BACKGROUND/AIMS: Early adverse life events (EALs) are relevant to irritable bowel syndrome in adulthood. Maternal separation (MS), as one of the EALs, has proved to induce visceral hypersensitivity in adult rats. However, the effect of MS on visceral hypersensitvity from the post-weaning period to adulthood remains unknown. METHODS: One hundred and ten neonatal Sprague-Dawley rats were randomly divided into 2 groups: rats in the MS group were exposed to 3 hours daily MS on postnatal day (PND) 2–14; the normal control (NC) group remained undisturbed. Visceral sensitivity was determined by measuring the visceromotor response to colorectal distention on PND21, 35, and 56. Anxiety-like behaviors were measured by the open field test. RESULTS: Compared with NC rats, MS rats showed significant visceral hypersensitivity from the post-weaning period to adult. The proportion of visceral hypersensitive rats decreased with age from 87.5% to 70.0% in the female MS group and from 90.0% to 66.7% in the male MS group. The relative VMR ratio of MS and NC on PND21 was higher than PND35 and PND56. MS rats showed decreased ability of movement and exploration to the novel environment in the post-weaning period, obesity in the prepubertal period, and more anxiety-like behaviors in adulthood. CONCLUSIONS: MS can significantly affect visceral sensitivity and behaviors of rats in different age stages, especially in the post-weaning period. Visceral hypersensitivity of MS rats is more pronounced in the post-weaning period and slightly restored in adults. Thus, visceral hypersensitivity in the post-weaning period might play a more meaningful pathophysiologic role in the formation of adult irritable bowel syndrome.
Adult ; Animals ; Female ; Humans ; Hypersensitivity* ; Irritable Bowel Syndrome ; Male ; Maternal Deprivation ; Obesity ; Rats ; Rats, Sprague-Dawley

To investigate the intestinal amino acids pathway in depression-like offspring rats induced by maternal separation. Sprague-Dawley (SD) female rats were randomly divided into a control group (=8) and a maternal separation group (=8). After normal delivery, the maternal rats were separated from offsprings for 14 consecutive days and 3 h per day in maternal separation group; while rats in the control group was received no interventions in postpartum. Depression-like behaviors of offspring rats were evaluated using the sucrose preference test, novelty suppressed feeding test, and forced swimming test. Amino acid analyzer was used to detect the changes of amino acid contents in the small intestine, and the expressions of alanine-serine-cysteine transporter 2 (ASCT2), solute carrier superfamily 6 member 19 (BAT1) and L-type amino acid transporter 1(LAT1) were detected by Western blot. The weight of the offspring rats in the maternal separation group was significantly lower than that of the control group at 21 and 28 d (=4.925 and 5.766, all <0.01). Compared with the control group, the percentage of sucrose preference of the offspring rats in the maternal separation group was significantly reduced (=2.709, <0.05), and the feeding latency was significantly prolonged (=-13.431, <0.01). The immobility time in FST of maternal separation group was significantly longer (=-3.616, <0.01).Increased concentration of aspartic acid (=-6.672, <0.01) and down-regulation of glutamine (=3.107, <0.01) and glycine (=9.781, <0.01) were observed in maternal separation group. Western blot analysis revealed that the protein expressions of ASCT2 (=6.734, <0.01) and BAT1 (=9.015, <0.01) in maternal separation group were reduced, while the expression of LAT1 was increased (=-8.942, <0.01). Maternal separation can induce the depression-like behavior in offspring rats; the amino acid contents and the amino acid transporter expression in the small intestine are reduced, which may be related to depression-like behavior induced by maternal separation.
Amino Acids ; Animals ; Depression/etiology* ; Female ; Hippocampus ; Maternal Deprivation ; Rats ; Rats, Sprague-Dawley

Schizophrenia is considered a neurodevelopmental disorder; however, all the available treatment options are used when the disease becomes clinically significant in adolescence or early adulthood. Using a developmental rat model of schizophrenia, we examined whether neonatal treatment with memantine, an NMDA receptor modulator, can improve schizophrenic-like symptoms in adulthood. Early maternal deprivation in rats produces deficits in social interaction behaviors in adulthood. In contrast, memantine administrated in neonatal rats subjected to early maternal deprivation significantly reduces deficits in social interaction behaviors in adulthood. These results raise the possibility that pharmacological treatment with memantine at the early developmental stage helps people with a risk to develop schizophrenic-like symptoms.
Adolescent ; Adult* ; Animals ; Cognition* ; Glutamic Acid ; Humans ; Interpersonal Relations ; Maternal Deprivation* ; Memantine* ; Models, Animal ; N-Methylaspartate ; Neurodevelopmental Disorders ; Neuropharmacology ; Rats* ; Schizophrenia

OBJECTIVETo study the effect of maternal isolation stress on the epilepsy susceptibility in young rats and the possible mechanism.

