Biochemical compartmentation of fish tissues: chronic toxicity of mercuric nitrate on visceral phosphomonoesterases in Channa punctatus (Bloch)

Effect of sub-lethal dose of mercuric nitrate was studied in anterior, middle and posterior regions of kidney, anterior and posterior regions of left and right liver lobes, cephalic, thoracic and caudal regions of muscle and left and right gill tissues of C. punctatus in relation to acid and alkaline phosphatase under chronic studies. Middle region of kidney registered maximum rise and fall of acid and alkaline phosphatase, respectively. Right lobe of liver showed more rise and fall of acid and alkaline phosphatase activity respectively. Similarly, left gill is more pronounced than the right one. The observed enzymatic variations were discussed in relation to the biochemical constituents and physiological coordination rendered by these tissues.     

Regional metabolic differences in the rat diaphragm

This study characterized the biochemical properties of the rat diaphragm by measuring the activities of selected citric acid cycle and glycolytic enzymes. The diaphragm was removed from 10 female Sprague-Dawley rats (180 days old) and dissected into five discrete anatomic regions: crural (region 1), left posterior costal (region 2), left anterior costal (region 3), right anterior costal (region 4), and right posterior costal (region 5). Sections were assayed for total protein concentration and the activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH). The SDH activity in the crural region was approximately 18% lower (P less than 0.05) than that in any costal region. Furthermore, protein concentration was significantly lower (P less than 0.05) in the crural region compared with all costal regions. In contrast, costal regions 2-5 did not significantly differ from each other in protein concentration or SDH activity. LDH activity did not differ significantly (P greater than 0.05) between regions. Finally, the LDH-to-SDH activity ratio was significantly higher (P less than 0.05) in the crural diaphragm compared with all costal regions. We conclude that the crural region of the rat diaphragm is significantly lower in oxidative capacity than all the costal regions. Investigators who use a rodent model to study diaphragmatic function and plasticity should consider the oxidative heterogeneity of the diaphragm when designing experiments.     

带状疱疹后遗神经痛患者脑基础活动改变的功能核磁共振研究

带状疱疹后遗神经痛(postherpetic neuralgia,PHN)是临床上一种慢性顽固性神经病理性疼痛,然而,对于其潜在的中枢机制还知之甚少.为了进一步探讨带状疱疹后遗神经痛患者的相关脑区活动,利用功能核磁共振成像低频振幅振荡(ALFF)技术观察带状疱疹后遗神经痛患者的基础脑区活动.8名带状疱疹后遗神经痛患者与8名性别、年龄相匹配的健康者行静息态功能磁共振(f MRI)成像扫描,用SPM8中的多重回归分析,在控制被试年龄、性别、教育年限的影响下,将每个体素的ALFF值同每个被试的病程、视觉模拟评分(visual analog scale,VAS)进行相关分析.与健康志愿者相比,PHN组与VAS评分相关的ALFF值增高的脑区有:右侧小脑后叶、前额叶背外侧区域(BA11/46/47)、右侧顶叶(BA40)、右侧舌回(BA17/18/19);与VAS评分相关的ALFF值降低的脑区有:右侧颞中回(BA21)、左侧舌回(BA17/18)、右侧小脑前叶、左侧后扣带回(BA30/19)和右侧中央前回(BA3/4/6);PHN组与病程相关的ALFF值增高的脑区有:右侧小脑后叶、前额叶背外侧区域(BA9/10/11/47)、左侧颞上回(BA38)、右侧顶叶和右侧舌回(BA17/18/19);与病程相关ALFF值降低的脑区有:左侧海马旁回(BA28)、右侧小脑前叶、左侧扣带回(BA24)、右侧颞上回(BA13)、左侧中央前回和右侧顶下小叶(BA39/40).研究结果提示,涉及疼痛的情绪、警觉行为、注意的脑区在带状疱疹后遗痛慢性疼痛的产生和维持中发挥重要作用.     

