The neurobiological effects of senescence on dopaminergic system: A comprehensive review

Over time, the body undergoes a natural, multifactorial, and ongoing process named senescence, which induces changes at the molecular, cellular, and micro-anatomical levels in many body systems. The brain, being a highly complex organ, is particularly affected by this process, potentially impairing its numerous functions. The brain relies on chemical messengers known as neurotransmitters to function properly, with dopamine being one of the most crucial. This catecholamine is responsible for a broad range of critical roles in the central nervous system, including movement, learning, cognition, motivation, emotion, reward, hormonal release, memory consolidation, visual performance, sexual drive, modulation of circadian rhythms, and brain development. In the present review, we thoroughly examine the impact of senescence on the dopaminergic system, with a primary focus on the classic delimitations of the dopaminergic nuclei from A8 to A17. We provide in-depth information about their anatomy and function, particularly addressing how senescence affects each of these nuclei.

Unexpected appetitive events promote positive affective state in juvenile European sea bass

Some animal species exhibit considerable physiological and behavioural alterations in response to captivity. It has been hypothesized, but rarely tested, that such changes reflect a negative affective state that is associated to this specific context. In the last years, judgement bias measures have emerged as reliable indicators of animal affective state, under the assumption that individuals in a negative affective state are more likely to evaluate ambiguous stimuli as negative and display therefore pessimistic behaviours. Here, we have developed a judgement bias task for juvenile European sea bass (Dicentrarchus labrax) aiming to measure optimism/pessimism in this marine species, which have previously been reported to show important dysregulations in captive settings. Our results show that juvenile sea bass exhibit a considerable bias towards pessimistic behaviours in laboratory settings. Furthermore, juveniles that received an unexpected positive event during the judgement bias test displayed more optimistic responses toward ambiguous stimuli as compared to control fish, indicating a positive change in their affective state induced by the appetitive experience. These results reveal a direct interaction of the internal affective state with decision-making processing under ambiguity in juvenile European sea bass, highlighting therefore the potential of judgement bias tests as a tool for the advancement and improvement of our understanding of welfare in finfish aquaculture.

Development of prebiotic yogurt with addition of green-banana biomass (Musa spp.)

This study evaluated the technological viability of yogurt with the addition of green-banana biomass (Musa spp.) considering the resistant starch (BBV) as a potential prebiotic ingredient and texture agent. Four yogurt formulations were prepared: control; 3% BBV; 5% BBV; and 10% BBV. They were subjected to analysis of resistant starch, lactose, fat, total dry extract, defatted dry extract, moisture, ash, proteins, pH and titratable acidity; syneresis analysis, instrumental texture and instrumental color. All four formulations met the requirements of the identity and quality regulation for fermented milks regarding the physicochemical and microbiological parameters. In the instrumental color analysis, in all treatments with added BBV, darkening was observed after 21 days, with a reduction of a* coordinate and an increase of b* coordinate. In the instrumental texture analysis, the yogurt in the Control treatment had the highest firmness (0.430 N) at 21 days among these treatments. Among the treatments with added BBV, the yogurt with 5% added BBV showed the best results for increasing the viability of lactic bacteria. It was found that yogurt with added BBV is a promising alternative in the elaboration of functional dairy products, adding value to the banana production chain by reducing the green fruit waste.

Basal ganglia for beginners: the basic concepts you need to know and their role in movement control

The basal ganglia are a subcortical collection of interacting clusters of cell bodies, and are involved in reward, emotional, and motor circuits. Within all the brain processing necessary to carry out voluntary movement, the basal nuclei are fundamental, as they modulate the activity of the motor regions of the cortex. Despite being much studied, the motor circuit of the basal ganglia is still difficult to understand for many people at all, especially undergraduate and graduate students. This review article seeks to bring the functioning of this circuit with a simple and objective approach, exploring the functional anatomy, neurochemistry, neuronal pathways, related diseases, and interactions with other brain regions to coordinate voluntary movement.

Effect of senescence on the tyrosine hydroxylase and S100B immunoreactivity in the nigrostriatal pathway of the rat

Senescence is a natural and progressive physiological event that leads to a series of morphophysiological alterations in the organism. The brain is the most vulnerable organ to both structural and functional changes during this process. Dopamine is a key neurotransmitter for the proper functioning of the brain, directly involved in circuitries related with emotions, learning, motivation and reward. One of the main dopamine- producing nuclei is the substantia nigra pars compacta (SNpc), which establish connections with the striatum forming the so-called nigrostriatal pathway. S100B is a calcium binding protein mainly expressed by astrocytes, involved in both intracellular and extracellular processes, and whose expression is increased following injury in the nervous tissue, being a useful marker in altered status of central nervous system. The present study aimed to analyze the impact of senescence on the cells immunoreactive for tyrosine hydroxylase (TH) and S100B along the nigrostriatal pathway of the rat. Our results show an decreased expression of S100B⁺ cells in SNpc. In addition, there was a significant decrease in TH immunoreactivity in both projection fibers and TH⁺ cell bodies. In the striatum, a decrease in TH immunoreactivity was also observed, as well as an enlargement of the white matter bundles. Our findings point out that senescence is related to the anatomical and neurochemical changes observed throughout the nigrostriatal pathway.

Antifungal activity of 2-chloro-N-phenylacetamide: a new molecule with fungicidal and antibiofilm activity against fluconazole-resistant Candida spp

In the current context of emerging drug-resistant fungal pathogens such as Candida albicans and Candida parapsilosis, discovery of new antifungal agents is an urgent matter. This research aimed to evaluate the antifungal potential of 2-chloro-N-phenylacetamide against fluconazole-resistant clinical strains of C. albicans and C. parapsilosis. The antifungal activity of 2-chloro-N-phenylacetamide was evaluated in vitro by the determination of the minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), inhibition of biofilm formation and its rupture, sorbitol and ergosterol assays, and association between this molecule and common antifungal drugs, amphotericin B and fluconazole. The test product inhibited all strains of C. albicans and C. parapsilosis, with a MIC ranging from 128 to 256 µg.mL-1, and a MFC of 512-1,024 µg.mL-1. It also inhibited up to 92% of biofilm formation and rupture of up to 87% of preformed biofilm. 2-chloro-N-phenylacetamide did not promote antifungal activity through binding to cellular membrane ergosterol nor it damages the fungal cell wall. Antagonism was observed when combining this substance with amphotericin B and fluconazole. The substance exhibited significant antifungal activity by inhibiting both planktonic cells and biofilm of fluconazole-resistant strains. Its combination with other antifungals should be avoided and its mechanism of action remains to be established.

