Differences in Behavioral Parameters of Long-Term Pain in Formalin Test at the Period of Sex Maturation in Prenatally Stressed Female and Male Rats

The effect of immobilization of pregnant rats was studied on parameters of the specific biphasic behavioral response (BBR) (patterns of flexion, shaking, licking, duration of the phases and of the interphase interval), of which the first phase characterizes the acute, while the second, he long-term pain in a nociceptive formalin test in the 40-day old female and male off-spring. The following was found: (1) an increase of intensity of patterns of flexion and shaking in the extremity injected with formalin at the second response phase and of the phase duration both in males and in females, (2) an increase of the licking pattern during the second phase and of the phase duration in males. Thus, the prenatal stress produced an increase of the pain sensitivity only at the long-term BBR phase; this increase was revealed in males from the patterns organized at the spinal and supraspinal levels, whereas in females, only at the spinal level. It was concluded that at the period of sex maturation, before the onset of sex maturity, the prenatally stressed males had more expressed damages in the behavioral parameters of the long-term pain in the formalin test, as compared with the prenatally stressed females. The comparative analysis of the response parameters allows suggesting the greater damage in males, then in females, of the inhibition process in the descending inhibitory system modulating nociceptive signals at the spinal cord level.     

Reduced Levels of NR1 and NR2A with Depression-Like Behavior in Different Brain Regions in Prenatally Stressed Juvenile Offspring

Adolescence is a time of continued brain maturation, particularly in limbic and cortical regions, which undoubtedly plays a role in the physiological and emotional changes. Juvenile rats repeatedly exposed to prenatal stress (PS) exhibit behavioral features often observed in neuropsychiatric disorders including depression. However, to date the underlying neurological mechanisms are still unclear. In the current study, juvenile offspring rats whose mothers were exposed to PS were evaluated for depression-related behaviors in open field and sucrose preference test. NMDA receptor subunits NR1 and NR2A in the hippocampus, frontal cortex and striatum were assayed by western blotting. The results indicated that PS resulted in several behavioral anomalies in the OFT and sucrose preference test. Moreover, reduced levels of NMDA receptor subunits NR1 and NR2A in the hippocampus, and NR1 in prefrontal cortex and striatum of prenatally stressed juvenile offspring were found. Treatment with MK-801 to pregnant dams could prevent all those changes in the juvenile offspring. Collectivity, these data support the argument that PS to pregnant dams could induce depression-like behavior, which may be involved with abnormal expression of NR1 and NR2A in specific brain regions, and MK-801 may have antidepressant-like effects on the juvenile offspring.     

动物克隆后代的发育异常

克隆后代发育异常是一种普遍现象,这些异常的发生与供体核的状态,供体的重新程序化以及核外遗传物质等因素存在密切关系,这涉及到印记基因,胚胎早期发育必需基因,染色体的甲基化以及结构的变化等诸多方面的内容,对这些事件的诠释有助于克服克隆后代发育异常的发生。     

Enhanced BDNF Signaling is Associated with an Antidepressant-like Behavioral Response and Changes in Brain Monoamines

1. Neurotrophins and serotonin have both been implicated in the pathophysiology of depression and in the mechanisms of antidepressant treatments. 2. Brain-derived neurotrophic factor (BDNF) influences the growth and plasticity of serotonergic (5-HT) neurons via the activation of trkB receptor. 3. Transgenic mice overexpressing the full-length trkB receptor (TrkB.TK+) and showing increased trkB activity in brain, and their wild type (WT) littermates, were injected with the antidepressant fluoxetine or saline, and analyzed behaviorally in the forced swimming test paradigm and biochemically for the concentrations of brain monoamines and their metabolites. 4. The TrkB.TK+ mice displayed increased latency to immobility in the forced swim test, suggesting resistance to behavioral despair. 5. Fluoxetine increased the latency to immobility in wild-type mice to a similar level as seen in the trkB.TK+ mice after saline treatment, but had no further behavioral effect in the swimming behavior of the trkB.TK+ mice. 6. Only minor differences in the levels of brain monoamines and their metabolites were observed between the transgenic and wild-type mice. 7. These data, together with other recent observations, suggest that trkB activation may play a critical role in the behavioral responses to antidepressant drugs in mice.     