METHODSSixty Sprague-Dawley young rats were randomly divided into a normal control and two maternal isolation groups that were subjected to maternal isolation for 15 min or 3 hrs daily on postnatal days 2-17. On postnatal day 18, an amygdala kindling test was performed to induce seizures. The expression of GABA(A) receptor α₁ in the hippocampus was determined by immunohistochemisty.

RESULTSThe weights were reduced, the threshold of amygdala kindling and the stimulation number for full kindling decreased significantly, and seizures were more severe in the maternal isolation 3 hrs group compared with the normal control group. The expression of GABA(A) receptor alpha(1) in the hippocampus CA1 area in the maternal isolation 3 hrs group decreased significantly compared with that in the normal groups. There were no significant differences in the aspects above mentioned between the maternal isolation 15 min and normal control groups.

CONCLUSIONSThe stress of early daily maternal isolation for 3 hrs may affect adversely brain development and increase epilepsy susceptibility in young rats. The decreased expression of GABA(A) receptor α₁ in the hippocampus may contribute to the potential mechanism.

Amygdala ; physiology ; Animals ; Disease Susceptibility ; Epilepsy ; etiology ; Female ; Hippocampus ; chemistry ; Kindling, Neurologic ; Maternal Deprivation ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-A ; analysis ; Stress, Psychological ; complications

OBJECTIVE: To detect the expression of miR-16 in the hippocampus of a rat depression model induced by maternal deprivation, and to explore whether miR-16 is involved in the pathological process of maternal deprivation-induced depression. METHODS: Newborn SD rats were randomly divided into a maternal deprivation group (n=17) and a control group (n=17). Rats in the maternal deprivation group experienced maternal deprivation for 6 h per day from 1st to 14th postnatal day, while rats in the control group rats received no treatment. When the rats were 13 weeks old, depression-like behaviors were assessed by forced swimming test and sucrose consumption test, and the expression of hippocampal miR-16 in rats was detected by real-time RT-PCR. RESULTS: Maternal-deprived rats exhibited significantly longer passive floating time and lower sucrose preference rate than rats in the control group (P<0.05). Maternal-deprivation rats expressed higher level of miR-16 in the hippocampus than rats in the control group, and the expression level of miR-16 was significantly associated with the passive floating time (r=0.65, P<0.05) and the sucrose preference rate (r=-0.59, P<0.05). CONCLUSION Maternal deprivation can induce depressive behaviors in rats and increase the expression of miR-16 in the hippocampus in rats. MiR-16 may be involved in the pathological mechanism of the maternal deprivation-induced depression.
Animals ; Animals, Newborn ; Depression ; etiology ; genetics ; Hippocampus ; metabolism ; Male ; Maternal Deprivation ; MicroRNAs ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Stress, Physiological ; physiology

OBJECTIVETo explore the relationship between the expression of brain-derived neurotrophic factor (BDNF) in the spinal dorsal horn and the increase in visceral hypersensitivity in young rats by establishing a young rat model of visceral hypersensitivity by neonatal maternal separation (NMS).

METHODSThirty-two newborn Sprague-Dawley rats were randomly and equally divided into four groups by a 2×2 factorial design: control, NMS, colorectal distension (CRD), and NMS+CRD. The newborn rats in the NMS and NMS+CRD groups were subjected to 3-hour daily maternal separation from days 2 to 14 after birth to establish a model of visceral hypersensitivity, while the rats in the control and CRD groups received no treatment after birth. At 6 weeks after birth, the CRD and CRD+NMS groups received CRD stimulation. The streptavidin-biotin complex immunohistochemical method was used to determine the expression of BDNF in the spinal dorsal horn. The immunohistochemical score (IHS) was calculated based on the percentage of BDNF-positive cells and color intensity. The percentage of BDNF-positive cells in the spinal dorsal horn and IHS were analyzed by factorial analysis of variance.

RESULTSThe expression of BDNF was detected bilaterally in the spinal dorsal horn at different levels in the four groups. The percentage of BDNF-positive cells and IHS were significantly higher in the NMS and NMS+CRD groups than in the control group (P<0.05). The results of factorial analysis of variance indicated that NMS significantly increased the percentage of BDNF-positive cells in the spinal dorsal horn and IHS; a single CRD stimulation had no effects on the IHS of BDNF-positive cells in the spinal dorsal horn; there was no interaction between NMS and a single CRD stimulation.

CONCLUSIONSThe over-expression of BDNF in the spinal dorsal horn may be involved in high visceral hypersensitivity in young rats induce by NMS.