Effect of freezing on the quality of breast meat from broilers affected by White Striping myopathy

The aim of this study was to evaluate possible changes in the quality of chicken breast meat containing white stripes during freezing for 12 mo. Samples of Pectoralis major muscle from male Cobb 500 broilers containing white stripes in moderate and severe degrees were used, as well as samples from a control group (normal - absence of myopathies). Part of the samples (n = 60; n = 20 for each severity degree) were analyzed on the day of collection (beginning) and the rest (n = 240) was frozen (-20°C) for up to 12 mo. At the end of each proposed freezing period (3, 6, 9, and 12 mo), color, pH, water holding capacity, cooking loss, tenderness, lipid oxidation, chemical composition, cholesterol and collagen concentrations, myofibrillary fragmentation, and sarcomere length were analyzed. Microbiological analysis of samples was performed at the beginning and after 12 mo of freezing. Myopathy linked to freezing showed results of increased meat tenderness, with reduction of crude protein and mineral matter and increase of moisture, fat, and cholesterol, without affecting the meat's collagen percentages. However, these variations with the onset of myopathy do not compromise the consumption of broiled chicken breast meat, kept frozen for up to 12 mo.

Breast meat quality of turkey breeder hens at disposal age affected by deep pectoral myopathy

Deep pectoral myopathy (DPM) considerably affects the meat quality of commercial poultry, thus representing a challenge to the poultry industry. In this study, we examined the breast meat quality of turkey breeder hens at disposal age affected by different degrees of DPM. Samples were collected from Nicholas turkeys at disposal age (385 d), at an average weight of 12.5 kg, which were reared and slaughtered in the south region of Brazil. The breast was first classified according to the degree of DPM and then samples of the Pectoralis major were collected from birds affected (DPM degrees 2 and 3; n = 20 of each) and nonaffected (normal, absence of lesions; n = 20) by the myopathy. After the affected Pectoralis minor muscle was discarded, the carcasses were released for human consumption by the Federal Inspection Service. The meat affected by the myopathy exhibited color changes (L*, a* and b*) (P < 0.05), especially in the inner surface. Higher (P < 0.05) water-holding capacity, pH, sarcomere length and fat concentration and lower (P < 0.05) shear force and moisture percentage were observed when compared to the normal samples. From this study, can be concluded that the severe condition of deep pectoral myopathy which affects the Pectoralis minor muscle, causes variations in the quality of Pectoralis major muscle of turkey on disposal age. As a raw material, this type of meat has a higher fat content and greater capacity for retaining intracellular water, important attributes to the manufacture of processed products. In this way, the processing is an economically viable alternative to the commercialization of breast meat from birds affected by myopathy.

Season effects on the suckling behavior of piglets

The suckling behavior of piglets was evaluated in summer and winter, using 21 sows of the same genetic line. Data were collected in July (winter) and in January (summer). The experimental design was a randomized complete block (age of piglets) in a 2x2 factorial scheme, with season of the year (winter and summer) and shift (day, from 06 h to 1h:59min and night from 18h to 05h:59min) as factors. The behavioral variables analyzed were number, interval, and frequency of suckling. The behaviors were monitored on day 7 and 15 of lactation, for 24 hours. In winter, the farrowing room had a mean temperature of 20.32 ±2.17°C and a relative humidity (RH) of 58.63 ±2.99%. In the summer, the mean temperature was 26.65 ±4.02°C, with an RH of 62.22 ±12.06%. During winter, the piglets presented longer sucklings during the night, dedicating 1.84 minutes more to suckling compared to the daytime. Nighttime sucklings were 3.13 minutes longer in winter than in summer. However, in summer, piglets suckled more often during the night, with greater interval between feeds during the day. Based on our results, the season influences the suckling behavior of piglets, with shorter feedings and greater frequencies in summer.

Corticostriatal dynamics encode the refinement of specific behavioral variability during skill learning

Learning to perform a complex motor task requires the optimization of specific behavioral features to cope with task constraints. We show that when mice learn a novel motor paradigm they differentially refine specific behavioral features. Animals trained to perform progressively faster sequences of lever presses to obtain reinforcement reduced variability in sequence frequency, but increased variability in an orthogonal feature (sequence duration). Trial-to-trial variability of the activity of motor cortex and striatal projection neurons was higher early in training and subsequently decreased with learning, without changes in average firing rate. As training progressed, variability in corticostriatal activity became progressively more correlated with behavioral variability, but specifically with variability in frequency. Corticostriatal plasticity was required for the reduction in frequency variability, but not for variability in sequence duration. These data suggest that during motor learning corticostriatal dynamics encode the refinement of specific behavioral features that change the probability of obtaining outcomes.

DOI:http://dx.doi.org/10.7554/eLife.09423.001

Learning a new motor skill typically involves a degree of trial and error. Movements that achieve the desired outcome—from catching a ball to playing scales—are repeated and refined until they can be produced on demand. This process is made more difficult as the activity of individual neurons and muscle fibers can vary at random, and this reduces the ability to reproduce a given movement precisely and reliably.

It has been suggested that the motor system overcomes this problem by identifying those parts of a task that are essential for achieving the end goal, and then focusing resources on reducing the variability in the performance of those parts alone. Santos et al. now provide direct evidence in support of this proposal by recording the activity of neurons in motor regions of the mouse brain as the animals learn a lever pressing task.

