Unraveling the Influence of Litter Size, Maternal Care, Exercise, and Aging on Neurobehavioral Plasticity and Dentate Gyrus Microglia Dynamics in Male Rats.

This study explores the multifaceted influence of litter size, maternal care, exercise, and aging on rats' neurobehavioral plasticity and dentate gyrus microglia dynamics. Body weight evolution revealed a progressive increase until maturity, followed by a decline during aging, with larger litters exhibiting lower weights initially. Notably, exercised rats from smaller litters displayed higher body weights during the mature and aged stages. The dentate gyrus volumes showed no significant differences among groups, except for aged sedentary rats from smaller litters, which exhibited a reduction. Maternal care varied significantly based on litter size, with large litter dams showing lower frequencies of caregiving behaviors. Behavioral assays highlighted the detrimental impact of a sedentary lifestyle and reduced maternal care/large litters on spatial memory, mitigated by exercise in aged rats from smaller litters. The microglial dynamics in the layers of dentate gyrus revealed age-related changes modulated by litter size and exercise. Exercise interventions mitigated microgliosis associated with aging, particularly in aged rats. These findings underscore the complex interplay between early-life experiences, exercise, microglial dynamics, and neurobehavioral outcomes during aging.

Lactation in large litters influences anxiety, memory, and spreading depression in adult male rats that were chronically subjected to a non-convulsive pilocarpine dose.

Objectives: Unfavorable lactation influences brain excitability and behavioral reactions in adults. Administration early in life of the cholinergic agonist, pilocarpine, even at non-convulsive doses, alters the brain excitability-related phenomenon known as cortical spreading depression (CSD), and produce anxiogenic-like behavior. However, the influence of unfavorable lactation on the CSD- and memory-effects of pilocarpine administration late in life has not been investigated. Herein, we analyzed the ponderal, electrophysiological (CSD), and behavioral effects of chronic treatment with a non-convulsive dose of pilocarpine, in adult rats suckled under favorable and unfavorable conditions.Methods: Wistar rats were suckled in litters with 9 or 15 pups (groups L9 and L15, respectively). A very low dose of pilocarpine (45/mg/kg/day) was chronically administered in mature rats from postnatal day (PND) 69-90. Behavioral tests occurred at PND91 [elevated plus maze (EPM)], PND93 [open field (OF)], and PND94-95 [object recognition memory (ORM)]. CSD was recorded between PND96-120.Results: Pilocarpine-treated rats performed worse in the anxiety and memory tests, and displayed lower CSD propagation velocity when compared with saline-treated controls. In addition, L15 rats showed an increase in the distance traveled and a decrease in the immobility time in the EPM, impaired ORM, and accelerated CSD propagation when compared with L9 rats (p ≤ 0.05).Discussion: These data suggest that sub-convulsive pilocarpine treatment in adult rats can affect behavioral and excitability-related reactions. In addition, unfavorable lactation increases the ambulatory effects of pilocarpine. Further studies should investigate the possible cholinergic molecular mechanisms involved in these effects.

Undernutrition - thirty years of the Regional Basic Diet: the legacy of Naíde Teodósio in different fields of knowledge.

Undernutrition is characterized by an imbalance of essential nutrients with an insufficient nutritional intake, a disorder in which the clinical manifestations in most cases are the result of the economic and social context in which the individual lives. In 1990, the study by the medical and humanitarian Naíde Teodósio (1915-2005) and coworkers, which formulated the Regional Basic Diet (RBD) model for inducing undernutrition, was published. This diet model took its origin from the observation of the dietary habits of families that inhabited impoverished areas from the Pernambuco State. RBD mimics an undernutrition framework that extends not only to the Brazilian population, but to populations in different regions worldwide. The studies based on RBD-induced deficiencies provide a better understanding of the impact of undernutrition on the pathophysiological mechanisms underlying the most diverse prevalent diseases. Indexed papers that are analyzed in this review focus on the importance of using RBD in different areas of knowledge. These papers reflect a new paradigm in translational medicine: they show how the study of pathology using the RBD model in animals over the past 30 years has and still can help scientists today, shedding light on the mechanisms of prevalent diseases that affect impoverished populations.

Chlorella vulgaris functional alcoholic beverage: Effect on propagation of cortical spreading depression and functional properties.