Inside story of Group I Metabotropic Glutamate Receptors (mGluRs)

Metabotropic glutamate receptors (mGluRs) are G-protein coupled receptors (GPCRs) that are activated by the neurotransmitter glutamate in the central nervous system. Among the eight subtypes, mGluR1 and mGluR5 belong to the group I family. These receptors play important roles in the brain and are believed to be involved in multiple forms of experience dependent synaptic plasticity including learning and memory. In addition, group I mGluRs also have been implicated in various neuropsychiatric disorders like Fragile X syndrome, autism etc. The normal signaling depends on the precise location of these receptors in specific region of the neuron and the process of receptor trafficking plays a crucial role in controlling this localization. Intracellular trafficking could also regulate the desensitization, resensitization, down-regulation and intracellular signaling of these receptors. In this review I focus on the current understanding of group I mGluR regulation in the central nervous system and also their role in neuropsychiatric disorders.     

Piperine Reverses Chronic Unpredictable Mild Stress-Induced Behavioral and Biochemical Alterations in Rats

Previous studies in our laboratory have demonstrated that piperine produced antidepressant-like action in various mouse models of behavioral despair, which was related to the serotonergic system. The present study aimed to examine the behavioral and biochemical effects of piperine in rats exposed to chronic unpredictable mild stress (CUMS). The results showed that CUMS caused depression-like behavior in rats, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test. In addition, it was found that serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) contents in the hippocampus and frontal cortex were significantly decreased in CUMS-treated rats. Treating the animals with piperine significantly suppressed behavioral and biochemical changes induced by CUMS. The results suggest that piperine produces an antidepressant-like effect in CUMS-treated rats, which is possibly mediated by increasing 5-HT and BDNF contents in selective brain tissues.     

HIV-1 Transgenic Rats Display Alterations in Immunophenotype and Cellular Responses Associated with Aging

Advances in anti-retroviral therapy over the last two decades have allowed life expectancy in patients infected with the human immunodeficiency virus to approach that of the general population. The process of aging in mammalian species, including rats, results in immune response changes, alterations in immunological phenotypes, and ultimately increased susceptibility to many infectious diseases. In order to investigate the immunological pathologies associated with chronic HIV-1 disease, particularly in aging individuals, the HIV-1 transgenic (HIV-1Tg) rat model was utilized. HIV-1Tg rats were challenged with lipopolysaccharide (LPS) to determine immunological alterations during the aging process. LPS is known to cause an imbalance in cytokine and chemokine release, and provides a method to identify changes in immune responses to bacterial infection in an HIV animal model. An immune profile and accompanying cellular consequences as well as changes in inflammatory cytokine and chemokine release related to age and genotype were assessed in HIV-1Tg rats. The percentage of T cells decreased with age, particularly T cytotoxic cells, whereas T helper cells increased with age. Neutrophils and monocytes increased in HIV-1Tg rats during maturation compared to age-matched F344 control rats. Aging HIV-1Tg rats displayed a significant increase in the pro-inflammatory cytokines, IL-6 and TNF-α, along with an increase in the chemokine, KC/GRO, in comparison to age-matched controls. Our data indicate that immunophenotype and immune responses can change during aging in HIV-positive individuals. This information could be important in determining the most beneficial age-dependent therapeutic treatment for HIV patients.     

Kidney Dysfunction in Adult Offspring Exposed In Utero to Type 1 Diabetes Is Associated with Alterations in Genome-Wide DNA Methylation

Background

Fetal exposure to hyperglycemia impacts negatively kidney development and function.

Objective

Our objective was to determine whether fetal exposure to moderate hyperglycemia is associated with epigenetic alterations in DNA methylation in peripheral blood cells and whether those alterations are related to impaired kidney function in adult offspring.

Design

Twenty nine adult, non-diabetic offspring of mothers with type 1 diabetes (T1D) (case group) were matched with 28 offspring of T1D fathers (control group) for the study of their leukocyte genome-wide DNA methylation profile (27,578 CpG sites, Human Methylation 27 BeadChip, Illumina Infinium). In a subset of 19 cases and 18 controls, we assessed renal vascular development by measuring Glomerular Filtration Rate (GFR) and Effective Renal Plasma Flow (ERPF) at baseline and during vasodilatation produced by amino acid infusion.

