PPARα contributes to colonic protection in mice with DSS-induced colitis

Inflammatory bowel disease (IBD) is characterized by repeated chronic inflammation of the gastrointestinal tract. We have used the complementary model of colonic inflammation to examine the roles of peroxisome proliferator-activated receptor α (PPARα) in colonic inflammation and thus its possible role in IBD. We characterized an innate immune-mediated model of colitis induced by dextran sulfate sodium (DSS). Mice with DSS-induced colitis were injected with Wy-14643 (2 mg/kg) as a PPARα agonist every day from day 0 to day 5. We show that mice given Wy-14643 were less susceptible to experimental acute colitis induced by DSS, and this decreased susceptibility was correlated with decreased production of IFNγ, IL-1β, IL-6, and TNF-α. Our findings suggest that PPARα has a role in controlling colonic inflammation and mucosal tissue homeostasis.     

Is behavioral sensitization to ethanol associated with contextual conditioning in mice?

Behavioral sensitization to drugs of abuse seems to involve learning processes. In mice, ethanol-induced locomotor sensitization is potentiated by repeated pairing of ethanol (EtOH) injections and the testing chamber. The present study aimed to test: (1). the association between the performance in a contextual conditioning task and the development of behavioral sensitization to EtOH in mice; (2). whether EtOH sensitization would be expressed in a different testing environment. Male albino Swiss mice (n=72) were initially submitted to a contextual fear conditioning task. After 2 weeks without manipulation, the animals received daily i.p. injections of 2.2 g/kg EtOH (n=52) or saline (n=20), for 21 days. They were tested weekly for locomotor activity in activity cages. After 1 week of withdrawal, all mice received 2.2 g/kg EtOH and had their locomotor activity recorded in an open-field. According to the locomotor behavior displayed along the 21-day treatment, EtOH-treated mice were classified as sensitized (n=15) or non-sensitized (n=15). When these subgroups and saline-treated mice were compared for the freezing response in the conditioning test, sensitized mice displayed a greater freezing time than non-sensitized mice. When challenged with EtOH in the open-field, none of the EtOH-treated subgroups expressed behavioral sensitization. These results suggest that the development of EtOH sensitization seems to be positively associated with contextual learning, and further confirms that the expression of sensitization is highly dependent on contextual cues.     

Tumour-associated macrophages targeted transfection with NF-κB decoy/mannose-modified bubble lipoplexes inhibits tumour growth in tumour-bearing mice

Abstract

Tumour-associated macrophages (TAM) exhibit an M2 phenotype that promotes tumour progression, and conversion of M2 TAM toward a tumouricidal M1 phenotype is a promising anti-cancer therapy. As NF-κB is a key regulator of macrophage polarization, we developed an in vivo TAM-targeting delivery system that combines mannose-modified bubble liposomes/NF-κB decoy complexes (Man-PEG bubble lipoplexes) and ultrasound (US) exposure. We investigated the effects of NF-κB decoy transfection on TAM phenotype in solid tumour-bearing mice. Post-transfection tumour growth and survival rates were also recorded. Th2 cytokine (IL-10) level in TAM was significantly lower by NF-κB decoy transfection using Man-PEG bubble lipoplexes and US exposure, while Th1 cytokine levels (IL-1β, TNF-α and IL-6) were significantly higher when compared with controls. In addition, mRNA levels of vascular endothelial growth factor, matrix metalloproteinase-9 and arginase were significantly lower in TAM post-NF-κB decoy transfection. Importantly, TAM-targeted NF-κB decoy transfection inhibited tumour growth and prolonged survival rates in mice. Therefore, TAM-targeted NF-κB decoy transfection using Man-PEG bubble lipoplexes and US exposure may be an effective approach for anti-cancer therapy based on TAM phenotypic conversion from M2 toward M1.     

Expression of β-catenin in lung tissues of mice with pulmonary fibrosis

目的 观察β-连环蛋白在肺纤维化模型小鼠肺组织中的表达.方法 昆明小鼠40只随机均分成实验组和对照组,气管内分别一次性注入博来霉素5 mg/kg(0.04 ml)和生理盐水0.04 ml.给药后第3、7、14、28天,每组处死小鼠5只,取肺组织做病理切片和HE染色;用碱水解法检测肺组织羟脯氨酸含量,免疫组化法及Western blot检测肺组织中β-连环蛋白表达.结果 实验组肺泡炎和肺纤维化程度均明显高于对照组(P＜0.05),羟脯氨酸的含量在第7-28天明显高于对照组(P＜0.01).实验组在各时间点肺组织中的β-连环蛋白表达高于对照组(P＜0.05);其表达高峰在第14天.结论 β-连环蛋白在模型小鼠肺纤维化发生过程中存在高表达.     

