Effect of forced exercise and exercise withdrawal on memory, serum and hippocampal corticosterone levels in rats

The time-dependent effects of physical exercise on fear memory reconsolidation and extinction in male rats

Aversive memories can enter a labile state during reactivation, allowing its content to be modified. Molecular changes induced by distinct interventions such as physical exercise can either facilitate or impair the strength of the original memory. However, the effect of the physical exercise performed at distinct time-points around memory reactivation remains poorly understood. Here we investigated how a single treadmill exercise bout delivered at different moments before or after a 5, 15 or 30-min reactivation session influences the reconsolidation and extinction of contextual fear conditioned memory in rats. Our results indicate that physical exercise of low-intensity 24 h and 10 min before the reactivation impairs reconsolidation and facilitates extinction. However, when the exercise protocol is performed immediately after the reactivation session, it facilitates reconsolidation and impairs extinction memory. Our results suggest that the specific time-point in which the physical exercise is performed plays an essential role in the reconsolidation and extinction outcome in fear conditioned animals.

Effects of physical training on the metabolic profile of rats exposed to chronic restraint stress

INTRODUCTION

Despite strong evidences supporting the protective role of exercise against stress-induced repercussions, the literature remains inconclusive regarding metabolic aspects. Therefore, this study aimed to evaluate the effect of Physical Training (PT) by swimming on the metabolic parameters of rats subjected to restraint stress.

METHODS

Wistar rats (n = 40) were divided into four groups: Control (C), Trained (T), Stressed (S), and Trained/Stressed (TS). The restraint stress protocol involved confining the animals in PVC pipes for 60 minutes/day for 12 weeks. Concurrently, the swimming PT protocol was performed without additional load in entailed sessions of 60 minutes conducted five days a week for the same duration. The following parameters were analyzed: fitness progression assessed by the physical capacity test, body mass, serum level of glucose, triglyceride, cholesterol and corticosterone, as well as glycemic tolerance test, evaluated after glucose administration (2 g/kg, i.p.).

RESULTS

Trained groups (T and TS) exhibited enhanced physical capacity (169 ± 21 and 162 ± 22% increase, respectively) compared to untrained groups (C: 9 ± 5 and S: 11 ± 13% increase). Corticosterone levels were significantly higher in the S group (335 ± 9 nmoL/L) compared to C (141 ± 3 nmoL/L), T (174 ± 3 nmoL/L) and TS (231 ± 7 nmoL/L), which did not differ from each other. There were no significant changes in serum glucose, cholesterol, and triglyceride levels among the groups. However, the glycemic curve after glucose loading revealed increased glycemia in the S group (area under curve 913 ± 30 AU) but the TS group exhibited values (673 ± 12 AU) similar to the groups C (644 ± 10 AU) and T (649 ± 9 AU).

CONCLUSION

Swimming-based training attenuated stress-induced corticosterone release and prevented glucose intolerance in rats, reinforcing the importance of exercise as a potential strategy to mitigate the pathophysiological effects of stress.

Neuroprotective effects of resistance physical exercise on the APP/PS1 mouse model of Alzheimer's disease

Introduction

Physical exercise has beneficial effects by providing neuroprotective and anti-inflammatory responses to AD. Most studies, however, have been conducted with aerobic exercises, and few have investigated the effects of other modalities that also show positive effects on AD, such as resistance exercise (RE). In addition to its benefits in developing muscle strength, balance and muscular endurance favoring improvements in the quality of life of the elderly, RE reduces amyloid load and local inflammation, promotes memory and cognitive improvements, and protects the cortex and hippocampus from the degeneration that occurs in AD. Similar to AD patients, double-transgenic APPswe/PS1dE9 (APP/PS1) mice exhibit Αβ plaques in the cortex and hippocampus, hyperlocomotion, memory deficits, and exacerbated inflammatory response. Therefore, the aim of this study was to investigate the effects of 4 weeks of RE intermittent training on the prevention and recovery from these AD-related neuropathological conditions in APP/PS1 mice.