Results

Globally, DNA was under-methylated in cases vs. controls. Among the 87 CpG sites differently methylated, 74 sites were less methylated and 13 sites more methylated in cases vs. controls. None of these CpG sites were located on a gene known to be directly involved in kidney development and/or function. However, the gene encoding DNA methyltransferase 1 (DNMT1)—a key enzyme involved in gene expression during early development–was under-methylated in cases. The average methylation of the 74 under-methylated sites differently correlated with GFR in cases and controls.

Conclusion

Alterations in methylation profile imprinted by the hyperglycemic milieu of T1D mothers during fetal development may impact kidney function in adult offspring. The involved pathways seem to be a nonspecific imprinting process rather than specific to kidney development or function.     

The Distribution of Serotonergic Nerves in Microencephalic Rats Treated Prenatally with Methylazoxymethanol

Prenatal exposure of pregnant rats to methylazoxymethanol acetate (MAM) induces microencephaly in the offspring. In the present study of these microencephalic rats (MAM rats) we used quantitative autoradiography to investigate [³H] paroxetine binding sites, which are a selective marker of serotonin (5-HT) transporters (5-HTT). The binding in the accumbens, cortex, hippocampus, and dorsolateral thalamus was significantly increased in MAM rats, compared to the control rats, while there was a significant decrease in the dorsal raphe nucleus of the MAM rats. The levels of 5-HTT mRNA in the dorsal raphe nuclei were analyzed by in situ hybridization, which revealed a significant decrease in 5-HTT mRNA-positive neurons in the MAM rats compared to the control rats. The results imply serotonergic hyperinnervation in the cerebral hemispheres of MAM rats, while a target-dependent secondary degeneration of 5-HT neurons might be induced in the dorsal raphe nuclei of MAM rats.     

Maternal Deprivation Enhances Behavioral Vulnerability to Stress Associated with miR-504 Expression in Nucleus Accumbens of Rats

Objective

In this study, the effect of maternal deprivation (MD) and chronic unpredictable stress (CUS) in inducing depressive behaviors and associated molecular mechanism were investigated in rats.

Methods

Maternal deprivation was established by separating pups from their mothers for 6 hours daily from postnatal day 1 to day 14. Chronic unpredictable stress was established by water deprivation, elevated open platform, food deprivation, restraint stress and electric foot shock. The depressive behaviors were determined by use of sucrose preference test and forced swim test.

Results

Rats in MD/CUS group exhibited lower sucrose preference rate, longer immobility time, and lighter body weights than rats in other groups (MD/control, non-MD/CUS and non-MD/control group). Meanwhile, higher miR-504 expression and lower dopamine receptor D1 (DRD1) and D2 (DRD2) expression were observed in the nucleus accumbens of rats in the MD/CUS group than in the other three groups. MiR-504 expression correlated negatively with DRD1 gene expression and sucrose preference rate in the sucrose preference test, but correlated positively with immobility time in forced swim test. Both DRD2 mRNA and protein expression correlated negatively with immobility time in forced swim test.

Conclusion

These results suggest that MD enhances behavioral vulnerability to stress during adulthood, which is associated with the upregulation of miR-504 and downregulation of DRD2 expression in the nucleus accumbens.     

Neural Stem Cells Grafts Decrease Neural Apoptosis Associated with Caspase-7 Downregulation and BDNF Upregulation in Rats Following Spinal Cord Hemisection

Transplantation of neural stem cells (NSCs) into lesioned spinal cord demonstrated a beneficial effect for neural repair, the underlying mechanism, however, remains to be elusive. Here, we showed that NSCs, possessing the capacity to differentiate toward into neurons and astrocytes, exhibit a neuroprotective effect by anti-apoptosis mechanism in spinal cord hemi-transected rats despite it did not improve behavior. Intravenous NSCs injection substantially upregulated the level of BDNF mRNA but not its receptor TrkB in hemisected spinal cord, while caspase-7, a downstream apoptosis gene of caspase-3, has been largely down-regulated. TUNEL staining showed that the number of apoptosis cells in injured spinal cord decreased significantly, compared with seen in rats with no NSCs administration. The present finding therefore provided crucial evidence to explain neuroprotective effect of NSCs grafts in hemisected spinal cord, which is associated with BDNF upregulation and caspase-7 downregulation.     