Functional regional asymmetry of the EEG intrahemispheric coherence in dogs during conditioning

Individual features of the regional interhemispheric relations in the brain were studied in dogs during alimentary conditioning. The electrical activity was recorded from symmetrical anterior (frontal and motor cortices) and posterior (visual and auditory cortices) areas of the neocortex. Comparison between the averaged left and right intrahemispheric EEG coherences revealed a dynamic character of interhemispheric relations dependent on the stage of conditioning. Individual features were shown. In a dog with strong type of the nervous system, in the anterior brain regions, the EEG coherence was higher in the left hemisphere than in the right one, whereas, on the contrary, in the posterior regions, the values were higher in the right than in the left hemisphere. In dogs with weak type of the nervous system, there was an inverse relationship. Thus, the spatial organization of the cortical electrical activity in the associative and projection brain areas was different.     

Increased left anterior insular and inferior prefrontal activity in post-stroke mania

ABSTRACT: BACKGROUND: Post-stroke mania is an infrequent complication after stroke, and the mechanisms underlying this disorder remain unclear. Although a contralesional release phenomenon has been implicated in post-stroke mania, empirical findings are lacking. Case Presentation: we preset a case report of post stroke mania. Single photon emission tomography (SPECT) was performed twice, during the manic state and during the remitted euthymic state.The first SPECT study performed during the manic state demonstrated hypoperfusion in the right temporal and frontal regions due to right putaminal hemorrhage. It also showed hyperperfusion in the inferior lateral prefrontal lobe, the temporal lobe, and the medial and lateral parts of the parietal lobe in the left hemisphere. The second SPECT study performed during the euthymic state demonstrated moderate improvement in the hypoperfusion in the right fronto-temporal regions. Furthermore, compared to the findings on the first SPECT study, the second study showed that the focal hyperperfusion in the anterior insular cortex, inferior lateral prefrontal lobes, and superior-middle temporal gyrus in the left hemisphere had vanished. CONCLUSION: Increased left inferior prefrontal and anterior insular activity and reduced extensive right fronto-temporal lobe activity are involved in the development of post-stroke mania.     

Interhemispheric differences in the spectral power and coherence of EEG rhythms in children with autism spectrum disorders

Electroencephalographic examination of boys aged 4–9 years with autism spectrum disorders (ASDs) showed spectral power values and coherence in high-frequency bands (20–60 Hz) in various brain areas were higher than normal. Differences in spectral power were greater in the anterior areas of the left hemisphere; differences in coherence, in the right anterior and posterior areas. Interhemispheric differences typical of healthy subjects were absent in the children with ASDs. The spectral power of the θ rhythm was lower in autism, especially in the left hemisphere. The spectral power of the α rhythm in the autistic children was lower than normal, especially in the posterior areas of the left hemisphere. The μ rhythm was higher than normal in spectral power and was localized in the right, rather than left, anterior areas. The children were examined again after corrective procedures. The α-rhythm spectral power increased (became closer to the norm) in the left posterior areas, while the γ-rhythm spectral power decreased (became closer to the norm) in the right anterior areas in some of the autistic children. The electrophysiological changes were associated with improved psychological testing results, especially in nonverbal measures.     

High glucose-6-phosphatase activity in non-pigmented epithelial cells of rabbit ciliary body.

For study of the origin of glucose in the aqueous humor, glucose-6-phosphatase (G6Pase) and hexokinase activities, and glycogen, were cytochemically examined in the ciliary body (CB) of rabbit. G6Pase activity was also assayed biochemically. The staining reaction for G6Pase activity was strong in the non-pigmented epithelium (NPE) in the pars plana and tips of ciliary processes in the region containing large ciliary pockets within the pars plicata. NPE cells contained abundant reaction product for G6Pase activity in the endoplasmic reticulum (ER) and nuclear envelope. However, NPE in other regions of the CB and pigmented epithelium (PE) of CB, and other areas surrounding the anterior and (PE) of CB, and other areas surrounding the anterior and posterior chambers, showed weak or no G6Pase staining reaction. Biochemical G6Pase activity in the whole ciliary body was relatively high. Both NPE and PE in the pars plana and the tips showed strong staining reaction for hexokinase activity but no staining for glycogen. Furthermore, NPE cells in the tips bore large aggregates of smooth ER and many Golgi apparati. These suggest that the high G6Pase activity in NPE cells in the pars plana and the tips is related to glucose release into the aqueous humor.     