By giving mice a food reward each time they pressed the lever four times in a row, Santos et al. trained the animals to press the lever in bouts. The experiment was then slightly modified, so that the mice had to perform the four lever presses more rapidly in order to earn their reward. Consistent with predictions, the average speed of lever pressing initially varied greatly, but this variability decreased as the animals learned the task. By contrast, the total duration of individual bouts of lever pressing—which depends largely on the number of times the mice press the lever—was just as variable after training as before.

A similar pattern emerged for the activity of individual motor neurons in the mouse brain. Whereas their activity initially varied greatly, this variability decreased over training. Moreover, it became increasingly linked to the variability in the speed of lever pressing, but not with the variability in the duration of individual bouts.

The work of Santos et al. has thus shown in real time how the motor system focuses its efforts on reducing variability in those specific parts of a task that are essential for achieving a goal. Without a process called corticostriatal plasticity, by which the motor system adapts, mice could not refine this variability.

DOI:http://dx.doi.org/10.7554/eLife.09423.002

Anti-inflammatory and analgesic effects of low-level laser therapy on the postoperative healing process

[Purpose] This study aimed to evaluate the anti-inflammatory and analgesic effects of intraoral application of low-level laser therapy (660 nm) to control pain, swelling and interincisal opening following the extraction of mandibular third molars. [Subjects and Methods] Ten patients underwent removal of lower third molars using the same surgical protocol and pharmacological approach. In the postoperative period, all patients received four consecutive daily sessions of low-level laser therapy, beginning 24 hours after the surgery. Intraoral applications using the diode laser with 660 nm wavelength in the continuous scan mode were performed covering the entire surgical area, which was divided into four quadrants, each of 1 cm² area at a distance of 1 cm. The energy applied at each point was 5 J/cm² during 8 seconds. [Results] The swelling and interincisal opening returned to normal 24 hours after the first low-level laser therapy application (Friedman test). Moreover, the pain intensity was reduced on the third postoperative day, according to the Friedman test. [Conclusion] Low-level laser therapy (660 nm), at the dosimetry used in this study, was effective in reducing postoperative pain and swelling following oral surgery.

Effect of low-level laser therapy on the gene expression of collagen and vascular endothelial growth factor in a culture of fibroblast cells in mice

Low-level laser therapy treatment (LLLT) is widely used in rehabilitation clinics with the aim of accelerating the process of tissue repair; however, the molecular bases of the effect of LLLT have not been fully established. The aim of the present study was to evaluate the influence of the exposure of different doses of LLLT on the expression of collagen genes type I alpha 1 (COL1α1) and vascular endothelial growth factor (VEGF) in the fibroblast cells of mice (L929) cultivated in vitro. Fibroblast cells were irradiated with a Gallium-Arsenide laser (904 nm) every 24 h for 2 consecutive days, stored in an oven at 37 °C, with 5% CO2 and divided into 3 groups: G1-control group, G2-irradiated at 2 J/cm(2), and G3-irradiated at 3 J/cm(2). After irradiation, the total RNA was extracted and used in the complementary DNA (cDNA) synthesis. The gene expression was analyzed by real-time polymerase chain reaction. The cells irradiated in G2 exhibited a statistically significant growth of 1.78 in the expression of the messenger RNA (mRNA) of the COL1α1 gene (p = 0.036) in comparison with G1 and G3. As for the VEGF gene, an increase in expression was observed in the two irradiated groups in comparison with the control group. There was an increase in expression in G2 of 2.054 and G3 of 2.562 (p = 0.037) for this gene. LLLT (904 nm) had an influence on the expression of the genes COL1α1 (2 J/cm(2)) and VEGF (2 e 3 J/cm(2)) in a culture of the fibroblast cells of mice.

The effects of social isolation on steroid hormone levels are modulated by previous social status and context in a cichlid fish

Social isolation is a major stressor which impacts the physiology, behaviour and health of individuals in gregarious species. However, depending on conditional and contextual factors, such as social status and group composition, social isolation may be perceived differently by different individuals or even by the same individuals at different times. Here we tested the effects of social status (territorial vs. non-territorial) and previous group composition (i.e. type of social group: mixed sex group with two territorial males, TT vs. mixed sex group with one territorial and one non-territorial male, TnT) on the hormonal response (androgens and cortisol) to social isolation in a cichlid fish (Oreochromis mossambicus). The different steroid hormones measured responded differentially to social isolation, and their response was modulated by social factors. Social isolation elicited a decrease of 11-keto formation only in territorial males, whereas non-territorial males present a non-significant trend for increasing KT levels. Testosterone did not respond to social isolation. Cortisol only increased in isolated individuals from TnT groups irrespective of social status (i.e. both in territorials and non-territorials). These results suggest that it is the perception of social isolation and not the objective structure of the situation that triggers the hormonal response to isolation.

Analysis of cutaneous lymphomas in a medical center in Bahia, Brazil

OBJECTIVES

To evaluate the frequency of the different types of cutaneous lymphoma (CL) in 1 university hospital in Brazil and compare this frequency with those observed in other countries.

METHODS

After review, 72 (84.7%) cases of primary cutaneous T-cell lymphoma (CTCL) and 13 (15.3%) cases of primary cutaneous B-cell lymphoma (CBCL) were included.

RESULTS

Of the CTCLs, 40.3% were mycosis fungoides (MF); 26.4% were adult T-cell leukemias/lymphomas (ATLs); 23.6% were peripheral T-cell lymphomas, unspecified; and 8.3% were anaplastic large cell lymphomas. Of the MF cases, 17.2% progressed to transformed MF. Five-year survival for primary human T-cell lymphotropic virus type 1-negative CTCL, ATL, and CBCL was 64.0%, 42.1%, and 62.5%, respectively. MF and ATL were the most frequent primary CTCLs.

