Influence of brain and behavioral lateralization in brain. Monoaminergic, neuroendocrine, and immune stress responses

Differential responses of stressful elements to predatory exposure in behavior-lateralized mice

BACKGROUND

Predatory stress as a psychological stressor can elicit the activation of the hypothalamic-pituitary-adrenal (HPA) axis, which is involved in the dialogue of the neuroimmunoendocrine network. The brain has been proven to regulate the activity of the HPA axis by way of lateralization. In the present study, we probed the pivotal elements of the HPA circuitry including CRH, GR and a multifunctional cytokine in behavior-lateralized mice to determine their changes when the animals were subjected to predator exposure.

METHODS

Behavior-lateralized mice were classified into left-pawed and right-pawed mice through a paw-preference test. Thereafter, mice in the acute stress group received a single 60-min cat exposure, and mice in the chronic group received daily 60-min cat exposure for 14 consecutive days. The plasma CS and TNF-α were determined by ELISA, the hypothalamic CRH mRNA and hippocampal GR mRNA were detected by real-time PCR, and the hippocampal GR protein was detected by western blot analysis.

RESULTS

The results revealed that the levels of plasma CS were significantly elevated after chronic predatory exposure in both right-pawed and left-pawed mice; the right-pawed mice exhibited a higher plasma CS level than the left-pawed mice. Similarly, the acute or chronic cat exposure could induce the release of plasma TNF-α, and the left-pawed mice tended to show a higher level after the acute stress. Chronic stress significantly upregulated the expression of hypothalamic CRH mRNA in both left-pawed and right-pawed mice. Normally, the left-pawed mice exhibited a higher GR expression in the hippocampus than the right-pawed mice. After the cat exposure, the expression of GR in both left-pawed and right-pawed mice was revealed to be greatly downregulated.

CONCLUSION

Our findings indicate that predatory stress can invoke a differential response of stressful elements in behavior-lateralized mice. Some of these responses shaped by behavioral lateralization might be helpful for facilitating adaption to various stimuli.

Naproxen, a Nonsteroidal Anti-Inflammatory Drug, Can Affect Daily Hypobaric Hypoxia-Induced Alterations of Monoamine Levels in Different Areas of the Brain in Male Rats

Goswami, Ananda Raj, Goutam Dutta, and Tusharkanti Ghosh. Naproxen, a nonsteroidal anti-inflammatory drug can affect daily hypobaric hypoxia-induced alterations of monoamine levels in different areas of the brain in male rats. High Alt Med Biol. 17:133-140, 2016.-The oxidative stress (OS)-induced prostaglandin (PG) release, in hypobaric hypoxic (HHc) condition, may be linked with the changes of brain monoamines. The present study intends to explore the changes of monoamines in hypothalamus (H), cerebral cortex (CC), and cerebellum (CB) along with the motor activity in rats after exposing them to simulated hypobaric condition and the role of PGs on the daily hypobaric hypoxia (DHH)-induced alteration of brain monoamines by administering, an inhibitor of PG synthesis, naproxen. The rats were exposed to a decompression chamber at 18,000 ft for 8 hours per day for 6 days after administration of vehicle or naproxen (18 mg/kg body wt.). The monoamine levels (epinephrine, E; norepinephrine, NE; dopamine, DA; and 5-hydroxytryptamine, 5-HT) in CC, CB, and H were assayed by high-performance liquid chromatography (HPLC) with electrochemical detection, and the locomotor behavior was measured by open field test. The NE and DA levels were decreased in CC, CB, and H of the rat brain in HHc condition. The E and 5-HT levels were decreased in CC, but in H and CB, they remained unaltered in HHc condition. These DHH-induced changes of monoamines in brain areas were prevented after administration of naproxen in HHc condition. The locomotor behavior remained unaltered in HHc condition and after administration of naproxen in HHc condition. The DHH-induced changes of monoamines in the brain in HHc condition are probably linked with PGs that may be induced by OS.

Asymmetric production of nitric oxide in mouse primary cortical mixed glial cell cultures treated with lipopolysaccharide

Activated glial cells produce many toxic molecules, including cytokines and nitric oxide (NO). There is evidence that excess NO production plays a key role in neuronal cell death. Previous research has demonstrated that cortical glial cells from the left and right cortices of the brain secrete cytokines asymmetrically. However, no evidence to date exists about whether glial cell-produced NO is produced asymmetrically as well. The results of this study show that NO production and inducible NO synthase gene expression are both significantly higher in the right hemisphere-derived mixed glial cell compared with cultures derived from the left.

Effect of Bacopa monniera on stress induced changes in plasma corticosterone and brain monoamines in rats