Recent advances in microalgae biotechnology have proven that these microorganisms contain a number of bioactive molecules, that can be used as food additives that help prevent disease. The green microalga Chlorella vulgaris presents several biomolecules, such as lutein and astaxanthin, with antioxidant capacity, which can play a protective role in tissues. In this study, we produced and analyzed a C. vulgaris functional alcoholic beverage (produced using a traditional Brazilian alcoholic beverage, cachaça, and C. vulgaris biomass). Assays were conducted in vitro by radical scavenging tests, and in vivo, by modeling cortical spreading depression in rat brains. Scavenging radical assays showed that consumption of the C. vulgaris alcoholic beverage had a DPPH inhibition of 77.2%. This functional alcoholic beverage at a concentration of 12.5 g L-1 significantly improved cortical spreading depression velocity in the rat brains (2.89 mm min-1), when compared with cachaça alone (3.68 mm min-1) and control (distilled water; 3.25 mm min-1). Moreover, animals that consumed the functional beverage gained less weight than those that consumed just alcohol and the control groups. These findings suggest that the C. vulgaris functional alcoholic beverage plays a protective physiologic role in protecting brain cells from the effects of drinking ethanol.

Stereological Analysis of Early Gene Expression Using Egr-1 Immunolabeling After Spreading Depression in the Rat Somatosensory Cortex.

Early growth response-1 (Egr-1), defined as a zinc finger transcription factor, is an upstream master switch of the inflammatory response, and its expression can be used to investigate the spatial and temporal extent of inflammatory changes in the brain. Cortical spreading depression (CSD) is characterized as a slowly propagating (2-5 mm/min) depolarization wave through neurons and astrocytes in humans that contributes to migraines and possibly to other brain pathologies. In rodents, CSD can be induced experimentally, which involves unilateral depolarization that is associated with microglial and astrocyte responses. The impact of CSD on structures beyond the affected hemisphere has not been explored. Here, we used an optical fractionator method to investigate potential correlations between the number of and period of the eletrophysiologic record of CSD phenomena and Egr-1 expression in ipsilateral and contralateral hemispheres. CSD was elicited by the restricted application of a 2% KCl solution over the left premotor cortex. Electrophysiological events were recorded using a pair of Ag/AgCl agar-Ringer electrodes for 2 or 6 h. An optical fractionator was applied to count the Egr-1 positive cells. We found that CSD increased Egr-1 expression in a time- and event-dependent manner in the ipsilateral/left hemisphere. Although CSD did not cross the midline, multiple CSD inductions were associated with an increased number of Egr-1 positive cells in the contralateral/right hemisphere. Thus, repeated CSD waves may have far reaching effects that are more global than previously considered possible. The mechanism of contralateral expression is unknown, but we speculate that callosal projections from the depolarized hemisphere may be related to this phenomenon.

Long lasting behavioral and electrophysiological action of early administration of guanosine: Analysis in the adult rat brain.

Guanosine (GUO) is a guanine-based purine that has been extensively described in the literature as an endogenous nucleoside with participation in brain cell signalling pathways. Here, we evaluated whether chronic treatment with exogenous guanosine during brain development altered behavioral and electrophysiological parameters in adulthood. Rat pups received a daily intraperitoneal injection of 10, 50 or 100 mg/ kg/day GUO, or saline solution or no treatment (naive group) from postnatal (P) day 7 to P27. At P 60-65 the animals were behaviorally tested in the Elevated Plus-Maze (EPM). On P90-100, the electrophysiological phenomenon known as cortical spreading depression (CSD) was recorded on the right cortical surface for 4 h. With the EPM task, GUO treatment was associated with a significant increase in rearing behavior and a non-significant trend towards anxiogenic behavior. In a dose-dependent manner, GUO significantly (p < 0.01) increased weight gain on P90, and reduced the CSD propagation velocity from 3.42 ±â€¯0.10 and 3.43 ±â€¯0.10 mm/min in the Naive and Vehicle controls, respectively, to 3.05 ±â€¯0.12 mm/min, 2.87 ±â€¯0.07 mm/min and 2.25 ±â€¯0.25 mm/min in the groups treated with 10, 50 and 100 mg/kg/d GUO, respectively. The results confirmed the hypothesis that the chronic treatment with GUO early in life modulates CSD and body weight. Data on CSD propagation suggest that, besides its suppressing action on glutamatergic transmission (via enhancement of astrocytic glutamate uptake), GUO might act as an antioxidant in the brain, a hypothesis that deserves further exploration.