Methods

For this purpose, 6-7-month-old male APP/PS1 transgenic mice and their littermates, negative for the mutations (CTRL), were distributed into three groups: CTRL, APP/PS1, APP/PS1+RE. RE training lasted four weeks and, at the end of the program, the animals were tested in the open field test for locomotor activity and in the object recognition test for recognition memory evaluation. The brains were collected for immunohistochemical analysis of Aβ plaques and microglia, and blood was collected for plasma corticosterone by ELISA assay.

Results

APP/PS1 transgenic sedentary mice showed increased hippocampal Aβ plaques and higher plasma corticosterone levels, as well as hyperlocomotion and reduced central crossings in the open field test, compared to APP/PS1 exercised and control animals. The intermittent program of RE was able to recover the behavioral, corticosterone and Aβ alterations to the CTRL levels. In addition, the RE protocol increased the number of microglial cells in the hippocampus of APP/PS1 mice. Despite these alterations, no memory impairment was observed in APP/PS1 mice in the novel object recognition test.

Discussion

Altogether, the present results suggest that RE plays a role in alleviating AD symptoms, and highlight the beneficial effects of RE training as a complementary treatment for AD.

Exercise after Breast Augmentation: A Randomized Controlled Trial

BACKGROUND

There are limited scientific data regarding the impact of exercise after breast augmentation surgery. Recommendations range from a few weeks to a few months of physical activity avoidance. To decide whether early exercise after breast augmentation is safe, a prospective randomized trial was designed to measure complications, scar quality, and patient-reported outcomes in this setting.

METHODS

The present study was a randomized controlled trial to investigate the effects of early exercise (1 week after surgery) on postoperative complications, scar quality, and patient-reported outcome (BREAST-Q). All women undergoing primary breast augmentation surgery in the authors' institution were randomized to either standard restrictions or exercise. The three primary outcomes measured were the presence of a complication and reoperation, scar quality, and patient-reported outcome.

RESULTS

A total of 225 participants were included in the final analysis. No differences were found among the groups for age (p = 0.66), implant size (p = 0.56), or implant pocket (p = 0.29); complication rates did not change between the control (7.5 percent) and exercise groups (6.9 percent). When assessed 12 months after surgery, the scar quality was comparable between the groups (29.9 control and 29.6 exercise, p = 0.204). Intervention groups (exercise) performed better on the BREAST-Q Augmentation Module: Satisfaction with Outcome score (66.3 control and 83.4 exercise, p < 0.01).

CONCLUSIONS

Early exercise following primary breast augmentation does not increase complication or reoperation rates or cause a reduction in scar quality after 1 year. In addition, a patient-reported outcome showed improvement in the exercise groups.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Effect of exercise intensity and duration on the levels of stress hormones and hypothalamic-pituitary-gonadal axis in adult male rats: an experimental study

PURPOSE

The effect of exercise on stress has been demonstrated in several studies which have shown that exercise intensity and duration have various effects on the reproductive axis. This study evaluated the effect of different intensities and durations of exercise on the hormonal indices of stress, such as corticosterone (CORT), norepinephrine (NEP), and also reproductive performance indices, including gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and testosterone (T).

METHODS

In this experimental study, 30 adult Wistar rats were randomly divided into five groups as follows: no-exercise, RME-1 (regular moderate exercise for 1 month), RME-6 (regular moderate exercise for 6 months), RIE-1 (regular intensive exercise for 1 month), and RIE-6 (regular intensive exercise for 6 months). At the end of the experiment, the serum levels of the abovementioned hormones and hypothalamic expression of the Gnrh gene were measured using the enzyme-linked immunosorbent assay and the real-time polymerase chain reaction method, respectively.