Animals ; Brain-Derived Neurotrophic Factor ; analysis ; Female ; Hyperalgesia ; metabolism ; Immunohistochemistry ; Male ; Maternal Deprivation ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Dorsal Horn ; chemistry ; Visceral Pain ; metabolism

The purpose of this study was to understand the pharmacodynamic effect of Valeriana jatamansi extract in diarrhea predominant irritable bowel syndrome(IBS-D) rat model induced by maternal separation combined with three kinds of stress, and observe the changes of endogenous metabolites in feces after intervention to find potential biomarkers and related metabolic pathways. The animal model of IBS-D was established by maternal separation combined with restraint, ice swimming and tail clamping. The therapeutic effect of each dose group of V. jatamansi extract was evaluated in terms of abdominal withdrawal reflex pressure threshold, fecal water content and immobility time of forced swimming test. In addition, rat feces were collected for detection of metabolic profiles of small molecular metabolites with UPLC-LTQ-Orbitrap MS platform, so as to find the biomarkers of differential metabolism with multivariate statistical analysis methods such as principal component analysis(PCA) and orthogon partial least squares discrimination analysis(OPLS-DA). The results showed that as compared with the normal group, the threshold of abdominal withdrawal reflex pressure was decreased, the fecal water content was increased, and the immobility time of forced swimming test was prolonged in the model group. The results of fecal metabonomics showed that the levels of 39 metabolites were down-regulated and those of 37 metabolites were up-re-gulated. Further analysis showed that these metabolites were related to bile acid metabolism, unsaturated fatty acid metabolism, amino acid metabolism, ceramide metabolism and other metabolic pathways. This study proved that the extract of V. jatamansi had definite pharmacodynamic effect on IBS-D model rats, and the mechanism was discussed from the perspective of fecal metabonomics.
Animals ; Chromatography, High Pressure Liquid ; Chromatography, Liquid ; Diarrhea ; Feces ; Irritable Bowel Syndrome/drug therapy* ; Maternal Deprivation ; Metabolomics ; Rats ; Tandem Mass Spectrometry ; Valerian

OBJECTIVE: To observe the effects of moxibustion on the stem cell factor (SCF)/tyrosine kinase receptor (c-kit) signaling pathway and immune function in rats with diarrhea irritable bowel syndrome (IBS-D), and to explore the mechanism of moxibustion for IBS-D. METHODS: Among 52 young rats born from 6 healthy pregnant SPF rats, 12 rats were randomly selected into the normal group, and the remaining 40 rats were treated with the three-factor combination method of maternal separation, acetic acid enema and chronic restraint stress to establish the IBS-D rat model. Thirty-six rats with successful IBS-D model were randomly divided into a model group, a moxibustion group, and a medication group, 12 rats in each group. The rats in the moxibustion group were treated with suspension moxibustion at "Tianshu" (ST 25) and "Shangjuxu" (ST 37); the rats in the medication group were treated with intragastric administration of rifaximin suspension (150 mg/kg). All the treatments were given once a day for 7 consecutive days. The body mass, loose stool rate (LSR), the minimum volume threshold when abdominal withdrawal reflex (AWR) scored 3 were measured before acetic acid enema (35 days old), after modeling (45 days old), and after intervention (53 days old). After intervention (53 days old), HE staining was used to observe the morphology of colon tissue, and spleen and thymus coefficients were measured; ELISA method was used to detect serum inflammatory factors (tumor necrosis factor a [TNF-a], interleukin [IL]-10, IL-8), T-lymphocyte subsets (CD⁺₄, CD⁺₈, CD⁺₄₅), value of CD⁺₄/CD⁺₈ and immune globulin (IgA, IgG, IgM); real-time PCR method and Western blot method was used to detect the expression of SCF, c-kit mRNA and protein in colon tissue; immunofluorescence staining method were used to detect positive expression of SCF and c-kit. RESULTS: After intervention, compared with the normal group, in the model group, the body mass and the minimum volume threshold when AWR scored 3 were decreased (P<0.01), LSR, spleen and thymus coefficients, serum levels of TNF-α, IL-8, CD⁺₄, CD⁺₄₅, CD⁺₄/CD⁺₈, IgA, IgG, IgM were increased (P<0.01), serum IL-10 level and protein and mRNA expression of SCF and c-kit in colon tissue were decreased (P<0.01), and the positive expression of SCF and c-kit was decreased (P<0.01). Compared with the model group, in the moxibustion group and the medication group, the body mass and the minimum volume threshold when AWR scored 3 were increased (P<0.01, P<0.05), LSR, spleen and thymus coefficients, serum levels of TNF-α, IL-8, CD⁺₄, CD⁺₈, CD⁺₄₅, CD⁺₄/CD⁺₈, IgA, IgG, IgM were decreased (P<0.01, P<0.05), serum IL-10 level and protein and mRNA expression of SCF and c-kit in colon tissue were increased (P<0.01), and the positive expression of SCF and c-kit was increased (P<0.01). Compared with the medication group, in the moxibustion group, the level of serum CD⁺₄ was decreased (P<0.05), the value of CD⁺₄/CD⁺₈ was increased (P<0.01), and there was no significant difference in other indexes (P>0.05). The expression of SCF and c-kit mRNA was positively correlated with the minimum volume threshold when AWR scored 3 and IL-10 (P<0.01), and negatively correlated with remaining indexes (P<0.01, P<0.05). CONCLUSION Moxibustion could reduce visceral hypersensitivity, improve symptoms of abdominal pain and diarrhea in IBS-D rats, and its mechanism may be related to up-regulation of the expression of SCF/c-kit signaling pathway and improvement of IBS-D immune function.
Rats ; Animals ; Irritable Bowel Syndrome/therapy* ; Moxibustion/methods* ; Rats, Sprague-Dawley ; Interleukin-10 ; Interleukin-8 ; Maternal Deprivation ; Tumor Necrosis Factor-alpha ; Diarrhea ; Signal Transduction ; Homeostasis ; Receptor Protein-Tyrosine Kinases ; Immunity ; Immunoglobulin A ; Immunoglobulin M