CONCLUSIONS

The frequencies observed here are close to those observed in Peru but different from those of European countries. Unfortunately, the World Health Organization/European Organization of Research and Treatment of Cancer classification does not include primary cutaneous ATL.

Ecological modulation of reproductive behaviour in the peacock blenny: a mini-review

The inter-populational variation in the reproductive behaviour of the peacock blenny Salaria pavo (Risso 1810), particularly the influence of the ecologic environment, was reviewed in the present work. Two populations of this species inhabiting contrasting environments were studied: the Ria Formosa population, a coastal lagoon with sandy/muddy substrate located in the south of Portugal, and the Gulf of Trieste, an area presenting rocky substrate located in the northern Adriatic sea. The remarkable differences in the mating system and reproductive behaviour between the two populations (namely sex-role reversal and high frequency of alternative reproductive tactics (ARTs) at the Ria Formosa vs typical sex roles and low frequency of ARTs at the Gulf of Trieste) are interpreted as a plastic behavioural and physiological response to contrasting ecological conditions. Androgens, namely 11-ketotestosterone, seem to act as mediators of this response. The expression and activity of the enzyme aromatase in the brain also seems to play a key role in fine-tuning the behavioural output in all male morphs as well as females.

Social plasticity in fish: integrating mechanisms and function

Social plasticity is a ubiquitous feature of animal behaviour. Animals must adjust the expression of their social behaviour to the nuances of daily social life and to the transitions between life-history stages, and the ability to do so affects their Darwinian fitness. Here, an integrative framework is proposed for understanding the proximate mechanisms and ultimate consequences of social plasticity. According to this framework, social plasticity is achieved by rewiring or by biochemically switching nodes of the neural network underlying social behaviour in response to perceived social information. Therefore, at the molecular level, it depends on the social regulation of gene expression, so that different brain genomic and epigenetic states correspond to different behavioural responses and the switches between states are orchestrated by signalling pathways that interface the social environment and the genotype. At the evolutionary scale, social plasticity can be seen as an adaptive trait that can be under positive selection when changes in the environment outpace the rate of genetic evolutionary change. In cases when social plasticity is too costly or incomplete, behavioural consistency can emerge by directional selection that recruits gene modules corresponding to favoured behavioural states in that environment. As a result of this integrative approach, how knowledge of the proximate mechanisms underlying social plasticity is crucial to understanding its costs, limits and evolutionary consequences is shown, thereby highlighting the fact that proximate mechanisms contribute to the dynamics of selection. The role of teleosts as a premier model to study social plasticity is also highlighted, given the diversity and plasticity that this group exhibits in terms of social behaviour. Finally, the proposed integrative framework to social plasticity also illustrates how reciprocal causation analysis of biological phenomena (i.e. considering the interaction between proximate factors and evolutionary explanations) can be a more useful approach than the traditional proximate-ultimate dichotomy, according to which evolutionary processes can be understood without knowledge on proximate causes, thereby black-boxing developmental and physiological mechanisms.

Social familiarity modulates personality trait in a cichlid fish

Personality traits, such as exploration-avoidance, are expected to be adaptive in a given context (e.g. low-risk environment) but to be maladaptive in others (e.g. high-risk environment). Therefore, it is expected that personality traits are flexible and respond to environmental fluctuations, given that consistency across different contexts is maintained, so that the relative individual responses in relation to others remains the same (i.e. although the magnitude of the response varies the differences between high and low responders are kept). Here, we tested the response of male cichlid fish (Oreochromis mossambicus) to a novel object (NO) in three different social contexts: (i) social isolation, (ii) in the presence of an unfamiliar conspecific, and (iii) in the presence of a familiar conspecific. Males in the familiar treatment exhibited more exploratory behaviour and less neophobia than males in either the unfamiliar or the social isolation treatments. However, there were no overall correlations in individual behaviour across the three treatments, suggesting a lack of consistency in exploration-avoidance as measured by the NO test in this species. Moreover, there were no differences in cortisol responsiveness to an acute stressor between the three treatments. Together, these results illustrate how behavioural traits usually taken as measures of personality may exhibit significant flexibility and lack the expected consistency across different social contexts.

Subcellular location of PKA controls striatal plasticity: stochastic simulations in spiny dendrites

Dopamine release in the striatum has been implicated in various forms of reward dependent learning. Dopamine leads to production of cAMP and activation of protein kinase A (PKA), which are involved in striatal synaptic plasticity and learning. PKA and its protein targets are not diffusely located throughout the neuron, but are confined to various subcellular compartments by anchoring molecules such as A-Kinase Anchoring Proteins (AKAPs). Experiments have shown that blocking the interaction of PKA with AKAPs disrupts its subcellular location and prevents LTP in the hippocampus and striatum; however, these experiments have not revealed whether the critical function of anchoring is to locate PKA near the cAMP that activates it or near its targets, such as AMPA receptors located in the post-synaptic density. We have developed a large scale stochastic reaction-diffusion model of signaling pathways in a medium spiny projection neuron dendrite with spines, based on published biochemical measurements, to investigate this question and to evaluate whether dopamine signaling exhibits spatial specificity post-synaptically. The model was stimulated with dopamine pulses mimicking those recorded in response to reward. Simulations show that PKA colocalization with adenylate cyclase, either in the spine head or in the dendrite, leads to greater phosphorylation of DARPP-32 Thr34 and AMPA receptor GluA1 Ser845 than when PKA is anchored away from adenylate cyclase. Simulations further demonstrate that though cAMP exhibits a strong spatial gradient, diffusible DARPP-32 facilitates the spread of PKA activity, suggesting that additional inactivation mechanisms are required to produce spatial specificity of PKA activity.