Brain Aging and Electrophysiological Signaling: Revisiting the Spreading Depression Model.

As a consequence of worldwide improvement in health care, the aging portion of the human population has increased, now representing a higher proportion of the total population. This fact raises great concern regarding how to age while maintaining good brain function. Very often, alterations in brain electrophysiological signaling are associated with age-dependent functional disorders of the brain. Therefore, animal models suitable for the study of age-related changes in electrical activity of the brain can be very useful. Herein, we review changes in brain electrophysiological features as a function of age by analyzing studies in the rat brain on the phenomenon known as cortical spreading depression (CSD). Alterations in the brain's capability to generate and propagate CSD may be related to differences in the propensity to develop certain neurological diseases, such as epilepsy, stroke, and migraine, which can biunivocally interact with the aging process. In this review, we revisit ours and others' previous studies on electrophysiological features of the CSD phenomenon, such as its velocity of propagation and amplitude and duration of its slow negative DC shift, as a function of the animal age, as well as the interaction between age and other factors, such as ethanol consumption, physical exercise, and nutritional status. In addition, we discuss one relatively new feature through which CSD modulates brain signaling: the ability to potentiate the brain's spontaneous electrical activity. We conclude that the CSD model might importantly contribute to a better understanding of the aging/brain signaling relationship.

Behavioral and electrophysiological brain effects of aspartame on well-nourished and malnourished rats.

The non-caloric sweetener aspartame can be potentially harmful to the developing brain, as some studies suggest an association between aspartame intake and adverse neural effects. This study aimed to evaluate the possible effects of aspartame, with or without associated early nutritional deficiency, on behavioral parameters suggestive of anxiety and electrophysiological features of the excitability-related phenomenon known as cortical spreading depression (CSD). Newborn Wistar rats (n = 80) were suckled under favorable (L9; n = 40) or unfavorable lactation conditions (L15; n = 40), consisting of litters with 9 or 15 pups, respectively. In each lactation condition, animals were divided into 4 groups that received per gavage, from postnatal day 8 to 28, 75 mg/kg/d or 125 mg/kg/d aspartame (groups ASP75 and ASP125), or water (vehicle group), or no treatment (naive group). Behavioral tests (elevated plus-maze [EPM]) were performed at postnatal days 86-95 and CSD was recorded between postnatal days 96-115. Compared to the control groups, aspartame dose-dependently reduced body weight, suggesting a negative impact on animal development; aspartame also caused behavioral changes suggestive of anxiety (shorter stay in the open arms in the EPM) and decelerated CSD (lower propagation speed). Some of these parameters were more affected in L15 animals, suggesting an interaction among aspartame and lactation condition. We concluded that early consumption of aspartame adversely affects development of the organism (weight loss), with actions on behavioral (anxiety-like) and cerebral electrophysiological (CSD) parameters. The data suggest caution in aspartame consumption by lactating mothers and their infants.

Evidence of an inverse correlation between serotonergic activity and spreading depression propagation in the rat cortex.

Various neurological and psychiatric diseases lead to alterations in cortical serotonergic activity as one of their underlying processes. However, the electrophysiological implication of changes in serotonergic activity remains a matter of investigation. In this study, we investigated whether brain serotonergic activity influences the excitability-related phenomenon known as cortical spreading depression (CSD). CSD parameters (propagation velocity, and amplitude and duration of the DC-shift) was evaluated in rats that received two treatments that increased cortical serotonergic activity, electrical stimulation of the raphe nuclei and subcutaneous injection of a selective serotonin reuptake inhibitor, sumatriptan. A third group of rats was tested on a low-tryptophan diet rat model of serotonin depletion. Control rats for these three groups received, respectively, sham raphe stimulation, saline injection, and a tryptophan-supplemented diet. Compared to controls, electrical stimulation of the raphe nuclei and sumatriptan administration decelerated CSD and increased the duration of the negative DC-shift of CSD, whereas the low-tryptophan diet was associated with significantly accelerated CSD propagation and shortened DC-shift of CSD (p<0.05). We concluded that serotonergic neurons are very important for stabilizing the delicate equilibrium between excitatory and inhibitory neuronal influences that determines cortical excitability and CSD propagation. Our pharmacological, electrophysiological and dietary data suggest that cortical serotonergic activity negatively modulates CSD propagation in the rat cortex. Reduced central serotonergic activity, as can be observed in several neurological and psychiatric diseases, may constitute a pathological factor for increased sensitivity to CSD.