Circadian rhythm in Leu-beta-naphthylamide hydrolysing activity in selected photoneuroendocrine areas of adult male rats.

Soluble Leu-beta-naphthylamide hydrolysing activity (arylamidase activity) was assayed in retina, superior cervical ganglia, several brain areas and serum of adult male rats, at different time points of a 12:12h light:dark cycle (from 7h to 19h light). The results demonstrated a left or right biased asymmetrical distribution of this activity depending on the time point studied: While the levels of activity were significantly higher in the left retina than in the right one at 10h of the light period, these were predominant in the right side, at 01h of the dark period. In addition, this activity was higher in the left hypothalamus at 13h of the light period. No asymmetries were disclosed in the rest of time points and structures studied. On the other hand, this activity demonstrated a diurnal variation in the left anterior hypothalamus and total posterior hypothalamus but no periodic variation was evidenced in right anterior hypothalamus or the rest of zones studied. These results may reflect the role of this activity regulating the functional status of its susceptible endogenous substrates.     

A Shared Neural Substrate for Mentalizing and the Affective Component of Sentence Comprehension

Using event-related fMRI in a sample of 42 healthy participants, we compared the cerebral activity maps obtained when classifying spoken sentences based on the mental content of the main character (belief, deception or empathy) or on the emotional tonality of the sentence (happiness, anger or sadness). To control for the effects of different syntactic constructions (such as embedded clauses in belief sentences), we subtracted from each map the BOLD activations obtained during plausibility judgments on structurally matching sentences, devoid of emotions or ToM. The obtained theory of mind (ToM) and emotional speech comprehension networks overlapped in the bilateral temporo-parietal junction, posterior cingulate cortex, right anterior temporal lobe, dorsomedial prefrontal cortex and in the left inferior frontal sulcus. These regions form a ToM network, which contributes to the emotional component of spoken sentence comprehension. Compared with the ToM task, in which the sentences were enounced on a neutral tone, the emotional sentence classification task, in which the sentences were play-acted, was associated with a greater activity in the bilateral superior temporal sulcus, in line with the presence of emotional prosody. Besides, the ventromedial prefrontal cortex was more active during emotional than ToM sentence processing. This region may link mental state representations with verbal and prosodic emotional cues. Compared with emotional sentence classification, ToM was associated with greater activity in the caudate nucleus, paracingulate cortex, and superior frontal and parietal regions, in line with behavioral data showing that ToM sentence comprehension was a more demanding task.     

Neurotrophin-3 controls proliferation of granular precursors as well as survival of mature granule neurons in the developing rat cerebellum

Levels of neurotrophin-3 markedly decrease in the rat cerebellum after the first 10 days of life, suggesting an importance during early development. To further examine the effect of neurotrophin-3 on the developing cerebellum, we injected a monoclonal antibody against neurotrophin-3 into the lateral ventricle of 7.5-day-old rats. The resultant depletion of neurotrophin-3 caused a significant decrease in cerebellar wet weights noted at 7 and 23 days thereafter. Other changes noted 48 h after injection of monoclonal antibodies against neurotrophin-3 included reduced incorporation of bromode-oxyuridine into granule neurons in the external germinal layer, an elevated density of atrophic neurons that had just migrated under the Purkinje cell layer, and an increased number of apoptotic neurons in the internal granule cell layer. These changes were limited to the central lobe. The concentration of neurotrophin-3 protein in the posterior region, including the central lobe, was about four- and threefold higher than that in the anterior region of the cerebellum of 9.5- and 30-day-old rats, respectively. Immunocytochemical examination showed higher amounts of neurotrophin-3 protein in the central lobe than in the anterior lobe. Our results provide evidence that neurotrophin-3 regulates the proliferation of granule precursors and supports the survival of mature granule neurons in restricted lobules, suggesting an involvement in limited regions at a specific stage in development of the rat cerebellum.     