The striatum is a part of the basal ganglia which plays a role in addiction and reward learning. Its importance is underscored by pathologies such as Parkinson's disease and Huntington's disease in which degeneration of the dopamine inputs to the striatum or degeneration of neurons in the striatum, respectively, produces motor dysfunction. Dopamine in the striatum activates cascades of signaling molecules, ultimately producing an activity dependent change in the strength of connections between neurons. However, the dispersive movement of signaling molecules seems incompatible with the strengthening of specific subsets of connections, which is required for formation of distinct memories. Anchoring proteins, which restrict molecules to particular compartments within the neuron, are proposed to achieve specificity. We develop a reaction-diffusion model of dopamine activated signaling pathways to explore mechanisms whereby anchoring proteins can produce specificity. We use an efficient Monte-Carlo simulator to implement the cascades of signaling molecules in a neuronal dendrite with multiple dendritic spines. Simulations demonstrate that spatial specificity requires both anchoring proteins and inactivation mechanisms that limit the diffusion of signaling molecules.

Laser 904 nm action on bone repair in rats with osteoporosis

SUMMARY

The aim of the present study was to determine the action of AsGA laser irradiation on bone repair in the tibia of osteopenic rats. The animals were randomly divided into eight experimental groups according to the presence of ovarian hormone (sham group) or the absence of the hormone (OVX group), as well as being irradiated or non-irradiated. Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.

INTRODUCTION

The development of new techniques to speed the process of bone repair has provided significant advances in the treatment of fractures. Some attention recently focused on the effects of biostimulation on bone.

METHODS

Forty-eight adult rats were randomly divided into eight experimental groups (six animals in each group) according to the presence of ovarian hormone (sham group) or absence of the hormone (ovariectomized (OVX) group) as well as being irradiated or non-irradiated. For the application of low-level laser therapy, the animals were anesthetized with one third of the dose sufficient to immobilize the animal and irradiated with AsGa laser (904 nm, 50 mJ/cm(2) for 2 s, point form and in contact). The control animals received the same type of manipulation as the irradiated animals, but with the laser turned off. Half of the animals were killed 7 days following the confection of the bone defect, and the other half were killed 21 days after the surgery. After complete demineralization, the tibias were cut cross-sectionally in the central region of the bone defect and embedded in paraffin blocks. The blocks were then cut in semi-seriated slices and stained with hematoxylin and eosin.

RESULTS

There was new bone formation in the animals in the OVX group with laser treatment killed after 7 days (p < 0.001). The lowest percentage of bone formation was observed in the OVX without laser killed after 7 days (p > 0.05). All animals killed after 21 days exhibited linear closure of the lesion.

CONCLUSION

Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.

Laser biomodulation on L 929 cell culture

OBJECTIVE

The aim of the present study was to analyze the effects of photobiomodulation using a 904-nm diode laser at two energy densities (6 J/cm(2) and 50 mJ/cm(2)) on L929 fibroblast cells.

BACKGROUND

Low-power laser irradiation (LPLI) is a non-pharmacological resource that induces important in vitro photobiomodulation on cell cultures and tissues.

METHODS

Irradiation was performed for three days at 24-h intervals. After each interval, the cells were stained with MitoTracker Orange and DioC6 dyes to assess the photobiomodulatory effects of irradiation on mitochondrial activity and changes in the endoplasmic reticulum. The MTT assay [3-(4.5-dimethylthiazol-2-yl)-2.5 diphenyltetrazolium bromide] was used to evaluate cell proliferation.

RESULTS AND CONCLUSIONS

The fluorescence microscopy assessment of mitochondria and endoplasmic reticulum in cells irradiated with 6 J/cm(2) and 50 mJ/cm(2) demonstrated intense mitochondrial activity, which was confirmed by DioC6 staining. Reticular activity was observed stemming from increased protein synthesis. Photobiomodulation with 50 mJ/cm(2) was slightly higher than with 6 J/cm(2), as demonstrated by fluorescence microscopy results. Photobiomodulation was also time-dependent, with better results 72-h after irradiation.

The role of type 4 phosphodiesterases in generating microdomains of cAMP: large scale stochastic simulations

Cyclic AMP (cAMP) and its main effector Protein Kinase A (PKA) are critical for several aspects of neuronal function including synaptic plasticity. Specificity of synaptic plasticity requires that cAMP activates PKA in a highly localized manner despite the speed with which cAMP diffuses. Two mechanisms have been proposed to produce localized elevations in cAMP, known as microdomains: impeded diffusion, and high phosphodiesterase (PDE) activity. This paper investigates the mechanism of localized cAMP signaling using a computational model of the biochemical network in the HEK293 cell, which is a subset of pathways involved in PKA-dependent synaptic plasticity. This biochemical network includes cAMP production, PKA activation, and cAMP degradation by PDE activity. The model is implemented in NeuroRD: novel, computationally efficient, stochastic reaction-diffusion software, and is constrained by intracellular cAMP dynamics that were determined experimentally by real-time imaging using an Epac-based FRET sensor (H30). The model reproduces the high concentration cAMP microdomain in the submembrane region, distinct from the lower concentration of cAMP in the cytosol. Simulations further demonstrate that generation of the cAMP microdomain requires a pool of PDE4D anchored in the cytosol and also requires PKA-mediated phosphorylation of PDE4D which increases its activity. The microdomain does not require impeded diffusion of cAMP, confirming that barriers are not required for microdomains. The simulations reported here further demonstrate the utility of the new stochastic reaction-diffusion algorithm for exploring signaling pathways in spatially complex structures such as neurons.

A computational study on the role of gap junctions and rod Ih conductance in the enhancement of the dynamic range of the retina

Recent works suggest that one of the roles of gap junctions in sensory systems is to enhance their dynamic range by avoiding early saturation in the first processing stages. In this work, we use a minimal conductance-based model of the ON rod pathways in the vertebrate retina to study the effects of electrical synaptic coupling via gap junctions among rods and among AII amacrine cells on the dynamic range of the retina. The model is also used to study the effects of the maximum conductance of rod hyperpolarization activated current I_h on the dynamic range of the retina, allowing a study of the interrelations between this intrinsic membrane parameter with those two retina connectivity characteristics. Our results show that for realistic values of I_h conductance the dynamic range is enhanced by rod-rod coupling, and that AII-AII coupling is less relevant to dynamic range amplification in comparison with receptor coupling. Furthermore, a plot of the retina output response versus input intensity for the optimal parameter configuration is well fitted by a power law with exponent . The results are consistent with predictions of more theoretical works and suggest that the earliest expression of gap junctions along the rod pathways, together with appropriate values of rod I_h conductance, has the highest impact on vertebrate retina dynamic range enhancement.