RESULTS

The levels of stress hormones, including CORT and NEP, increased only in the RIE-1 group compared with the no-exercise group. In addition, an increase was observed in T hormone levels in the RME-1 group compared with those in the no-exercise group, whereas LH and T hormone levels showed a greater decrease in the RIE-6 group than in the no-exercise group. Gnrh expression levels showed an increase and a decrease in the RME-1 and RIE-6 groups compared with the no-exercise group, respectively.

CONCLUSION

These results confirmed the effects of different intensities and durations of exercise on sex hormone levels.

Endurance exercise improves avoidance learning and spatial memory, through changes in genes of GABA and relaxin-3, in rats

Different exercise patterns, neurotransmitters, and some genes have numerous effects on learning and memory. This research aims to investigate the long-term effects of submaximal aerobic exercise on spatial memory (SM), passive avoidance learning (PAL), levels of serum relaxin-3, gamma-aminobutyric acid (GABA), RLN3 gene, and glutamic acid decarboxylase (GAD65/67 genes) in the brainstem of adult male Wistar rats. Fifty male Wistar rats were randomly divided into five groups: aerobic exercise groups, performed on a treadmill running (TR), for 5 weeks (Ex5, n = 10), 10 weeks (Ex10, n = 10), involuntary running wheel group for 5 weeks (IRW5, n = 10), sham (Sh, n = 10) and control (Co, n = 10). Consequently, SM, PAL, serum relaxin-3, GABA, and GAD65/67 and RLN3 genes were measured by ELISA and PCR. Ex5, Ex10 and IRW5 improved significantly SM (p ≤ 0.05), PAL (p ≤ 0.001) and decreased significantly relaxin-3 (p ≤ 0.001). RLN3 in the brain also decreased. However, it was not significant. GABA and GAD65/GAD67 increased significantly (p ≤ 0.05) in Ex5, Ex10 compared to Sh and Co. Aerobic exercise enhanced SM and PAL in Ex compared to Co and Sh. However, duration and type of exercise affected the level of enhancement. The serum relaxin-3 and RLN3 gene displayed reverse functions compared to GABA and GAD65/67 genes in Ex. Therefore, the changes of neurotransmitters in serum relaxin-3, GABA, and their genes: RLN3 and GAD65/67 respectively, influenced learning and memory meaningfully.

High intensity interval training protects from Post Traumatic Stress Disorder induced cognitive impairment

This study aimed to show the possible protective effects of high intensity interval training (HIIT) in PTSD-induced rats and probable underlying mechanisms. Female rats (n = 44) were separated as; Sedentary (SED), moderate intensity continuous training (MICT), HIIT groups. Then the groups were divided into subgroups according to PTSD induction (n = 6-8/group). Exercise groups performed HIIT or MICT for 6 weeks. On the fifth week, PTSD was induced by single prolonged stress protocol. Cognitive functions were evaluated by object recognition, anxiety levels by hole-board and elevated plus maze, and fear conditioning by passive avoidance tests. Following decapitation, malondialdehyde (MDA), glutathione (GSH), luminol and lucigenin chemiluminescence levels, and myeloperoxidase (MPO), superoxide dismutase (SOD) and catalase (CAT) activities were measured, and histopathological damage was evaluated. The data was analyzed by one-way ANOVA. Cognitive decline and aggravated anxiety levels in SED + PTSD group were improved in both PTSD-induced exercise groups (p < 0.05-0.001). The increased chemiluminescence levels, MPO activity and histological damage were depressed in both PTSD-induced exercise groups (p < 0.05-0.001). The risen MDA levels in SED + PTSD group were suppressed only in HIIT + PTSD group (p < 0.01-0.001). The decreased GSH levels were increased by MICT (p < 0.05-0.001), and CAT and SOD activities were improved via HIIT (p < 0.05). Compared to SED group, latency was decreased in SED + PTSD (p < 0.05-0.01) group. Neuronal damage scores were alleviated in both PTSD-induced exercise groups (p < 0.001). PTSD-induced memory decline was protected by both of the exercise models however more effectively by HIIT via decreasing oxidative stress, anxiety levels and by improving antioxidant capacity as a protective system for neuronal damage.