Abnormal Regional Homogeneity in Patients with Essential Tremor Revealed by Resting-State Functional MRI

Essential tremor (ET) is one of the most common movement disorders in human adults. It can be characterized as a progressive neurological disorder of which the most recognizable feature is a tremor of the arms or hands that is apparent during voluntary movements such as eating and writing. The pathology of ET remains unclear. Resting-state fMRI (RS-fMRI), as a non-invasive imaging technique, was employed to investigate abnormalities of functional connectivity in ET in the brain. Regional homogeneity (ReHo) was used as a metric of RS-fMRI to assess the local functional connectivity abnormality in ET with 20 ET patients and 20 age- and gender-matched healthy controls (HC). The ET group showed decreased ReHo in the anterior and posterior bilateral cerebellar lobes, the bilateral thalamus and the insular lobe, and increased ReHo in the bilateral prefrontal and parietal cortices, the left primary motor cortex and left supplementary motor area. The abnormal ReHo value of ET patients in the bilateral anterior cerebellar lobes and the right posterior cerebellar lobe were negatively correlated with the tremor severity score, while positively correlated with that in the left primary motor cortex. These findings suggest that the abnormality in cerebello-thalamo-cortical motor pathway is involved in tremor generation and propagation, which may be related to motor-related symptoms in ET patients. Meanwhile, the abnormality in the prefrontal and parietal regions may be associated with non-motor symptoms in ET. These findings suggest that the ReHo could be utilized for investigations of functional-pathological mechanism of ET.     

Microsurgically generated discontinuities provoke heritable changes in cellular handedness of a ciliate, Stylonychia mytilus

Stylonychia mytilus is a dorsoventrally flattened ciliate with compound ciliary structures arranged in a specific manner on the cell surface. In mirror-image (MI) doublets of this ciliate, two nearly complete sets of ciliary structures are arrayed side-by-side, one in a normal or 'right-handed' (RH) arrangement, the other in a reversed or 'left-handed' (LH) arrangement. MI-doublets exist in two forms, one with the RH component on the right, the LH component on the left, and feeding structures near the center ('buccal-adjoining MI-doublet'); the other with the RH component on the left, the LH component on the right, and feeding structures on the lateral edges ('buccal-opposing MI-doublet'). We describe an operation that can generate either type of MI-doublet. This operation interchanges large anterior and posterior regions of the cell, transposing the original posterior region anteriorly (P----A) and the original anterior region posteriorly (A----P), while retaining the original anteroposterior polarity of each region. Two sets of new ciliary structures then are formed in mirror-image arrangement, with the set in the P----A region oriented normally and the set in the A----P region undergoing a reversal of polarity along its anteroposterior axis. This sometimes creates end-to-end MI forms, but more commonly produces side-by-side MI-doublets through a folding together of the P----A and A----P regions. This folding occurs because one lateral edge of the cell had been removed during the operation; if the left edge was removed, the complex folds to the left and forms a buccal-adjoining MI-doublet, whereas if the right edge was removed, the complex folds to the right and forms a buccal-opposing MI-doublet. Both types can reorganize and later divide true-to-type, although the 'buccal-opposing' type is by far the more stable of the two. The generation of mirror-image forms is dependent on the prior abnormal juxtaposition of regions from opposite ends of the cell, and involves a coordinated respecification of large-scale organization. We interpret this response to be a consequence of intercalation of missing intervening positional values in the zone of posterior-anterior abutment.     