Effects of putative stressors in public aquaria on locomotor activity, metabolic rate and cortisol levels in the Mozambique tilapia Oreochromis mossambicus

Mozambique tilapia Oreochromis mossambicus were housed individually during 7 days in a continuous flow-trough respirometry system and daily exposed to one of three treatments: (1) a series of knocks on the side of the aquarium, (2) a series of photo-flashes and (3) control group. Exposure to photo-flashes did not change locomotor activity but decreased both night-time and daytime oxygen consumption throughout the experiment. Knocking induced a short-lived increase in locomotor activity and tended to increase oxygen consumption, but this latter effect was not significant. Night-time oxygen consumption was not affected by knocking exposure. Cortisol levels assayed from fish-holding water collected at the end of the experiment were significantly lower in subjects exposed to photo-flashes than in subjects exposed to knocks or controls. Males did not respond differently than females to the treatments in any of the measurements taken. In summary, the data reported here suggest that exposure to repetitive photo-flashes, but not knocking, suppressed normal energy metabolism and cortisol levels. These effects were present hours to a half day after exposure to the flashes.

The effect of nest aggregation on the reproductive behaviour of the peacock blenny Salaria pavo

The effect of nest aggregation in courtship behaviour was tested experimentally in an ecologically constrained, sex-role reversed population of the peacock blenny Salaria pavo. Mixed sex groups of eight males and eight females were tested in experimental tanks, containing eight potential nests either aggregated or dispersed. In the aggregated treatment, males spent more time inside their nests and monopolized other potential nests, causing a female-biased operational sex ratio (OSR). In the aggregated treatment, females also expressed more courtship behaviour. The results in general support the prediction that the aggregation of nests promotes male monopolization of potential nests, resulting in fewer nest-holding males and therefore a female-biased OSR that leads to the reversal of sex roles.

[Prevalence of depression among the elderly population who frequent community centers]

The objective of the study was to establish the prevalence rate of depression among the elderly population (those 60 and older) who frequent community centers. From February to July of 2001, a cross-sectional survey was conducted with elderly people from community centers in Taguatinga, Brasilia, FD (Federal District). The sample included 118 elderly people, distributed in five-year age brackets, who responded to a simplified version of the Yesavage Geriatric Depression Scale with 15 questions. Anova and the Tukey test were performed to analyze differences between the age groups with 95% confidence intervals. The sample was predominantly female (90%) with the majority reporting being in the age bracket of 60 to 64 years old (31%). Depression was reported by 36 respondents (31%) and severe depression was reported by 4% of those interviewed, all of whom were in the age bracket of 60 to 64 (representing 14% of this group). National programs should be developed in community centers focused on decreasing depression among the elderly population.

Functional groups of forest succession as dissipative structures: an applied study

This study tested the hypothesis that dissipative efficiency of tropical tree species could be an ecological advantage in the forest succession process. Daily leaf gas exchanges of a pioneer species (Guazuma ulmifolia) and a late successional species (Cariniana legalis) were evaluated under well-irrigated conditions and by withholding irrigation. Analyses of network connectance (Cg) and plant autonomy (At) were carried out in order to assess metabolic network changes in response to environmental perturbation. As a global estimation of latent heat dissipation, the capacity to both maintain and cool leaf temperature in response to air temperature changes (deltaT = T degrees Cair - T degrees Cleaf) was evaluated. The changes observed in both the systemic parameters (Cg and At) and the physiological ones brought about by water deficit, associated with discrepant growth rates between both species, suggested that the initial formation of gap canopies composed by pioneer species could simply be a result of the higher photosynthetic rates of these species, and not necessarily because late successional species cannot cope with such a heterogeneous environment as that of a gap. Our results indicate that, in the absence of water constraints, the highest CO2 assimilation rates of pioneer species are supported by the efficiency of the whole dissipative structure, involving both degradation and dissipative processes. As a practical result, our study suggests the deltaT analysis in order to evaluate the efficiency of dissipative structures and as a aid in characterizing functional groups.

The role of androgens in the trade-off between territorial and parental behavior in the Azorean rock-pool blenny, Parablennius parvicornis

Androgen hormones have been shown to facilitate competitive ability in courtship and territorial behavior, while suppressing paternal behavior. The rock-pool blenny, Parablennius parvicornis, provides an excellent model to study the proximate regulation of such a trade-off between territorial and parental behavior, because nest-holder males of this species display these behaviors simultaneously. A field study was carried out in which territorial nest holder males were either treated with long-lasting implants filled with 11-ketotestosterone (11-KT) or with control implants. Males treated with 11-KT showed a higher frequency of aggressive behavior, were more responsive to aggressive challenges, and were more persistent in aggressive behavior than control males. In addition, territories were larger in males treated with 11-KT than in controls. We found evidence for incompatibility between defense of a large territory and high levels of parental behavior. However, contrary to expectation, 11-KT did not suppress parental behavior. We suggest that trade-offs between territorial and parental behavior may not be regulated by androgen hormones but may result from a time constraint in the individual's activity budget.

Physics of psychophysics: Stevens and Weber-Fechner laws are transfer functions of excitable media

Sensory arrays made of coupled excitable elements can improve both their input sensitivity and dynamic range due to collective nonlinear wave properties. This mechanism is studied in a neural network of electrically coupled (e.g., via gap junctions) elements subject to a Poisson signal process. The network response interpolates between a Weber-Fechner logarithmic law, and a Stevens power law depending on the relative refractory period of the cell. Therefore, these nonlinear transformations of the input level could be performed in the sensory periphery simply due to a basic property: the transfer function of excitable media.

