Comparison of electrical resistance, bubble withdrawal, and stereotaxic method for cannulation of cerebral ventricles

Antidepressant effect of electroacupuncture on modulating the expression of c-Fos/AP-1 through the JNK signaling pathway

The effectiveness and safety of electroacupuncture (EA) for depression have been identified by abundant clinical trials and experimental findings. The c-Jun-NH(2)-terminal kinase (JNK) signaling pathway is considered to be involved in the antidepressant mechanism of EA. However, the antidepressant effect of EA via modulating the expression of c-Fos/activator protein-1 (AP-1) under the condition of JNK inhibition remains unexplored. In this study, we investigated the antidepressant effect and possible mechanism of EA in regulating the expression of c-Fos/AP-1 under the condition of JNK inhibition by SP600125 in rats exposed to chronic unpredictable mild stress (CUMS). The depression-like behaviors were evaluated by the body weight, sucrose preference test (SPT), and open field test (OFT). The expression levels of c-Jun in the hypothalamus, c-Fos in the pituitary gland, and c-Fos and AP-1 in the serum of CUMS induced rat model of depression were detected by ELISA. The results indicated that treatment with EA and fluoxetine can reverse the CUMS-induced depression-like behaviors in rats and can up-regulate the expression levels of c-Jun in the hypothalamus, c-Fos in the pituitary gland, and c-Fos and AP-1 in the serum. Of note, the data demonstrated that SP600125, the inhibitor of JNK signaling pathway, can exert synergistic effect with EA in regulating CUMS-induced abnormal activation of the JNK signaling pathway. The antidepressant effect of EA might be mediated by modulating the expression of c-Fos/AP-1.

Mechanisms Underlying the Antidepressant Response of Acupuncture via PKA/CREB Signaling Pathway

Protein kinase A (PKA)/cAMP response element-binding (CREB) protein signaling pathway, contributing to impaired neurogenesis parallel to depressive-like behaviors, has been identified as the crucial factor involved in the antidepressant response of acupuncture. However, the molecular mechanisms associated with antidepressant response of acupuncture, neurogenesis, and depressive-like behaviors ameliorating remain unexplored. The objective was to identify the mechanisms underlying the antidepressant response of acupuncture through PKA signaling pathway in depression rats by employing the PKA signaling pathway inhibitor H89 in in vivo experiments. Our results indicated that the expression of hippocampal PKA-α and p-CREB was significantly downregulated by chronic unpredicted mild stress (CUMS) procedures. Importantly, acupuncture reversed the downregulation of PKA-α and p-CREB. The expression of PKA-α was upregulated by fluoxetine, but not p-CREB. No significant difference was found between Acu and FLX groups on the expression of PKA-α and p-CREB. Interestingly, H89 inhibited the effects of acupuncture or fluoxetine on upregulating the expression of p-CREB, but not PKA-α. There was no significant difference in expression of CREB among the groups. Conclusively, our findings further support the hypothesis that acupuncture could ameliorate depressive-like behaviors by regulating PKA/CREB signaling pathway, which might be mainly mediated by regulating the phosphorylation level of CREB.

Nitric oxide regulates body temperature, neuronal activation and interleukin-1 beta gene expression in the hypothalamic paraventricular nucleus in response to immune stress

An immune challenge initiates a complex cascade of events in the body including important responses from the central nervous system. As nitric oxide (NO) has been implicated in the central regulation of neuroendocrine and autonomic responses, this study was performed to determine if NO regulates physiological responses, neuronal activation, and/or interleukin-1 beta (IL-1 beta) gene expression in the paraventricular nucleus of the rat hypothalamus (PVN) in response to intravenous endotoxin, lipopolysaccharide (LPS, 100 microg/kg). Intracerebroventricular injections of NO synthase (NOS) inhibitors (7-nitroindazole sodium salt for neuronal NOS, N(G)-nitro-L-arginine for neuronal NOS and endothelial NOS, and aminoguanidine for inducible NOS) in LPS-treated rats showed that inhibition of NOS eliminated the drop in body temperature and led to increased neuronal activation in the PVN as assessed by immunohistochemistry for Fos-like immunoreactivity. Activation of NO-producing PVN neurons was also increased in these rats suggesting that NO influences neuronal NOS activity in PVN neurons. Finally, increased IL-1 beta gene expression in the PVN of LPS-treated rats receiving N(G)-nitro-L-arginine showed that NO regulates brain IL-1 beta gene expression. The results obtained with the NOS inhibitors support the hypothesis that NO produced from eNOS in the brain participates in temperature regulation, and inhibits PVN neuronal activity and IL-1 beta gene expression during immune stress.

REM sleep deprivation decreases the grooming and shaking behaviour induced by enkephalinase inhibitor or opiate withdrawal

Intraventricular administration of enkephalinase inhibitor, phosphoramidon (1 X 10(-8)-5.6 X 10(-7) moles ICV) induced a behavioural syndrome consisting of excessive grooming with the body scratching as the most prominent symptom and wet-dog-shakes (WDS). The frequency of the phosphoramidon-induced WDS and body scratching were decreased by the pretreatment with the opiate receptor blocking agent, naltrexone (2.9 X 10(-6) moles/kg IP). Both the phosphoramidon-induced WDS in naive rats and naloxone-precipitated withdrawal WDS were decreased in REM sleep deprived rats compared with animals allowed normal sleep (control and stress groups). The results are discussed in light of a possible functional insufficiency of endorphinergic system during REMSD. It has been suggested that this insufficiency might be a background to the increased neuronal excitability during REMSD.

Withdrawal syndrome follows abrupt cessation of intracerebroventricular infusion of epinephrine in spontaneously hypertensive rats

Aortic blood pressure and heart rate were measured directly during chronic (5-day) intracerebroventricular infusion of epinephrine in conscious, unrestrained spontaneously hypertensive rats (SHR), and following abrupt cessation of drug infusion. During the infusion period, no statistically significant differences in mean aortic pressures were observed between SHR that received vehicle and those which received epinephrine at 1.25, 2.5, or 5.0 micrograms (base) per hour for 5 days via osmotic minipumps. A significant reduction in heart rate was noted during some, but not all, days of the epinephrine infusion period; the onset of bradycardia appeared to be dose-related. Immediately following abrupt cessation of epinephrine (but not vehicle) infusion, a complex withdrawal syndrome was observed to include: a significant and sustained elevation of aortic blood pressure, tachycardia, increased water consumption, and several distinct behavioral effects. The reaction appeared maximal at about 2 hours, and lasted less than 24 hours.