Low-Intensity Exercise in Mice Is Sufficient to Protect Retinal Function During Light-Induced Retinal Degeneration

Purpose

We previously reported that a specific treadmill running exercise regimen protects against light-induced retinal degeneration (LIRD) in mice. We hypothesized that this protective effect varies with running intensity. To test this, mice undergoing LIRD were run at different treadmill speeds and retinal function was assessed.

Methods

BALB/c mice were assigned to LIRD groups at varying treadmill speeds-0, 5, 10, or 20 m/min labeled inactive, low, medium, and high, respectively-and compared with naïve mice exposed to standard lighting (50 lux; naïve). Following 2 weeks of exercise, a subset of mice were exposed to toxic light (10,000 lux; LIRD) for 4 hours. After 5 additional days of exercise, retinal function was assessed by ERG. Corticosterone levels in serum and cathepsin B (CTSB) protein levels in muscle, brain, serum, and retina were measured. The retinal gene expression of complement factor 1qa (C1qa) and CTSB were measured.

Results

The low+LIRD and medium+LIRD exercise groups had greater a- and b-wave ERG amplitudes when compared with the inactive+LIRD group (P < 0.02). The high+LIRD mice only differed from the inactive+LIRD mice in their dark-adapted b-waves. Serum corticosterone increased in the high+LIRD mice (P < 0.006). Retinal CTSB protein levels were higher in the low+LIRD versus high+LIRD mice (P < 0.004) but were otherwise unchanged. Exercise of any intensity decreased C1qa gene expression.

Conclusions

Faster running did not additionally protect against LIRD, but it did increase serum corticosterone, suggesting stress-induced limits to exercise benefits. Unexpectedly, exercise did not increase CTSB proteins levels in muscle or serum, suggesting that it may not mediate exercise effects. Our results have implications for the use of low-intensity exercise as a vision loss treatment.

A Single Session of Aerobic Exercise Mediates Plasticity-Related Phosphorylation in both the Rat Motor Cortex and Hippocampus

A single session of aerobic exercise may offer one means to "prime" motor regions to be more receptive to the acquisition of a motor skill; however, the mechanisms whereby this priming may occur are not clear. One possible explanation may be related to the post-translational modification of plasticity-related receptors and their associated intracellular signaling molecules, given that these proteins are integral to the development of synaptic plasticity. In particular, phosphorylation governs the biophysical properties (e.g., Ca²⁺ conductance) and the migratory patterns (i.e., trafficking) of plasticity-related receptors by altering the relative density of specific receptor subunits at synapses. We hypothesized that a single session of exercise would alter the subunit phosphorylation of plasticity-related receptors (AMPA receptors, NMDA receptors) and signaling molecules (PKA, CaMKII) in a manner that would serve to prime motor cortex. Young, male Sprague-Dawley rats (n = 24) were assigned to either exercise (Moderate, Exhaustion), or non-exercising (Sedentary) groups. Immediately following a single session of treadmill exercise, whole tissue homogenates were prepared from both the motor cortex and hippocampus. We observed a robust (1.2-2.0× greater than sedentary) increase in tyrosine phosphorylation of AMPA (GluA1,2) and NMDA (GluN2A,B) receptor subunits, and a clear indication that exercise preferentially affects pPKA over pCaMKII. The changes were found, specifically, following moderate, but not maximal, acute aerobic exercise in both motor cortex and hippocampus. Given the requirement for these proteins during the early phases of plasticity induction, the possibility exists that exercise-induced priming may occur by altering the phosphorylation of plasticity-related proteins.