Bacopa monniera (BM) is well known for its neuropharmacological effects. Our previous studies indicated the adaptogenic effect of standardized extract of BM in various stress models. In the present study, effect of BM was evaluated on acute stress (AS) and chronic unpredictable stress (CUS) induced changes in plasma corticosterone and monoamines-noradrenaline (NA), dopamine (DA) and serotonin (5-HT) in cortex and hippocampus regions of brain in rats. Panax root powder (Panax quinquefolium) was taken as standard. Subjecting animals to AS (immobilization for 150 min once only) and CUS (different stressors for 7 days) resulted in significant elevation in plasma corticosterone levels, which was significantly countered by treatment with BM at a dose of 40 and 80 mg/kg p.o. similar to the effects of Panax quinquefolium (PQ) at 100 mg/kg p.o. AS exposure significantly increased the levels of 5-HT and decreased NA content in both the brain regions while DA content was significantly increased in cortex and decreased in hippocampus regions. In CUS regimen, levels of NA, DA and 5-HT were significantly depleted in cortex and hippocampus regions of brain. Treatment with BM (40 and 80 mg/kg) attenuated the stress induced changes in levels of 5-HT and DA in cortex and hippocampus regions but was ineffective in normalizing the NA levels in AS model, whereas PQ treatment significantly reverted back the effects of stress. In CUS model, pretreatment with BM and PQ significantly elevated the levels of NA, DA and 5-HT levels in cortex and levels of NA and 5-HT in hippocampus regions. Hence, our study indicates that the adaptogenic activity of BM might be due to the normalization of stress induced alteration in plasma corticosterone and levels of monoamines like NA, 5-HT and DA in cortex and hippocampus regions of the brain, which are more vulnerable to stressful conditions analogous to the effects of PQ.

Serum interleukin-6 soluble receptor in relation to interleukin-6 in stroke patients

Cerebral ischemia triggers interleukin-6 (IL-6) release into blood. IL-6 is a key mediator of acute phase reaction. Markers of acute phase reaction (C-reactive protein, fibrinogen, fever) have been linked to poor prognosis in stroke patients. Interleukin-6 soluble receptor (sIL-6R) can potentiate IL-6 pro-inflammatory activity. The aim of this study was to investigate the relationship between IL-6 and sIL-6R in stroke patients. Serum cytokine levels were measured in 18 stroke patients and 13 controls using the ELISA method. On the second day of stroke, IL-6 levels were significantly higher in stroke patients than in controls; sIL-6R levels did not differ significantly between groups. Three months after stroke, IL-6 levels did not differ significantly between groups; sIL-6R levels were significantly decreased in stroke patients when compared with that in controls and with levels in acute phase of stroke. Decreased sIL-6R early after stroke might reflect a regulatory mechanism attenuating inflammatory response.

Role of cerebral lateralization in control of immune processes in humans

Cerebral lateralization may be important in neural control of immune function. Animal studies have demonstrated differential effects of left and right brain lesions on immune function, but human studies are inconclusive. Here, we show that resections in the language dominant hemisphere of patients with epilepsy reduce lymphocytes, total T cells, and helper T cells. In contrast, resections in the language nondominant hemisphere increased the same cellular elements. T-cell responses to mitogens and microbial antigens were not differentially affected. Left/right arm histamine skin response ratios were altered in patients with left cerebral epileptic focus, and flare skin responses were reduced by left cerebral resections in contrast with an increase after right cerebral resections. The findings demonstrate a differential role of the left and right cerebral hemispheres on immune functions in humans.

Asymmetrical modulation of interleukin-10 release in patients with intracerebral hemorrhage

The brain modulates the immune system in an asymmetrical way. Intracerebral hemorrhage triggers IL-6 and IL-10 release into blood. We measured (using ELISA method) serum IL-6 and IL-10 in acute phase of intracerebral hemorrhage in 11 patients with right hemisphere's hematoma and 15 patients with left hemisphere's hematoma. These patients did not differ significantly with respect to their age, size, and location of hematoma. IL-6 level was comparable in patients with left hematoma and patients with right hematoma, but patients with left hematoma had significantly higher level of IL-10 than patients with right hematoma. These results suggest that left and right hemisphere could modulate IL-10 release in different way.

Immune consequences of stroke and cerebral palsy in adults

The possibility that brain damage results in a sustained dysregulation of lymphocyte responsiveness to the lymphokine, interleukin-2 (IL-2), was investigated in individuals who had experienced a unilateral stroke in adulthood or who presented with spastic hemiparesis since childhood. Following verification of unilateral brain damage via neuromotor assessment, and determination of their health status, blood samples were obtained to evaluate a panel of immune measures. Soluble interleukin-2 receptor (sIL-2R) and lymphocyte proliferative and cytolytic responses in the subjects with stroke or cerebral palsy were compared to age- and gender-matched controls. In addition, lymphocyte populations were enumerated via flow cytometry, and lymphocyte cyclic AMP (cAMP) levels were determined. Circulating blood levels of sIL-2R were significantly elevated in all individuals that had experienced unilateral brain damage. Cytolytic activity also failed to be stimulated to the normal level by in vitro treatment of lymphocytes with IL-2. Further, lymphocytes from the stroke subjects proliferated significantly less after mitogen and IL-2 stimulation. These functional differences were not accounted for by an abnormal leukocyte profile, although phenotypic analyses revealed subtle differences in the natural killer cell subsets. Overall, the findings indicate that individuals with brain damage may not respond appropriately when immune activation is required. These immune differences appear to be a stable trait given that they were manifested after both perinatal and adult brain insult in otherwise healthy, independently living individuals.

Lateralization and stress responses in mice: interindividual differences in the association of brain, neuroendocrine, and immune responses

Behavioral lateralization, as assessed by paw preference in a food-reaching task in mice, is associated with brain metabolism asymmetries and immune reactivity as well as neuroendocrine and immune stress responses. Therefore, each individual may be characterized by a lateralization score in association with a particular pattern of immune and neuroendocrine reactivities. These interindividual differences may be responsible for the variability among members of a population in the responses to various insults including psychological stressors and infections.