3':5'-cyclic-nucleotide phosphodiesterase in the bovine pituitary gland

Cyclic-AMP phosphodiesterase activity in the homogenate of the anterior pituitary gland was 2-fold higher than that in the homogenate of the posterior pituitary, whereas cyclic-GMP phosphodiesterase activity was dominant in the posterior homogenate. There were two peaks of cyclic-AMP phosphodiesterase activity with different isoelectric points of 4.3 and 5.2. Fraction I had a molecular weight of 240 000 and a sedimentation coefficient of 6.2 S; fraction II had a molecular weight of 180 000 and a sedimentation coefficient of 3.1 S. Cyclic AMP hydrolytic activity in the supernatant of the posterior lobe corresponded to fraction I in the anterior lobe. Cyclic GMP hydrolytic activity in both the anterior and posterior lobes (activated by Ca2+/calmodulin) had an isoelectric point of 5.2, a molecular weight of 240 000 and a sedimentation coefficient of 6.2 S. Cyclic AMP and GMP hydrolytic activities in both the anterior and posterior lobes appeared in fraction I and did not separate when the preparations were mixed before electric focusing or sucrose density gradient procedures. Cyclic AMP hydrolytic activity in fraction II could be separated from cyclic GMP hydrolytic activity.     

Category differences in brain activation studies: where do they come from?

Differences in the neural processing of six categories of pictorial stimuli (maps, body parts, objects, animals, famous faces and colours) were investigated using positron emission tomography. Stimuli were presented either with or without the written name of the picture, thereby creating a naming condition and a reading condition. As predicted, naming increased the demands on lexical processes. This was demonstrated by activation of the left temporal lobe in a posterior region associated with name retrieval in several previous studies. This lexical effect was common to all meaningful stimuli and no category-specific effects were observed for naming relative to reading. Nevertheless, category differences were found when naming and reading were considered together. Stimuli with greater visual complexity (animals, faces and maps) enhanced activation in the left extrastriate cortex. Furthermore, map recognition, which requires greater spatio-topographical processing, also activated the right occipito-parietal and parahippocampal cortices. These effects in the visuo-spatial regions emphasize inevitable differences in the perceptual properties of pictorial stimuli. In the semantic temporal regions, famous faces and objects enhanced activation in the left antero-lateral and postero-lateral cortices, respectively. In addition, we showed that the same posterior left temporal region is also activated by body parts. We conclude that category-specific brain activations depend more on differential processing at the perceptual and semantic levels rather than at the lexical retrieval level.     

The induction of lysosomal enzyme activity in the fat body of Calliphora erythrocephala: Changes in the internal environment

The activity of the lysosomal marker enzyme acid phosphatase in the larval fat body of Calliphora erythrocephala increases during development, but not at the same rate throughout the tissue. During the feeding stage, the posterior region has a higher acid phosphatase activity than the anterior region. When the larvae cease feeding on the 5th day of development, the acid phosphatase activity of the inactive anterior lobe increases rapidly in a mosaic-cell pattern. When 4-day-old feeding stage larvae are starved, this increase occurs one day earlier than normally. After the emptying of the gut, the acid phosphatase activity of all the anterior cells both in normal and in starved larvae exceeds that of those in the posterior region.Transplantation experiments indicate that the induction of acid phosphatase activity in the fat body during normal development, especially in the anterior region, is caused by a change in the internal environment when the larvae cease feeding. Both RNA and protein synthesis are involved in this induction process. Inductive factors are present in 5-day-old larvae as well as during formation of the puparium. The competence of the feeding-stage fat cells to develop high acid phosphatase activity is acquired before the actual induction takes place.     

