpose was to clarify perceptual-motivational aspects of gustatory disturbances in the disease. METHODS: A taste reactivity test, with the use of all five primary qualities in two concentrations, was performed in restrictive-type anorexic patients, and their hedonic evaluations were compared to those of age-matched healthy control subjects. RESULTS: The patients gave significantly lower pleasantness scores for pleasant taste stimuli compared with controls. The differences were the greatest for the lower concentration sucrose, umami and sodium chloride. Ratings given for the aversive taste stimuli were similar in both experimental groups. CONCLUSION: Our findings contribute to a better understanding of complex symptoms of anorexia nervosa, and may also help to develop more effective cognitive-behavioral therapies.

Homeostatic alterations after IL-1beta microinjection into the nucleus accumbens of the rat.

The present study investigates the effects of direct administration of interleukin-1beta (IL-1beta) into the nucleus accumbens (NAcc) on homeostatic regulation. Short- and long-term food intakes (FI), water intakes (WI) and body temperature (BT) were measured before and after bilateral microinjection of IL-1beta (with or without paracetamol pretreatment) into the NAcc of Wistar rats, and the effects were compared with those found in vehicle treated control animals. In addition, blood glucose levels, along with a glucose tolerance test (GTT), and plasma concentrations of metabolic parameters, such as total cholesterol, triglycerides, HDL, LDL and uric acid were determined in cytokine treated and control rats. Short-term FI and WI were suppressed after intraaccumbens application of IL-1beta. A significant increase of BT was also observed after the cytokine microinjection. Pretreatment with paracetamol failed to influence the anorexigenic, adipsogenic, and pyrogenic effects of IL-1beta. A definite glucose intolerance of the cytokine treated animals and their pathologically elevated blood glucose levels became obvious in the acute GTT. Following IL-1beta microinjection, plasma levels of triglycerides, total cholesterol and LDL were found increased. Our present findings show that the NAcc is an important site of action of IL-1beta mediated processes in central homeostatic regulation.

Taste reactivity alterations after IL-1beta microinjection into the ventromedial hypothalamic nucleus of the rat.

The ventromedial hypothalamic nucleus (VMH) is a central site of action of interleukin-1beta (IL-1beta) induced feeding disturbances. This study was designed to elucidate taste-related perceptual and motivational processes potentially contributing to the anorexia and adipsia seen after bilateral IL-1beta microinjection into the VMH. A saccharin conditioned taste aversion (CTA) paradigm was tested after the central IL-1beta administration. To further investigate whether gustatory deficits are involved in development of the feeding alterations, IL-1beta induced changes of taste responsiveness were also studied in taste reactivity tests. Administration of the cytokine into the VMH did not cause the development of CTA. During taste reactivity tests, however, IL-1beta treated rats displayed significantly poorer ingestive reactions to pleasant taste stimuli than did animals of the control group. In addition, the aversive responses of IL-1beta injected rats to pleasant tastes were significantly more robust than those of control animals. The cytokine treated animals also showed stronger aversion than ingestion to hedonically positive tastes. The present findings indicate that (1) anorexigenic and adipsogenic consequences of IL-1beta microinjection into the VMH are not due to development of cytokine induced CTA; and (2) hedonic responsiveness to palatable tastes is processed by IL-1beta mediated neural mechanisms in the VMH.

Categorization of biologically significant objects, food and gender, in rhesus monkeys. I. Behavioral study.

Macaque monkeys have a highly evolved visual system comparable to that of humans. One of the important visual functions is performing discriminations among biologically significant objects such as food or heterosexual partners. In the present study, we examined whether rhesus monkeys could categorize two-dimensional images related to food or gender using a visual discrimination task. Three rhesus monkeys were trained to make distinctions of food from non-food items, and between male and female monkeys, using 60 or more different pictures of each category. After more than 9 months of training, the monkeys discriminated a variety of foods from non-food and different males from females with more than 80% accuracy, even when the stimuli were used for the first time or presented only once in a session. The proportion of correct responses and response latencies showed better performance in discrimination of food/non-food than that of gender. The results suggest that rhesus monkeys are able to perform visual discrimination of highly abstract biologically significant categories with better performance in a food-related category than a gender-related one, using two-dimensional visual information.

Glucose-monitoring neurons in the nucleus accumbens.

