Chronic electric stimulation of the midbrain ventral tegmental area increases spleen but not blood natural killer cell cytotoxicity in rats

Subthalamic Deep Brain Stimulation Affects Plasma Corticosterone Concentration and Peripheral Immunity Changes in Rat Model of Parkinson's Disease

Deep brain stimulation of the subthalamic nucleus (DBS-STN) is an effective treatment for advanced motor symptoms of Parkinson's disease (PD). Recently, a connection between the limbic part of the STN and side effects of DBS-STN has been increasingly recognized. Animal studies have shown that DBS-STN influences behavior and provokes neurochemical changes in regions of the limbic system. Some of these regions, which are activated during DBS-STN, are involved in neuroimmunomodulation. The therapeutic effects of DBS-STN in PD treatment are clear, but the influence of DBS-STN on peripheral immunity has not been reported so far. In this study, we examined the effects of unilateral DBS-STN applied in male Wistar rats with 6-hydroxydopamine PD model (DBS-6OHDA) and rats without nigral dopamine depletion (DBS) on corticosterone (CORT) plasma concentration, blood natural killer cell cytotoxicity (NKCC), leukocyte numbers, lymphocyte population and apoptosis numbers, plasma interferon gamma (IFN-γ), interleukin 6 (IL-6), and tumor necrosis factor (TNF-α) concentration. The same peripheral immune parameters we measured also in non-stimulated rats with PD model (6OHDA). We observed peripheral immunity changes related to PD model. The NKCC and percentage of T cytotoxic lymphocytes were enhanced, while the level of lymphocyte apoptosis was down regulated in 6OHDA and DBS-6OHDA groups. After DBS-STN (DBS-6OHDA and DBS groups), the plasma CORT and TNF-α were elevated, the number of NK cells and percentage of apoptosis were increased, while the number of B lymphocytes was decreased. We also found, changes in plasma IFN-γ and IL-6 levels in all the groups. These results suggest potential peripheral immunomodulative effects of DBS-STN in the rat model of PD. However, further studies are necessary to explain these findings and their clinical implication. Graphical Abstract Influence of deep brain stimulation of the subthalamic nucleus on peripheral immunity in rat model of Parkinson's disease.

Studying brain-regulation of immunity with optogenetics and chemogenetics; A new experimental platform

The interactions between the brain and the immune system are bidirectional. Nevertheless, we have far greater understanding of how the immune system affects the brain than how the brain affects immunity. New technological developments such as optogenetics and chemogenetics (using DREADDs; Designer Receptors Exclusively Activated by Designer Drugs) can bridge this gap in our understanding, as they enable an unprecedented mechanistic and systemic analysis of the communication between the brain and the immune system. In this review, we discuss new experimental approaches for revealing neuronal circuits that can participate in regulation of immunity. In addition, we discuss methods, specifically optogenetics and chemogenetics, that enable targeted neuronal manipulation to reveal how different brain regions affect immunity. We describe how these techniques can be used as an experimental platform to address fundamental questions in psychoneuroimmunology and to understand how neuronal circuits associate with different psychological states can affect physiology.

Immuno-enhancement effects of Shenqi Fuzheng Injection on cyclophosphamide-induced immunosuppression in Balb/c mice

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Codonopsis and Radix Astragali, of which Shenqi Fuzheng Injection (SFI) is composed, are commonly used in traditional Chinese medicine to improve immune function against chronic diseases.

AIM OF THE STUDY

The present study was thus designed to systematically elucidate the in vivo immuno-enhancement effects of SFI in immunosuppressed mice induced by cyclophosphamide (Cy) treatment.

MATERIALS AND METHODS

Balb/c mice were injected intraperitoneally (i.p.) once daily with low-dose (2.5 g raw materials/kg), intermediate-dose (5 g raw materials/kg), high-dose (10 g raw materials/kg) of SFI for 10 consecutive days, respectively, accompanied by i.p. injection of Cy (80 mg/kg) on Days 4-6.

RESULTS

Compared with vehicle group, low-, intermediate- and high-dose SFI treatment accelerated recovery dose-dependently of spleen index, peripheral white blood cell and bone marrow cell counts, enhanced T cell and B cell proliferation responses, as well as splenic nature killer cell activity and peritoneal macrophage phagocytosis, and restored the level of interleukin-2 in the serum. Furthermore, SFI treatment promoted recovery of the amount of peripheral white blood cells on Day 6, rather than recombinant human Granulocyte Colony-Stimulating Factor (rhG-CSF) did.