Alpha-Tocopherol Counteracts the Effect of Ethanol on Cortical Spreading Depression in Rats of Various Ages, With and Without Ethanol Abstinence.

BACKGROUND: We previously demonstrated that acute and chronic treatment with ethanol (EtOH), respectively, decelerated and accelerated the propagation of cortical spreading depression (CSD) in rats and that the antioxidant carotenoid astaxanthin counteracted these effects. Here, we investigated whether noncarotenoid antioxidants exert the same action by testing α-tocopherol in rats of various ages, with and without 5 to 10 days of EtOH abstinence. METHODS: Male Wistar young adult (60 to 80 days old) and mature adult (150 to 180 days old) rats received per gavage acute (1 day) or chronic (21 days) treatment with 3 g/kg/d EtOH combined with acute (300 mg/kg) or chronic (85 mg/kg/d) treatment with α-tocopherol or vehicle-only treatment (olive oil and water for α-tocopherol and EtOH, respectively). CSD was recorded over 4 hours and the velocity of CSD propagation was calculated. On both ages, animals under chronic EtOH treatment were subjected to CSD recording immediately after EtOH treatment or after a 5- to 10-day period of EtOH abstinence. RESULTS: In both age groups, acute and chronic EtOH exposure decelerated and accelerated CSD, respectively, versus the corresponding control groups. Addition of α-tocopherol counteracted the effects of EtOH on CSD, returning CSD velocities to levels in control groups (p < 0.05). Chronic α-tocopherol (85 mg/kg/d) did not alter CSD. CONCLUSIONS: Our data reinforce the counteracting role of antioxidants on brain processes involved in the action of EtOH on CSD and suggest that this role is not a particular property of carotenoids; furthermore, this general feature of antioxidants is not substantially influenced by age or by 5 to 10 days of EtOH abstinence.

The use of cortical spreading depression for studying the brain actions of antioxidants.

OBJECTIVES: We review the main adverse effects of reactive oxygen species (ROS) in the mammalian organism, introducing the reader on the worldwide problem of the ROS neurophysiological impact on the developing and the adult brain, and discussing the neuroprotective action of antioxidant molecules. METHODS: We briefly present the electrophysiological phenomenon designated as 'cortical spreading depression' (CSD), as a parameter of normal brain functioning. We highlight recent electrophysiological advances obtained in experimental studies from our laboratory and from others, showing how to investigate the ROS effects on the brain by using the CSD phenomenon. RESULTS: Under conditions such as aging, ROS production by photo-activation of dye molecules and ethanol consumption, we describe the effects, on CSD, of treating animals with (1) antioxidants and (2) with antioxidant-deficient diets. DISCUSSION: The current understanding of how ROS affect brain electrophysiological activity and the possible interaction between these ROS effects and those effects of altered nutritional status of the organism are discussed.

The impairing effect of acute ethanol on spreading depression is antagonized by astaxanthin in rats of 2 young-adult ages.

BACKGROUND: Ethanol (EtOH) abuse and insufficient ingestion of antioxidants are external factors that can alter brain electrophysiology. Our previous studies have demonstrated that the excitability-related brain electrophysiological phenomenon known as cortical spreading depression (CSD) was facilitated by chronic EtOH intake, and chronic treatment with carotenoids attenuated this effect. Here, we investigated the acute effect of a single EtOH administration on CSD in young and adult rats previously (1 hour) treated with 10 µg/kg of astaxanthin. METHODS: Male Wistar rats (5 young- and 5 adult groups, 60 to 80 and 150 to 180 days of age, respectively) were treated by 2 gavage procedures at 1-hour interval as follows: groups 1 and 2 received astaxanthin in gavage I combined with EtOH (group 1) or water (group 2) in gavage II; groups 3 and 4 received olive oil (the vehicle in which astaxanthin was dissolved) in gavage I combined with EtOH (group 3) or water (group 4) in gavage II; group 5 received water in gavage I combined with EtOH in gavage II. CSD was recorded on the cortical surface for 4 hours. RESULTS: Compared to the respective water and oil controls (groups 2 and 4; CSD velocities: 3.73 ± 0.09 and 3.78 ± 0.07 mm/min in the young groups; 2.99 ± 0.10 and 3.05 ± 0.19 mm/min in the adult groups), a single dose of EtOH (groups 3 and 5) decreased CSD propagation velocities (3.29 ± 0.23 and 3.16 ± 0.10 mm/min in the young groups; 2.71 ± 0.27 and 2.75 ± 0.31 mm/min in the adult groups). Astaxanthin antagonized the impairing effect of acute EtOH on CSD (group 1; mean velocity: 3.70 ± 0.19 and 3.13 ± 0.16 mm/min for the young and adult groups, respectively). CONCLUSIONS: The results showed an antagonistic effect of acute EtOH treatment on CSD propagation that was reverted by astaxanthin. The EtOH-astaxanthin interaction was not influenced by the age, as it was found in both young and adult animals.