OBJECTIVETo investigate the effect of maternal deprivation on the activity of hypothalamo-pituitary-adrenal (HPA) axis, acute stress response and the sex hormone receptors expression in hypothalamic paraventricular nucleus (PVN) in female rats.

METHODSMaternal deprivation model was induced in female Sprague-Dawley (SD) rats. Foot shock was given at different stages of estrus cycle during the adulthood. Plasma estradiol, testosterone and adrenocorticotropin (ACTH) levels were determined by radioimmunoassay; and plasma corticosterone level was measured by enzyme linked immunosorbent assay. The expression of androgen receptor (AR) and estrogen receptor (ER-β) in the hypothalamic PVN was detected by immunohistochemistry.

RESULTSDecreased plasma ACTH and corticosterone levels were found in the proestrus of female rats with maternal deprivation (P=0.012 and P=0.019, respectively). A significant down-regulation (P=0.008) of PVN-AR, but not PVN-ER-β expression was found in female rats with maternal deprivation.

CONCLUSIONMaternal deprivation may reduce the HPA axis activity in female SD rats, which is closely correlated with the fluctuation of the circulating sex hormones. The androgen in the hypothalamus seems to play a more important role than the estrogen in this procedure.

Adrenocorticotropic Hormone ; blood ; Animals ; Corticosterone ; blood ; Estradiol ; blood ; Female ; Hypothalamo-Hypophyseal System ; physiopathology ; Maternal Deprivation ; Paraventricular Hypothalamic Nucleus ; metabolism ; Pituitary-Adrenal System ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Receptors, Androgen ; metabolism ; Receptors, Estrogen ; metabolism ; Stress, Physiological ; Testosterone ; blood

The pathophysiology of visceral pain in patients with irritable bowel syndrome remains largely unknown. Our previous study showed that neonatal maternal deprivation (NMD) does not induce visceral hypersensitivity at the age of 6 weeks in rats. The aim of this study was to determine whether NMD followed by adult stress at the age of 6 weeks induces visceral pain in rats and to investigate the roles of adrenergic signaling in visceral pain. Here we showed that NMD rats exhibited visceral hypersensitivity 6 h and 24 h after the termination of adult multiple stressors (AMSs). The plasma level of norepinephrine was significantly increased in NMD rats after AMSs. Whole-cell patch-clamp recording showed that the excitability of dorsal root ganglion (DRG) neurons from NMD rats with AMSs was remarkably increased. The expression of β adrenergic receptors at the protein and mRNA levels was markedly higher in NMD rats with AMSs than in rats with NMD alone. Inhibition of β adrenergic receptors with propranolol or butoxamine enhanced the colorectal distention threshold and application of butoxamine also reversed the enhanced hypersensitivity of DRG neurons. Overall, our data demonstrate that AMS induces visceral hypersensitivity in NMD rats, in part due to enhanced NE-β adrenergic signaling in DRGs.
Adrenergic Agents ; pharmacology ; Animals ; Ganglia, Spinal ; drug effects ; Hyperalgesia ; drug therapy ; physiopathology ; Hypersensitivity ; drug therapy ; Male ; Maternal Deprivation ; Neurons ; drug effects ; Patch-Clamp Techniques ; methods ; Rats, Sprague-Dawley ; Signal Transduction ; drug effects ; Stress, Physiological ; physiology ; Visceral Pain ; chemically induced ; metabolism