Changes in Oral Apparatus Structure Accompanying Vacuolar Formation in the Macrostomal Form of Tetrahymena vorax. A Model for the Formation of Food Vacuoles in Tetrahymena1

The large cytopharyngeal pouch of the macrostomal form of Tetrahymena vorax, following the addition of calcium, can form a sealed, empty vacuole. The open cytostomal region of this cell, which averages about 16 μ in diameter, is closed by an upward (ventral) movement of the right and posterior ribbed walls, both of which project into the cytostomal cavity. At the same time, the anterior and left walls of the cytostome-cytopharyngeal complex move to the right, forming a diagonally (right to left) placed furrow in the floor of the buccal cavity as these walls meet. As a result of the movement, the edges of the single membrane-bounded cytopharyngeal pouch are brought together and fuse, producing the closed vacuole. Elements of the cytoskeleton appear to participate in the closure process. Three major groups of ribbed wall microtubules support the open cytostome. The anterior ribbed wall microtubules pass laterally along the anterior (dorsal) portion of the cytopharyngeal pouch to the left where they end in the specialized cytoplasm. Middle oral rib microtubules terminate at the right and posterior margin of the cytopharynx while microtubules from the most posterior region of the ribbed wall pass to the left terminating in the specialized cytoplasm. The fine filamentous reticulum, a striated reticulum that borders the right, posterior, and anterior margins of the cytostome-cytopharyngeal complex, is in an ideal position to participate in these movements. It is anchored anteriorly high up in the buccal cavity to the cross-connective between the third membranelle and the undulating membrane complex. It courses beneath the right and posterior ribbed walls and runs laterally along the anterior margin of the cytopharynx to the left side. Contraction or pulling of this reticulum would act to bring the microtubule-reinforced walls of the cytopharynx together permitting fusion of the cytopharyngeal pouch membranes to form a sealed vacuole.     

Anterior and posterior groups of portal vessels in the avian pituitary: incidence in forty nine species.

The hypophyseal portal vessels were studied in forty nine species of birds. The primary capillary plexus in the median eminence is single or divided into an anterior and a posterior plexus. Irrespective of whether the primary capillary plexus is single or divided, distinct, non-interconnected anterior and posterior groups of portal vessels are present in all the species investigated. The anterior group of portal vessels originates in the anterior region of the median eminence and breaks up into capillaries in the cephalic lobe of the pars distalis; the posterior group of portal vessels originates in the posterior region of the median eminence and breaks up into capillaries in the caudal lobe of the pars distalis. This type of regional distribution of portal vessels appears to be of general occurrence in the avian pituitary. The median eminence in the species investigated shows an AF-positive anterior region and an AF-negative posterior region. The pars distalis is differentiated into histologically distinct cephalic and caudal lobes. The arrangement of the portal vessels into anterior and posterior groups provides morphological basis for the view that the functions of the cephalic lobe may be controlled by the anterior median eminence, whereas those of the caudal lobe may be controlled by the posterior median eminence. However, experimental data available to date do not suggest a physiological significance to the widespread incidence of the regional distribution of portal vessels in the avian pituitary.     

The zygotic mutant tailless affects the anterior and posterior ectodermal regions of the Drosophila embryo

The recessive zygotic lethal mutation tailless maps to region 100A5,6-B1,2 at the tip of the right arm of chromosome 3, and results in shortened pharyngeal ridges in the head skeleton of the mature embryo and the elimination of the eighth abdominal segment and telson. Although they have a normal body length, tailless embryos have a smaller number of abdominal segments, some of which are larger than normal. The mutant phenotype is seen as early as 8 hr postfertilization, when tailless embryos are observed to have fewer tracheal pits than wildtype. At 9 hr, tailless embryos appear to be missing segments A8, A9, and A10 and have an abnormal clypeolabrum, optic lobes, and procephalic lobe. Segments A4, A5, A6, and A7 appear larger in tailless embryos than wildtype at this stage. The tailless mutation, although affecting anterior and posterior ectodermal structures in the mature embryo, does not affect the formation of pole cells, the posterior midgut, or the proctodeum, which arise from the most posterior region of the embryo. The mutation does result, however, in the failure of Malpighian tubule formation. Consistent with its effect on ectodermal segments, tailless leads to a reduction in the number of segmented, paired ganglia in the ventral nerve cord as well as to an abrupt alteration in the posterior region of the tracheal system. The role the tailless gene may play in the formation of the most anterior and posterior regions of the embryo's ectodermal body plan is discussed.     