Repeated Exposure of Adult Rats to Transient Oxidative Stress Induces Various Long-Lasting Alterations in Cognitive and Behavioral Functions

Exposure of neonates to oxidative stress may increase the risk of psychiatric disorders such as schizophrenia in adulthood. However, the effects of moderate oxidative stress on the adult brain are not completely understood. To address this issue, we systemically administrated 2-cyclohexen-1-one (CHX) to adult rats to transiently reduce glutathione levels. Repeated administration of CHX did not affect the acquisition or motivation of an appetitive instrumental behavior (lever pressing) rewarded by a food outcome under a progressive ratio schedule. In addition, response discrimination and reversal learning were not affected. However, acute CHX administration blunted the sensitivity of the instrumental performance to outcome devaluation, and this effect was prolonged in rats with a history of repeated CHX exposure, representing pro-depression-like phenotypes. On the other hand, repeated CHX administration reduced immobility in forced swimming tests and blunted acute cocaine-induced behaviors, implicating antidepressant-like effects. Multivariate analyses segregated a characteristic group of behavioral variables influenced by repeated CHX administration. Taken together, these findings suggest that repeated administration of CHX to adult rats did not cause a specific mental disorder, but it induced long-term alterations in behavioral and cognitive functions, possibly related to specific neural correlates.     

Motor Disturbances in Offspring of Female Ambidexter Rats with Psychogenic Trauma

The vital stress experienced by mothers both during and before their pregnancy produced motor disturbances in their offspring. By parameters of the EMG activity of the low extremities, more pronounced motor disturbances are revealed in the young 35-day old rat pups whose mothers were exposed to the acute psychogenic trauma during pregnancy. Asymmetry of the motor disturbances is the most prominent in the 45-day old rat pups born from the mothers exposed to the psychogenic trauma one month before pregnancy. In the process of ontogenetic development the revealed deviations are better compensated in the rat pups of the “neonatal stress” group than in the case of their mothers' preconception psychogenic trauma.     

Age-Related Differences in NMDA Receptor Subunits of Prenatally Methamphetamine-Exposed Male Rats

There is accumulating evidence that methamphetamine (MA) is a widely abused drug popular among pregnant women. MA exposure is associated with changes in the function of neurotransmitter systems, namely the dopaminergic, serotonergic and glutamatergic systems. Since N-methyl-d-aspartate receptors (NMDA) are affected by MA-induced glutamate release, we assessed the expression of NMDAR subunits (NR1, NR2A, and NR2B) and postsynaptic density protein 95 (PSD-95), which is connected with NMDAR. We measured the expression of these proteins in adolescent (30 days old) and adult (60 days old) rat males exposed to MA during the entire prenatal period and compared them with the same parameters in age matched saline-exposed rats. There was a significant increase in the NR1 and NR2B subunits in the hippocampus of adult males, but not in adolescent males. We identified a significant change in adult MA-induced rats when compared to adult controls for NR2A and NR2B, while in adolescent MA rats this change was close to the boundary of significance. In summary, our study suggests that prenatal MA exposure is connected with changes in NMDAR subunit expression in adult rats but not in adolescent rats.     

Red Wine Polyphenols Prevent Metabolic and Cardiovascular Alterations Associated with Obesity in Zucker Fatty Rats (Fa/Fa)

Background

Obesity is associated with increased risks for development of cardiovascular diseases. Epidemiological studies report an inverse association between dietary flavonoid consumption and mortality from cardiovascular diseases. We studied the potential beneficial effects of dietary supplementation of red wine polyphenol extract, Provinols™, on obesity-associated alterations with respect to metabolic disturbances and cardiovascular functions in Zucker fatty (ZF) rats.

Methodology/Principal Findings

ZF rats or their lean littermates received normal diet or supplemented with Provinols™ for 8 weeks. Provinols™ improved glucose metabolism by reducing plasma glucose and fructosamine in ZF rats. Moreover, it reduced circulating triglycerides and total cholesterol as well as LDL-cholesterol in ZF rats. Echocardiography measurements demonstrated that Provinols™ improved cardiac performance as evidenced by an increase in left ventricular fractional shortening and cardiac output associated with decreased peripheral arterial resistances in ZF rats. Regarding vascular function, Provinols™ corrected endothelial dysfunction in aortas from ZF rats by improving endothelium-dependent relaxation in response to acetylcholine (Ach). Provinols™ enhanced NO bioavailability resulting from increased nitric oxide (NO) production through enhanced endothelial NO-synthase (eNOS) activity and reduced superoxide anion release via decreased expression of NADPH oxidase membrane sub-unit, Nox-1. In small mesenteric arteries, although Provinols™ did not affect the endothelium-dependent response to Ach; it enhanced the endothelial-derived hyperpolarizing factor component of the response.