11-Ketotestosterone inhibits the alternative mating tactic in sneaker males of the peacock blenny, Salaria pavo

In the peacock blenny, Salaria pavo, a species with courtship sex-role reversal, smaller, younger males mimic the courtship behavior and the nuptial coloration of females in order to get access to nests during spawning and to parasitize egg fertilization from nest-holder males. Later in their life, sneakers transform both morphologically and behaviorally into nest-holder males. In the present paper we investigate the activational role of 11-ketotestosterone (KT), the most potent androgen in most teleost species, to promote the switch between tactics in sneaker males of S. pavo. Sneakers were implanted either with KT or with control (i.e. castor oil) silastic implants. A week after implantation they were subjected to a set of behavioral tests and morphometric measurements. KT treatment promoted the differentiation of secondary sex characters, such as the anal glands, and inhibited the expression of female courtship behavior. KT-treated sneakers also showed a trend toward less frequent display of female nuptial coloration. There was no effect of KT treatment on the expression of typical nest-holder male behavior. Finally, there was no effect of KT treatment on the number or soma size of arginine vasotocin neurons in the preoptic area, which are often associated with the expression of vertebrate sexual behavior. Thus, KT seems to play a key role in mating tactic switching by inhibiting the expression of female courtship behavior and by promoting the development of male displaying traits (e.g. anal glands). The lack of a KT effect on behavior typical of nest-holding males and vasotocinergic preoptic neurons suggests that a longer time frame or other endocrine/social signals are needed for the initiation of these traits in males that are switching tactics.

Worm load and septal fibrosis of the liver in Capillaria hepatica-infected rats

Inocula, varying from 15 to 1,000 embryonated Capillaria hepatica eggs, were administered to young adult rats by gastric tube, in an attempt to investigate the influence of worm load in the production of septal fibrosis of the liver. Low doses of 15, 30 or 50 eggs were sufficient to produce septal fibrosis, but it appeared with variable degrees of intensity and always with focal distribution. Septal fibrosis became diffuse, progressive with time, and already well developed 40 days after infection, when 100 eggs or more were administered. However, higher inocula (200, 500 and 1,000 eggs) did not intensify septal fibrosis, although the number of parasitic focal lesions proportionally augmented.

Male sexual polymorphism, alternative reproductive tactics, and androgens in combtooth blennies (pisces: blenniidae)

In species in which intense intermale competition for the access to females is present males of lower competitive ability may adopt alternative reproductive tactics (ART) to get access to mates. These ART translate in many cases into male sexual polymorphism, with individuals following distinctly different tactics. Usually two alternative male morphs can be recognized in species with ART: (1) bourgeois males that compete for access to mates invest in typically male behaviors, such as building elaborated nests or displaying ornaments; and (2) parasitic males that take advantage of the success of the bourgeois males in attracting females and attempt "sneaker" fertilizations (e.g., sneaker and satellite males). In combtooth blennies (Blenniidae) the co-occurrence of ART and male sexual polymorphism has been described for two temperate species: the peacock blenny, Salaria pavo, and the Azorean rock-pool blenny, Parablennius sanguinolentus parvicornis. Interestingly, while in the peacock blenny the alternative male morph adopts a sneaker tactic, in the rock-pool blenny parasitic males act as satellites to nest-holder males. Thus, this variation in the ART expressed in these two closely related species allows for a comparative study of the proximate and ultimate factors affecting the expression of the two ART. In this article we summarize the available information on androgen levels in bourgeois and parasitic males of natural populations of the two species and of recent studies on the effect of exogenous administration of androgens on tactic switching in parasitic males of the two species. The information is discussed within the frame of the relative plasticity hypothesis, which predicts that plastic alternative morphs should show differences in hormone levels and that the administration of sex steroids should be effective in promoting the switch from the parasitic to bourgeois tactic. The evidence is only partly consistent with this hypothesis. Alternatively, a social transduction hypothesis that better fits the available data on androgens and ART in teleost is proposed. It states that the observed differences in androgen levels between alternative morphs should not be interpreted as an organization vs activation effect of steroids, but rather as the limited vs lifelong responsiveness of the neuroendocrine axis to social regulation.

Effects of androgens on social behavior and morphology of alternative reproductive males of the Azorean rock-pool blenny

In the Azorean rock-pool blenny Parablennius sanguinolentus parvicornis two sequential reproductive tactics occur. Larger and older males establish breeding territories, while some of the smaller males become attached to nest-holder territories, acting as satellites on these territories, which they help to defend while trying parasitic fertilizations when females go in the nests to spawn. In the present paper we tested the effects of the androgens 17alpha-methyltestosterone (MT) and 11-ketotestosterone (KT) in the expression of male secondary sex characters and bourgeois behavior in satellite males. One week after satellites were implanted with Silastic tubes containing MT, KT, or castor oil (control), androgen-treated satellites had developed male secondary sex traits such as longer and wider male-type genital papilla and anal glands that secrete a sex pheromone, both traits being less expressed or absent, respectively, in satellite males. Androgen treatment had no effect on the gonadosomatic index or on the development of the testicular gland. KT treatment had a positive effect on relative liver weight. In terms of behavior, androgen-implanted individuals were less aggressive both in a mirror test and toward females when these were introduced into their tanks. MT-treated individuals spend more time inside the provided nests. Only androgen-implanted satellites managed to have the females entering their nests. When given a chance in a group tank either to try to attract females to their own nest or to act as satellites of an already established nest-holder's nest, MT-implanted males spent significantly more time in their own nest than near the nest-holder nest. These data suggest that androgens, particularly testosterone, may be involved in mating tactic switching in this species.