Anterior/Posterior Competitive Deactivation/Activation Dichotomy in the Human Hippocampus as Revealed by a 3D Navigation Task

Anterior/posterior long axis specialization is thought to underlie the organization of the hippocampus. However it remains unclear whether antagonistic mechanisms differentially modulate processing of spatial information within the hippocampus. We used fMRI and a virtual reality 3D paradigm to study encoding and retrieval of spatial memory during active visuospatial navigation, requiring positional encoding and retrieval of object landmarks during the path. Both encoding and retrieval elicited BOLD activation of the posterior most portion of hippocampus, while concurrent deactivations (recently shown to reflect decreases in neural responses) were found in the most anterior regions. Encoding elicited stronger activity in the posterior right than the left hippocampus. The former structure also showed significantly stronger activity for allocentric vs. egocentric processing during retrieval. The anterior vs. posterior pattern mimics, from a functional point, although at much distinct temporal scales, the previous anatomical findings in London taxi drivers, whereby posterior enlargement was found at the cost of an anterior decrease, and the mirror symmetric findings observed in blind people, in whom the right anterior hippocampus was found to be larger, at the cost of a smaller posterior hippocampus, as compared with sighted people. In sum, we found a functional dichotomy whereby the anterior/posterior hippocampus shows antagonistic processing patterns for spatial encoding and retrieval of 3D spatial information. To our knowledge, this is the first study reporting such a dynamical pattern in a functional study, which suggests that differential modulation of neural responses within the human hippocampus reflects distinct roles in spatial memory processing.     

Copper effects on key metabolic enzymes and mitochondrial membrane potential in gills of the estuarine crab Neohelice granulata at different salinities

The estuarine crab Neohelice granulata was exposed (96h) to a sublethal copper concentration under two different physiological conditions (hyperosmoregulating crabs: 2ppt salinity, 1mg Cu/L; isosmotic crabs: 30ppt salinity, 5mg Cu/L). After exposure, gills (anterior and posterior) were dissected and activities of enzymes involved in glycolysis (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), Krebs cycle (citrate synthase), and mitochondrial electron transport chain (cytochrome c oxidase) were analyzed. Membrane potential of mitochondria isolated from anterior and posterior gill cells was also evaluated. In anterior gills of crabs acclimated to 2ppt salinity, copper exposure inhibited hexokinase, phosphofructokinase, pyruvate kinase, and citrate synthase activity, increased lactate dehydrogenase activity, and reduced the mitochondrial membrane potential. In posterior gills, copper inhibited hexokinase and pyruvate kinase activity, and increased citrate synthase activity. In anterior gills of crabs acclimated to 30ppt salinity, copper exposure inhibited phosphofructokinase and citrate synthase activity, and increased hexokinase activity. In posterior gills, copper inhibited phosphofructokinase and pyruvate kinase activity, and increased hexokinase and lactate dehydrogenase activity. Copper did not affect cytochrome c oxidase activity in either anterior or posterior gills of crabs acclimated to 2 and 30ppt salinity. These findings indicate that exposure to a sublethal copper concentration affects the activity of enzymes involved in glycolysis and Krebs cycle, especially in anterior (respiratory) gills of hyperosmoregulating crabs. Changes observed indicate a switch from aerobic to anaerobic metabolism, characterizing a situation of functional hypoxia. In this case, reduced mitochondrial membrane potential would suggest a decrease in ATP production. Although gills of isosmotic crabs were also affected by copper exposure, changes observed suggest no impact in the overall tissue ATP production. Also, findings suggest that copper exposure would stimulate the pentose phosphate pathway to support the antioxidant system requirements. Although N. granulata is very tolerant to copper, acute exposure to this metal can disrupt the energy balance by affecting biochemical systems involved in carbohydrate metabolism.