Sexual activity modulates neuroinflammatory responses in male rats

Immune activity influences reproduction, however, the extent to which mating experience may inversely alter immune pathways is poorly understood. A few studies in humans suggest that mating triggers a circulating immune and hypothalamic-pituitary-adrenal axis response. In male rats, mating experience enhances neuroplasticity and improves cognitive function and affective-like behavior, independent of the physical activity component. Yet, the extent to which mating experience may influence immune responses in the brain remain unexplored. Here, we hypothesized that recent mating experience in male rats increases neuroinflammatory signaling (via lipopolysaccharide [LPS] stimulation, i.p.) and associated sickness behaviors (i.e., food intake, weight loss) relative to sexually-naïve controls. Virgin male rats were exposed to a sexually non-receptive (control) or sexually-receptive female for 30 min for six consecutive days. Immediately following the last mating experience, rats were administered a saline or LPS injection and euthanized four hours later. Mating increased Tnfα responses to LPS in the brain, which positively correlated with LPS-induced weight loss. Mating also increased peripheral corticosterone among saline-treated rats, but this corticosterone response was attenuated in the most proficient copulators (e.g., shortest latencies). Thus, recent mating experience may be a unique modulator of select stimulated inflammatory signals that are relevant to adaptive neuroimmune responses and behavior.

Effect of Crocin, Exercise, and Crocin-accompanied Exercise on Learning and Memory in Rats under Chronic Unpredictable Stress

Background:

Stress affects brain functions and induces psychological disorders. Previous studies have indicated different effects of crocin and exercise on the improvement of memory in some types of stress. The present study investigated the effect of crocin, exercise, and crocin-accompanied exercise on learning, memory, and memory consolidation in rats under chronic unpredictable stress (CUS).

Materials and Methods:

Male rats were randomly allocated to different groups: control, sham, stress, stress-exercise, stress-crocin, and stress-crocin-accompanied exercise groups. The CUS and treadmill running were applied 2 h/day and 1 h/day, respectively, for 21 days. Crocin (30 mg/kg) was daily intraperitoneally injected to the rats and their behavioral variables were evaluated as a brain function using the passive avoidance test.

Results:

Results showed that the CUS significantly decreased learning and memory compared to the control group, while crocin alone and crocin-accompanied exercise significantly improved learning and memory compared to the stressed group. It was found that exercise alone caused learning but did not improve memory in unpredictable stress rats.

Conclusion:

The data indicated that unpredictable stress had very destructive effects on the brain functions. Furthermore, unlike exercise, crocin improved memory under unpredictable stress conditions. Overall, it seems that the beneficial effects of crocin-accompanied exercise on learning and memory were probably because of crocin, but not exercise.

Acute exercise inhibits gastric emptying of liquids in rats: influence of the NO-cGMP pathway

We previously found that acute exercise inhibited the gastric emptying of liquid in awake rats by causing an acid-base imbalance. In the present study, we investigated the involvement of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, vasoactive intestinal peptide (VIP), and corticotropin-releasing factor (CRF) peptide in this phenomenon. Male rats were divided into exercise or sedentary group and were subjected to a 15-min swim session against a load (2.5 or 5% b.w.). The rate of gastric emptying was evaluated after 5, 10, or 20 min postprandially. Separate groups of rats were treated with vehicle (0.9% NaCl, 0.1 mL/100 g, ip) or one of the following agents: atropine (1.0 mg/kg, ip), the NO non-selective inhibitor Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME; 10.0 mg/kg, ip), or the selective cGMP inhibitor 1H-(1,2,4)oxadiazole[4,3-a]quinoxalin-1-one (ODQ; 5.0 mg/kg, ip), the i-NOS non-specific inhibitor (aminoguanidine; 10.0 mg/kg, ip), the corticotropin-releasing factor receptor antagonist (astressin; 100 µg/kg, ip), or the vasoactive intestinal peptide (VIP) receptor antagonist Lys¹, Pro^2,5, Arg^3,4, Tyr⁶ (100 µg/kg, ip). Compared to sedentary rats, both the 2.5 and 5% exercise groups exhibited higher (P<0.05) values of blood lactate and fractional gastric dye recovery. Corticosterone and NO levels increased (P<0.05) in the 5% exercised rats. Pretreatment with astressin, VIP antagonist, atropine, L-NAME, and ODQ prevented the increase in gastric retention caused by exercise in rats. Acute exercise increased gastric retention, a phenomenon that appears to be mediated by the NO-cGMP pathway, CRF, and VIP receptors.