The nucleus accumbens, a key structure of the limbic circuitry, is involved in the regulation of motivated behaviors. The accumbens performs its roles via interconnections with brain areas where glucose-monitoring neurons have been localized. To search for such integrative chemosensory cells here, extracellular single neuron activity was recorded in the nucleus accumbens of Wistar rats by means of multibarreled glass microelectrodes during microelectrophoretic administration of D-glucose and other chemicals. Every fourth neuron tested changed in activity in response to glucose. Accumbens cells also displayed distinct gamma-amino-n-butyric acid type sensitivity. It is suggested that differential distribution of the chemosensory units, demonstrated between subdivisions of the nucleus accumbens, has particular significance with respect to functional dichotomy of the shell and core subregions.

Homeostatic alterations induced by interleukin-1beta microinjection into the orbitofrontal cortex in the rat.

The present experiments were designed to elucidate the effect of direct orbitofrontal cortical administration of interleukin-1beta (IL-1beta) on the homeostatic regulation. Short- and long-term food intakes (FI), water intakes and body temperature (BT) were measured before and after a bilateral microinjection of IL-1beta (with or without paracetamol /P/ pretreatment) into the orbitofrontal cortex (OBF) of Wistar rats, and the effects were compared with those found in vehicle-treated and i.p. injected IL-1beta, IL-1beta+P or control animals. In addition, blood glucose levels (BGLs), along a glucose tolerance test, and plasma concentrations of insulin, leptin, cholesterol, triglycerides and urate were determined in cytokine treated and control rats. Short-term FI was suppressed after orbitofrontal cortical or peripheral application of IL-1beta. In the long-term FI, however, there was no significant difference among the groups. Cytokine microinjection into the OBF, similar to the i.p. administration, was also followed by a significant increase in BT. Pretreatment with P failed to influence the anorexigenic and hyperthermic effects of the centrally administered IL-1beta. The sugar load led to a diabetes-like prolonged elevation of BGL in the IL-1beta treated animals. Following cytokine administration, plasma levels of insulin and that of triglycerides were found decreased, whereas that of uric acid increased. The present findings confirm that the OBF is one of the neural routes through which IL-1beta exerts modulatory effect on the central homeostatic regulation.

Homeostatic alterations after intrapallidal microinjection of interleukin-1beta in the rat.

To elucidate the homeostatic consequences of direct pallidal administration of interleukin-1beta (IL-1beta), short- (2 h) and long-term (12 h) food intakes, water intake and body temperature were measured after bilateral microinjection of IL-1beta (with or without paracetamol/PAR/pretreatment) into the ventro-medial part of the globus pallidus (GP). The effects were compared with those found in vehicle- or vehicle+PAR-treated control animals and intraperitoneally (i.p.) injected IL-1beta, IL-1beta+PAR or control rats. Direct GP microinjection of IL-1beta, similar to the peripheral (i.p.) administrations, reduced remarkably short-term food intake in food deprived animals. However, there were no significant differences among the groups in long-term food intakes and in water intakes as well. IL-1beta microinjection into the GP caused a significant increase in body temperature. This IL-1beta induced hyperthermia was attenuated by PAR pretreatment, whereas food intake was not affected. Results of the electrophysiological experiments revealed substantial changes in GP extracellular single neuron activity in response to the microelectrophoretic administration of IL-1beta. The present findings, along with previous data, are discussed in terms of the glucose-monitoring neural circuitry through which cytokines exert their direct modulatory effect on central homeostatic regulation.

Single neuron activity changes to interleukin-1beta in the orbitofrontal cortex of the rat.

The orbitofrontal cortex (OBF) is known to play important roles in various regulatory processes. Our preliminary behavioral studies showed homeostatic alterations after orbitofrontal cortical microinjection of interleukin-1beta (IL-1beta) in the rat. To elucidate whether the above alterations were due to direct neuronal action of the cytokine, extracellular single neuron activity was recorded in the OBF of anesthetized rats by means of tungsten fiber multibarreled glass microelectrodes during microelectrophoretic administration of IL-1beta. More than half (56%) of all cells tested changed in firing rate in response to IL-1beta. Approximately 90% of these cytokine-modulated neurons were also sensitive to microelectrophoretically applied d-glucose, that is, proved to be the elements of the central glucose-monitoring neural network. The present findings demonstrate that IL-1beta can exert direct modulatory role on neurons in the OBF.