Dose-dependent effects of astaxanthin on cortical spreading depression in chronically ethanol-treated adult rats.

BACKGROUND: The consumption of alcoholic drinks is a frequent drug-abuse situation, which is associated to a wide variety of pathological disturbances affecting several organs, including the brain. We have previously shown in the developing rat brain that ethanol intake facilitates the propagation of cortical spreading depression (CSD), an excitability-related neural phenomenon present in several animal species. This electrophysiological effect was attenuated by a shrimp (Litopenaeus vannamei) carotenoids extract. Here we investigated the effects of pure astaxanthin, the main carotenoid found in shrimp, on CSD. METHODS: Adult Wistar rats were treated per gavage, during 18 days, with 2.5, 10 or 90 microg/kg/d astaxanthin dissolved in ethanol (3 g/kg) and CSD was recorded on the cortical surface 1 to 3 days thereafter. Four groups, treated respectively with ethanol, distilled water and soybean oil with- and without astaxanthin were also studied for comparison with the ethanol + astaxanthin groups. RESULTS: Ethanol-treated rats displayed higher CSD-velocities (mean values, in mm/min, per hour of recording ranging from 4.08 +/- 0.09 to 4.12 +/- 0.16), compared to the distilled water-group (from 3.19 +/- 0.13 to 3.27 +/- 0.06). Addition of astaxanthin to ethanol lead to lower CSD-velocities in a dose-dependent manner, ranging from 3.68 +/- 0.09 to 3.97 +/- 0.22 for the 2.5 microg/kg/d-dose, from 3.29 +/- 0.09 to 3.32 +/- 0.07 for the 10 microg/kg/d-dose, and from 2.89 +/- 0.13 to 2.92 +/- 0.11 for the 90 microg/kg/d-dose. The velocities of the soybean oil groups (with and without astaxanthin) were not statistically different from the 10 microg/kg/d astaxanthin + ethanol and distilled water groups. CONCLUSION: The results demonstrate the antagonistic effect of astaxanthin against the ethanol-induced facilitation of CSD propagation. Probably carotenoid antioxidant properties are involved in such effects.

Shrimp carotenoids protect the developing rat cerebral cortex against the effects of ethanol on cortical spreading depression.

Cortical spreading depression is a neural phenomenon present in several animal species. Spreading depression features, like velocity of propagation, depends on several chemical and metabolic factors, as for example, anti-oxidants. Here we studied spreading depression-velocity changes in weaned rat-pups born from dams treated on a daily basis, either during gestation or lactation, with a carotenoid ethanolic extract (30 microg/kg/day) prepared from shrimp waste (heads). These pups were compared with age-mated ones, whose mothers were treated either with the vehicle (ethanol) or with distilled water. Compared to the distilled water-group (mean values, in mm/min, per hour of recording ranging from 3.02+/-0.26 to 3.15+/-0.27 [treatment during gestation; n=7], and from 3.03+/-0.25 to 3.22+/-0.30 [lactation; n=11]), ethanol-treated rats displayed higher spreading depression-velocities (from 3.74+/-0.06 to 3.82+/-0.08 [gestation; n=7], and from 4.26+/-0.32 to 4.33+/-0.34 [lactation; n=11]; p<0.05). Compared to the ethanol-group, carotenoid-treatment lead to lower spreading depression-velocities (p<0.05), ranging from 3.38+/-0.09 to 3.42+/-0.12, n=7 (gestation) and 3.58+/-0.13 to 3.62+/-0.17, n=12 (lactation). Carotenoid-treatment during lactation was shown to be significantly more effective than that during gestation (p<0.05), in lowering spreading depression-velocity. The results suggest a protective action of shrimp carotenoids against the ethanol effects on spreading depression. This protective effect could be related to the carotenoid antioxidant properties, as previously indicated by evidence showing spreading depression-effects of other antioxidants.