Effects of Crocin on Learning and Memory in Rats Under Chronic Restraint Stress with Special Focus on the Hippocampal and Frontal Cortex Corticosterone Levels

Background:

Chronic stress adversely influences brain functions while crocin, as an effective component of saffron, exhibits positive effects on memory processes. This study investigated the effects of different doses of crocin on the improvement of learning and memory as well as corticosterone (CORT) levels in the hippocampus and frontal cortex of rats subjected to chronic stress.

Materials and Methods:

Forty male rats were randomly allocated to five different groups (n = 8): Control, sham; stress (6 h/day for 21 days) groups, and two groups receiving daily intraperitoneal injections of one of two doses (30 and 60 mg/kg) of crocin accompanied by 21 days of restraint stress. Latency was evaluated as a brain function using the passive avoidance test before and one-day after a foot shock. CORT levels were measured in the homogenized hippocampus and frontal cortex.

Results:

Results revealed that chronic stress had a significantly (P < 0.01) negative effect on memory. Crocin (30 and 60 mg/kg), however, gave increase to significantly (P < 0.01 and P < 0.05; respectively) improved memory functions in the stressed rats. Furthermore, the CORT levels in the hippocampus and frontal cortex declined significantly (P < 0.05) in the stress group compared to the control. Only a crocin dose of 30 mg/kg was observed modulate significantly (P < 0.05) the CORT levels in the hippocampus and frontal cortex in the stressed group.

Conclusions:

It was found that the lower crocin dose (30 mg/kg) had more beneficial effects than its higher (60 mg/kg) dose on learning and memory under chronic stress conditions. Moreover, it was speculated that different doses of crocin act on different neurotransmitters and biochemical factors in the brain.

Sevoflurane anesthesia in pregnant rats negatively affects nerve function in offspring potentially via inhibition of the Wnt/β-catenin pathway

Due to the rapid development of medical technology used to perform intrauterine procedures during pregnancy, the number of patients receiving fetal surgery under general anesthesia is increasing. The aim of the present study was to determine the effects of anesthetics on the offspring of rats, and to identify the potential mechanisms underlying these effects. On day 14 of pregnancy, Sprague‑Dawley rats were equally divided into the following 3 groups (n=9): Control group (n=3), 3% sevoflurane group (n=3) and 4% sevoflurane group (n=3). Following birth of the offspring, the juvenile rats were assessed using an open‑field test, Morris water maze and a continuous passive avoidance test on different days to determine their learning abilities and memory. Western blot and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analyses were used to examine the expression of multiple critical factors associated with the proliferation and apoptosis of nerve cells, including Ki67, nestin, B cell leukemia/lymphoma 2 (Bcl-2), BCL2 associated X (Bax) and caspase‑3. Additionally, the level of adenosine triphosphate production among the 3 groups were compared. Furthermore, expression alterations in of glycogen synthase kinase‑3β (GSK‑3β) and β‑catenin were examined. The Morris water maze experiment revealed that an increased concentration of sevoflurane exposure significantly reduced the learning and memory abilities of the juvenile rats when compared with controls. In addition, western blotting and RT-qPCR analyses determined that the protein and mRNA expression levels of Bax, caspase‑3 and GSK‑3β were significantly increased relative to the controls. By contrast, the expression levels of nestin, Ki‑67, Bcl‑2 and β‑catenin were significantly reduced. The results of the present study suggest that exposure of pregnant mice to sevoflurane anesthesia demonstrates a negative effect on the learning and memory abilities of their offspring, and the Wnt/β-catenin signaling pathway may be involved in this process.

