Brain activation patterns at exhaustion in rats that differ in inherent exercise capacity.

In order to further understand the genetic basis for variation in inherent (untrained) exercise capacity, we examined the brains of 32 male rats selectively bred for high or low running capacity (HCR and LCR, respectively). The aim was to characterize the activation patterns of brain regions potentially involved in differences in inherent running capacity between HCR and LCR. Using quantitative in situ hybridization techniques, we measured messenger ribonuclease (mRNA) levels of c-Fos, a marker of neuronal activation, in the brains of HCR and LCR rats after a single bout of acute treadmill running (7.

Long-term voluntary wheel running is rewarding and produces plasticity in the mesolimbic reward pathway.

The mesolimbic reward pathway is implicated in stress-related psychiatric disorders and is a potential target of plasticity underlying the stress resistance produced by repeated voluntary exercise. It is unknown, however, whether rats find long-term access to running wheels rewarding, or if repeated voluntary exercise reward produces plastic changes in mesolimbic reward neurocircuitry. In the current studies, young adult, male Fischer 344 rats allowed voluntary access to running wheels for 6 weeks, but not 2 weeks, found wheel running rewarding, as measured by conditioned place preference (CPP).

A behavioral analysis of the impact of voluntary physical activity on hippocampus-dependent contextual conditioning.

Voluntary physical activity induces molecular changes in the hippocampus consistent with improved hippocampal function, but few studies have explored the effects of wheel running on specific hippocampal-dependent learning and memory processes. The current studies investigated the impact of voluntary wheel running on learning and memory for context and extinction using contextual fear conditioning which is known to be dependent on the hippocampus. When conditioning occurred prior to the start of 6 weeks of wheel running, wheel running had no effect on memory for context or extinction (assessed with freezing).

Role of central beta-adrenergic receptors in regulating proinflammatory cytokine responses to a peripheral bacterial challenge.

Elevation of proinflammatory cytokines in the brain have potent effects on altering physiological, behavioral, and cognitive processes. The mechanism(s) by which brain cytokines are induced during a peripheral immune challenge remains unclear since microorganisms/cytokines do not cross the blood-brain barrier (BBB). Recent studies indicate that central beta-adrenergic receptors (beta-ADRs) may mediate brain interleukin-1beta (IL-1) production.

Neuroplasticity of dopamine circuits after exercise: implications for central fatigue.

Habitual exercise increases plasticity in a variety of neurotransmitter systems. The current review focuses on the effects of habitual physical activity on monoamine dopamine (DA) neurotransmission and the potential implication of these changes to exercise-induced fatigue. Although it is clear that peripheral adaptations in muscle and energy substrate utilization contribute to this effect, more recently it has been suggested that central nervous system pathways "upstream" of the motor cortex, which initiate activation of skeletal muscles, are also important.

Elevated central monoamine receptor mRNA in rats bred for high endurance capacity: implications for central fatigue.

Although alteration to peripheral systems at the skeletal muscle level can contribute to one's ability to sustain endurance capacity, neural circuits regulating fatigue may also play a critical role. Previous studies demonstrated that increasing brain serotonin (5-HT) release is sufficient to hasten the onset of exercise-induced fatigue, while manipulations that increase brain dopamine (DA) release can delay the onset of fatigue. These results suggest that individual differences in endurance capacity could be due to factors capable of influencing the activity of 5-HT and DA systems.

Wheel running alters serotonin (5-HT) transporter, 5-HT1A, 5-HT1B, and alpha 1b-adrenergic receptor mRNA in the rat raphe nuclei.

Background: Altered serotonergic (5-HT) neurotransmission is implicated in the antidepressant and anxiolytic properties of physical activity. In the current study, we investigated whether physical activity alters factors involved in the regulation of central 5-HT neural activity.

Methods: In situ hybridization was used to quantify levels of 5-HT transporter (5-HTT), 5-HT(1A), 5-HT(1B), and alpha(1b)-adrenergic receptor (alpha(1b) ADR) messenger ribonucleic acids (mRNAs) in the dorsal (DRN) and median raphe (MR) nuclei of male Fischer rats after either sedentary housing or 3 days, 3 weeks, or 6 weeks of wheel running.

The consequences of uncontrollable stress are sensitive to duration of prior wheel running.

The behavioral consequences of uncontrollable stress, or learned helplessness (LH) behaviors, are thought to involve hyperactivity of serotonergic (5-HT) neurons in the dorsal raphe nucleus (DRN). Other brain regions implicated in LH and capable of affecting 5-HT systems, such as the bed nucleus of the stria terminalis (BNST), amygdala, and habenula, could contribute to DRN 5-HT hyperactivity during uncontrollable stress. Six weeks of wheel running prevents LH and attenuates uncontrollable stress-induced c-Fos expression in DRN 5-HT neurons, although the duration of wheel running necessary for these effects is unknown.

Employment self-disclosure of postsecondary graduates with learning disabilities: rates and rationales.

One hundred thirty-two graduates with learning disabilities (LD) of a large, public, competitive postsecondary institution were surveyed to determine if they had self-disclosed their LD to their current employer and to provide the reasons for choosing to self-disclose or not to self-disclose. Based on a response rate of 67.4% (n = 89), the results indicated that 86.

Freewheel running prevents learned helplessness/behavioral depression: role of dorsal raphe serotonergic neurons.

Serotonin (5-HT) neurons in the dorsal raphe nucleus (DRN) are implicated in mediating learned helplessness (LH) behaviors, such as poor escape responding and expression of exaggerated conditioned fear, induced by acute exposure to uncontrollable stress. DRN 5-HT neurons are hyperactive during uncontrollable stress, resulting in desensitization of 5-HT type 1A (5-HT1A) inhibitory autoreceptors in the DRN. 5-HT1A autoreceptor downregulation is thought to induce transient sensitization of DRN 5-HT neurons, resulting in excessive 5-HT activity in brain areas that control the expression of learned helplessness behaviors.