CONCLUSIONS

These results demonstrate, for the first time, that chronic treatment with SFI results in accelerating recovery of immunosuppression in Cy-treated mice, which is competent in taking into consideration for both precautions and remedy. Our findings provide experimental evidences for further researches and clinical application in cancer patients undergoing chemotherapy.

Blood natural killer cell cytotoxicity enhancement correlates with an increased activity in brain motor structures following chronic stimulation of the bed nucleus of the stria terminalis in rats

The present study indicates that a chronic 14 day electrical stimulation of the bed nucleus of the stria terminalis (BST) increased blood but not spleen natural killer cell (NK) cytotoxicity and a large granular lymphocyte (LGL) number. These immune changes positively correlated with the increased activity in brain cortical and subcortical motor structures that influence the BST stimulation-induced behavioral response. No significant changes in blood and spleen leukocyte population numbers and plasma corticosterone concentration after the stimulation were found. The obtained results suggest that this immunoenhancing effect on blood NK cell function and number is dependent on the behavioral outcome of the BST stimulation rather than endocrine response.

Associations among central nervous, endocrine, and immune activities when positive emotions are elicited by looking at a favorite person

Recent studies on psychoneuroimmunology have indicated that positive psychological events are related to immune functions; however, limited information is available regarding associations among the central nervous, endocrine, and immune systems when positive emotions are elicited. In the present study, we demonstrated associations among these systems by simultaneously recording brain, endocrine, and immune activities when positive emotions were evoked in participants as they watched films featuring their favorite persons. Interestingly, the activity of peripheral circulating natural killer cells and the peripheral dopamine level were elevated while participants experienced positive emotions, and these values were positively correlated. The following brain regions were significantly activated in the positive condition relative to the control condition: medial prefrontal cortex, thalamus, hypothalamus, subcallosal gyrus, posterior cingulate cortex, superior temporal gyrus, and cerebellum. Further, covariate analyses indicated that these brain regions were temporally associated with endocrine and immune activities. These results suggest that while an individual experiences positive emotions, the central nervous, endocrine, and immune systems may be interrelated and attraction for favorite persons may be associated with the activation of the innate immune function via the dopaminergic system.

Suppression of natural killer cell cytotoxicity following chronic electrical stimulation of the ventromedial hypothalamic nucleus in rats

In our previous study we found that chronic electrical stimulation of the lateral hypothalamus (LH) enhances and its lesion suppresses natural killer cell cytotoxicity (NKCC) and a large granular lymphocyte (LGL) number in conscious, freely behaving rats. Since the ventromedial nucleus of the hypothalamus (VMH) is regarded as behaviorally and physiologically opposite to LH, in our present study we investigated whether this antagonism also holds for the immune functions. Chronic electrical VMH stimulation effect on 1) immune parameters: both spleen and blood NKCC (chromium release assay and single-cell agarose assay) and the number of large granular lymphocytes (LGL; a morphological method), and 2) endocrine parameters: immunosuppressive-corticosterone (COR) and testosterone (TST) and immunostimulative-growth hormone (GH) and prolactin (PRL) plasma levels (RIA) was assessed. Twenty-one days of electrical stimulation of VMH caused significant decrease in both spleen and blood NKCC at the population level (chromium release assay) but not at the single cell level (agarose assay) with a simultaneous fall in the LGL number. Rats responding to the VMH stimulation with behavioral inactivation (BIN) showed a significantly lower depression of NKCC and LGL number than those responding with an aversive reaction (AVE). Depression of NKCC coexisted with various hormonal changes: increase of PRL, increase (AVE) or fall (BIN) of COR, decrease of GH (BIN), and increase of TST (VMH-stimulated and VMH-sham). There were significant differences in all measured plasma hormones between BIN and AVE groups. The results obtained indicate that VMH decreases cell-mediated immune response, represented by NK cell activity. The immunosuppressive effect is dependent on the behavioral outcome of VMH stimulation (BIN/AVE) rather than tested endocrine variables. Moreover, the present results indicate that the VMH and LH are antagonistically engaged in the regulation of NK cell cytotoxicity.