Endocrine correlates of male polymorphism and alternative reproductive tactics in the Azorean rock-pool blenny, Parablennius sanguinolentus parvicornis

In the Azorean rock-pool blenny male sexual polymorphism occurs. Larger and older males (M+ males) fully express male secondary sex characters (SSC), particularly an anal gland that produces a sex pheromone, whereas smaller and younger sexually active males do not express SSC (M- males). Two mating tactic types can be identified among M+ males: nest-holders that establish nests and court females and floaters that move around in the breeding area and try to achieve parasitic fertilizations and/or to take over nests. Two behavioral tactic types can also be identified within M- males: satellites that are associated with particular nests and actively participate in territorial defense (when females go inside the nest to spawn they try to enter to fertilize some of the eggs) and sneakers that do not help nest holders (when spawning occurs they also try to enter the nest to fertilize eggs). It was found that M+ males have significantly higher levels of 11-ketotestosterone (KT), but not testosterone (T), than M- males [M+ male androgen levels (mean +/- SE): total T = 11.6 +/- 3.0 ng ml(-1), total KT = 4.5 +/- 1.1 ng ml(-1); M- male androgen levels (mean +/- SE): total T = 9.6 +/- 1.0 ng ml(-1), total KT = 2.5 +/- 1.1 ng ml(-1)]. There were no differences in plasma T or KT among individuals using different mating tactics within the same male morph; that is, among M+ males, nest-holders did not differ in androgen levels from floaters [nest-holder androgen levels (mean +/- SE): total T = 12.3 +/- 4.4 ng ml(-1), total KT = 4.3 +/- 1.4 ng ml(-1); floater androgen levels (mean +/- SE): total T = 5.9 +/- 0.8 ng ml(-1), total KT = 3.4 +/- 0.3 ng ml(-1)], and among M- males, satellites did not differ in androgen levels from sneakers [satellite androgen levels (mean +/- SE): total T = 7.7 +/- 1.5 ng ml(-1), total KT = 1.3 +/- 0.3 ng ml(-1); sneaker androgen levels (mean +/- SE): total T = 8.3 +/- 1.6 ng ml(-1), total KT = 1.4 +/- 0.3 ng ml(-1)]. Thus, the observed differences appear to be correlated with the expression of different male morphotypes and not with the expression of different behavioral tactics within the morphotype. Androgen levels were not correlated with the behavior activity of nest-holders, except for a negative correlation between KT levels and parental behavior. Furthermore, nest-holder males that succeeded in having females spawn in their nests during the observation period had significantly lower KT levels than unsuccessful males. Since behavioral observations preceded blood sampling in time, it is suggested that these results indicate a negative relationship between KT and parental care, since successful males were parenting when blood samples were collected. Male SSC were better correlated with KT than with T and the use of total blood levels (i.e., free + conjugates) yielded higher correlation coefficients than when only the free fraction of each steroid was considered. Since conjugates are nonactive metabolites of the free androgen they should reflect active free steroids in a previous time. Thus, their incorporation into the hormonal measurements increases the time frame captured, and because steroids are released in a pulsatile way, this time-integrated measure can be more meaningful than the free steroids, which represent a snapshot of the hormone levels at a given point in time.

Using video playbacks to study visual communication in a marine fish, Salaria pavo

Video playbacks have been successfully applied to the study of visual communication in several groups of animals. However, this technique is controversial as video monitors are designed with the human visual system in mind. Differences between the visual capabilities of humans and other animals will lead to perceptually different interpretations of video images. We simultaneously presented males and females of the peacock blenny, Salaria pavo, with a live conspecific male and an online video image of the same individual. Video images failed to elicit appropriate responses. Males were aggressive towards the live male but not towards video images of the same male. Similarly, females courted only the live male and spent more time near this stimulus. In contrast, females of the gynogenetic poecilid Poecilia formosa showed an equal preference for a live and video image of a P. mexicana male, suggesting a response to live animals as strong as to video images. We discuss differences between the species that may explain their opposite reaction to video images. Copyright 2000 The Association for the Study of Animal Behaviour.

Functions of mudballing behaviour in the European fiddler crab Uca tangeri

European fiddler crabs place mudballs around their burrow openings. Both males and females placed mudballs, but there were major differences between the sexes in mudballing behaviour, suggesting that the female's mudballs were a by-product of digging out the burrow whereas the male's may have additional functions. When the male's mudballs were removed experimentally, the number and intensity of male-male agonistic interactions increased significantly. Experimentally visually isolated males spent longer making mudballs and less time waving. In a binary choice test, females were more likely to approach dummy males with mudballs, spent longer near these males and were more likely to enter their burrows than dummy males without mudballs. The same pattern was apparent for males with 30 rather than 20 mudballs. These results are consistent with a dual function for mudballs in U. tangeri: to reduce the number and intensity of aggressive interactions between neighbouring males and to attract females. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Social modulation of sex steroid concentrations in the urine of male cichlid fish Oreochromis mossambicus

The relationship between urinary concentrations (free + sulfates + glucuronides) of the steroids testosterone (T), 11-ketotestosterone (11KT), 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17, 20 beta-P) and 17 alpha, 20 alpha-dihydroxy-4-pregnen-3-one (17, 20 alpha-P), and the social behavior of males of the cichlid fish Oreochromis mossambicus was investigated. After 8 days of isolation none of the steroids were good predictors of social dominance developed after subsequent formation of all-male groups. One day after group formation dominance indexes were good predictors of the urine concentrations of all sex steroids. Dominance indexes and androgen concentrations measured after all-male group formation were positively correlated with territoriality, courtship rate, and nest size. Similar relationships were found for progestins with the exception that they were not correlated with courtship rate. All-male group formation was also accompanied by an increase in urinary sex steroid concentrations in fish that became territorial and a decrease in non-territorial fish with the exception of T, which increased in both groups. Addition of ovulating females caused steroid concentrations to return to levels near isolation, except for 17, 20 alpha-P in territorials, which underwent a large increase. Thus, social interactions may have an important modulatory effect on sex steroid concentrations in O. mossambicus.