Effect of Physical Exercise on the Febrigenic Signaling is Modulated by Preoptic Hydrogen Sulfide Production

We tested the hypothesis that the neuromodulator hydrogen sulfide (H2S) in the preoptic area (POA) of the hypothalamus modulates the febrigenic signaling differently in sedentary and trained rats. Besides H2S production rate and protein expressions of H2S-related synthases cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (3-MPST) and cystathionine γ-lyase (CSE) in the POA, we also measured deep body temperature (Tb), circulating plasma levels of cytokines and corticosterone in an animal model of systemic inflammation. Rats run on a treadmill before receiving an intraperitoneal injection of lipopolysaccharide (LPS, 100 μg/kg) or saline. The magnitude of changes of Tb during the LPS-induced fever was found to be similar between sedentary and trained rats. In sedentary rats, H2S production was not affected by LPS. Conversely, in trained rats LPS caused a sharp increase in H2S production rate that was accompanied by an increased CBS expression profile, whereas 3-MPST and CSE expressions were kept relatively constant. Sedentary rats showed a significant LPS-induced release of cytokines (IL-1β, IL-6, and TNF-α) which was virtually abolished in the trained animals. Correlation between POA H2S and IL-6 as well as TNF-α was observed. Corticosterone levels were augmented after LPS injection in both groups. We found correlations between H2S and corticosterone, and corticosterone and IL-1β. These data are consistent with the notion that the responses to systemic inflammation are tightly regulated through adjustments in POA H2S production which may play an anti-inflammatory role downmodulating plasma cytokines levels and upregulating corticosterone release.

The Effect of Preventive, Therapeutic and Protective Exercises on Hippocampal Memory Mediators in Stressed Rats

BACKGROUND

Exercise plays a significant role in learning and memory. The present study focuses on the hippocampal corticosterone (CORT), interleukin-1 beta (IL-1β), glucose, and brain-derived neurotrophic factor (BDNF) levels in preventive, therapeutic, and protective exercises in stressful conditions.

METHODS

Forty male rats were randomly divided into four groups: the control group and the preventive, therapeutic, and protective exercise groups. The treadmill running was applied at a speed of 20-21m/min and a chronic stress of 6 hours/day for 21 days. Subsequently, the variables were measured in the hippocampus.

RESULTS

The findings revealed that the hippocampal CORT levels in the preventive exercise group had a significant enhancement compared to the control group. In the protective and particularly the therapeutic exercise groups, the hippocampal CORT levels declined. Furthermore, the hippocampal BDNF levels in the preventive and the therapeutic exercise groups indicated significantly decreased and increased, respectively, in comparison with the control group. In the preventive exercise group, however, the hippocampal glucose level turned out to be substantially higher than that in the control group.

CONCLUSION

It appears that the therapeutic exercise group had the best exercise protocols for improving the hippocampal memory mediators in the stress conditions. By contrast, the preventive exercise group could not improve these mediators that had been altered by stress. It is suggested that exercise time, compared to stress, can be considered as a crucial factor in the responsiveness of memory mediators.

Can Exercise Make You Smarter, Happier, and Have More Neurons? A Hormetic Perspective

Exercise can make you smarter, happier and have more neurons depending on the dose (intensity) of the training program. It is well recognized that exercise protocols induce both positive and negative effects depending on the intensity of the exercise, among other key factors, a process described as a hormetic-like biphasic dose-response. However, no evidences have been reported till very recently about the biphasic response of some of the potential mediators of the exercise-induced actions. This hypothesis and theory will focus on the adult hippocampal neurogenesis (AHN) as a putative physical substrate for hormesis responses to exercise in the context of exercise-induced actions on cognition and mood, and on the molecular pathways which might potentially be mediating these actions.