Conclusions/Significance

Use of red wine polyphenols may be a potential mechanism for prevention of cardiovascular and metabolic alterations associated with obesity.     

Long-Term Behavioral Programming Induced by Peripuberty Stress in Rats Is Accompanied by GABAergic-Related Alterations in the Amygdala

Stress during childhood and adolescence is a risk factor for psychopathology. Alterations in γ-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the brain, have been found following stress exposure and fear experiences and are often implicated in anxiety and mood disorders. Abnormal amygdala functioning has also been detected following stress exposure and is also implicated in anxiety and social disorders. However, the amygdala is not a unitary structure; it includes several nuclei with different functions and little is known on the potential differences the impact of early life stress may have on this system within different amygdaloid nuclei. We aimed here to evaluate potential regional differences in the expression of GABAergic-related markers across several amygdaloid nuclei in adult rats subjected to a peripuberty stress protocol that leads to enhanced basal amygdala activity and psychopathological behaviors. More specifically, we investigated the protein expression levels of glutamic acid decarboxylase (GAD; the principal synthesizing enzyme of GABA) and of GABA-A receptor subunits α2 and α3. We found reduced GAD and GABA-A α3, but not α2, subunit protein levels throughout all the amygdala nuclei examined (lateral, basolateral, basomedial, medial and central) and increased anxiety-like behaviors and reduced sociability in peripubertally stressed animals. Our results identify an enduring inhibition of the GABAergic system across the amygdala following exposure to early adversity. They also highlight the suitability of the peripuberty stress model to investigate the link between treatments targeting the dysfunctional GABAergic system in specific amygdala nuclei and recovery of specific stress-induced behavioral dysfunctions.     

Possible involvement of group I mGluRs in neuroprotective effect of theanine

We investigated the molecular mechanism underlying the neuroprotective effect of theanine, a green tea component, using primary cultured rat cortical neurons, focusing on group I metabotropic glutamate receptors (mGluRs). Theanine and a group I mGluR agonist, DHPG, inhibited the delayed death of neurons caused by brief exposure to glutamate, and this effect of theanine was abolished by group I mGluR antagonists. Although the administration of glutamate alone decreased the neuronal expression of phospholipase C (PLC)-beta1 and -gamma1, which are linked to group I mGluRs, their expression was equal to the control levels on cotreatment with theanine. Treatment with theanine or DHPG alone for 5-7 days resulted in increased expression of PLC-beta1 and -gamma1, and the action of theanine was completely abolished by group I mGluR antagonists. These findings indicate that group I mGluRs might be involved in neuroprotective effect of theanine by increasing the expression levels of PLC-beta1 and -gamma1.     

Salivary Alterations in Rats with Experimental Chronic Kidney Disease

Objective

This study aimed to analyze changes in saliva composition and salivary secretion process of rats with chronic kidney disease induced by 5/6 nephrectomy to set the foundation for salivary studies related to CKD.

Methods

CKD was induced in Wistar rats via 5/6 nephrectomy. Blood and saliva samples were collected from Control, Sham and CKD groups at 8 and 12 weeks after the surgery. Salivation was stimulated via intraperitoneal injections of pilocarpine (1.0 mg/Kg body weight) or isoproterenol (5.0 mg/Kg body weight). Saliva was collected and immediately stored at -80°C until analysis. The salivary flow rate, total protein, amylase and peroxidase activities, and urea concentrations were measured. The blood urea nitrogen (BUN) and serum creatinine concentrations were also evaluated.

Results

Increases in BUN and serum creatinine concentrations were observed in the CKD groups. Amylase activity was significantly reduced in response to both stimuli in the CKD groups at 8 weeks and increased in the CKD groups at 12 weeks in response to isoproterenol stimulus. The peroxidase activities of the CKD groups were significantly reduced in response to isoproterenol stimulation and were increased at 12 weeks in response to pilocarpine stimulation. Salivary urea was significantly increased in the CKD groups at 8 weeks in response to the isoproterenol stimuli and at 12 weeks in response to both salivary agonists.

Conclusions

The pattern of alterations observed in this experimental model is similar to those observed in patients and clearly demonstrates the viability of 5/6 nephrectomy as an experimental model in future studies to understand the alterations in salivary compositions and in salivary glands that are elicited by CKD.