Immunohematopoietic modulation by oral β-1,3-glucan in mice infected with Listeria monocytogenes

In this study we demonstrated that the oral administration of β-1,3-glucan (Imunoglucan?) protects mice from a lethal dose of Listeria monocytogenes (LM) when administered prophylactically for 10 days at the doses of 150 and 300 mg/kg, with survival rates up to 40%. These doses also prevented the myelosuppression and the splenomegaly caused by a sublethal infection with LM, due to increased numbers of granulocyte-macrophage progenitors (CFU-GM) in the bone marrow. Investigation of the production of colony-stimulating factors revealed an increased colony-stimulating activity (CSA) in the serum of infected mice pre-treated with Imunoglucan?. The treatment also restored the reduced ability of stromal cells to display myeloid progenitors in long-term bone marrow cultures (LTBMC) and up-regulated IL-6 and IL-1α production by these cells in the infected mice, which was consistent with higher number of non-adherent cells. Additional studies to investigate the levels of interferon-gamma (INF-γ) in the supernatant of splenocyte cultures demonstrated a further increase in the level of this cytokine in infected-treated mice, compared to infected controls. In all cases, no differences were observed between the responses of the two optimal biologically effective doses. In contrast, no significant changes were produced by the treatment with the 50mg/kg dose. In addition, no changes were observed in normal mice treated with the three doses used. All together our results suggest that orally given Imunoglucan? indirectly modulates immune activity and probably disengages Listeria induced suppression of these responses by inducing a higher reserve of myeloid progenitors in the bone marrow in consequence of biologically active cytokine release (CSFs, IL-1α, IL-6, and INF-γ).     

Survival and differentiation of transplanted neural stem cells in mice brain with MPTP-induced Parkinson disease

AIM: To determine survival and differentiation of cultured neural stem cells (NSCs) into viable and functional neurons upon transplantation into mice brain of MPTP-induced Parkinson disease (PD). METHODS: Mouse model of PD was established with two subcutaneous (sc) injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 40 mg/kg) twice, 16h apart. NSCs isolated from rat embryo midbrain were cultured in clonal density. After labeled with 5-bromo-2'-deoxyuridine (BrdU), the NSCs were transplanted into the uni-or bi-lateral striatum of PD mouse. Tyrosine hydroxylase (TH) immunofluorescence was used to evaluate the toxicity of MPTP on the neural cells in the substantia nigra. Immunohistology and laser confocal microscope were used to detect the survival and differentiation of transplanted NSCs. RESULTS: The cultured NSCs generated neurospheres and differentiated into neuron and astrocyte. It indicated that the cultured NSCs were multipotent and self-renewal in vitro. TH-positive neural cells were     

β3-adrenoceptor-mediated increased circulating transaminase levels in mice treated with its agonist BRL 37344

Treatment with the selective β(3)-adrenoceptor agonist BRL 37344 increased circulating levels of alanine transaminase (ALT) and aspartate transaminase (AST) in mice without causing hepatocellular injury. To clarify whether this was a β(3)-adrenoceptor-mediated effect, the inhibitory effect of the selective β(3)-adrenoceptor antagonist SR 59230A on the increase in circulating transaminase levels induced by BRL 37344 was examined. A single intraperitoneal dose of BRL 37344 alone initially increased insulin and non-esterified fatty acid (NEFA) dose-proportionally at 0.5 hr post-dose, findings considered attributable to β(3)-adrenoceptor-stimulating effects. Levels of the gluconeogenic precursors pyruvate (PA) and lactate (LA) were increased corresponding to the change in insulin. Thereafter, glucose (GLU) level was decreased at 4 and 8 hr post-dose, suggesting disruption of glucose homeostasis. In association with these changes in glucose metabolism, transaminase levels were increased maximally at 4 hr post-dose. The transaminase changes were not accompanied by increases in circulating levels of other hepatocellular enzymes, including guanine deaminase (GUA), glutamate dehydrogenase (GLDH), and lactate dehydrogenase (LDH), or any morphological hepatocellular injury. Intraperitoneal pre-treatment with SR 59230A partly inhibited the effects of BRL 37344 alone, indicating that the increase in levels of circulating ALT by BRL 37344 was attributable to a β(3)-adrenoceptor-stimulating effect. In conclusion, the β(3)-adrenoceptor agonist BRL 37344 was shown to increase circulating transaminase levels in mice accompanied with dynamic changes in glucose metabolism. These findings suggest the possibility that circulating transaminase levels are increased as pharmacological effects of drugs disrupting glucose metabolism, and that hepatotoxic markers should be selected considering these effects to distinguish between acceptable pharmacology and toxicity.     

Effects of berberine on colon dermal cell apoptosis in mice with ulcerative colitis based on JAK/STAT signaling pathway北大核心CSCD

Aim To analyze the effects of berberine on the apoptosis of colon epithelial cells and polymorpho-nuclear neutrophils ( PMNs) in mice with ulcerative colitis ( UC ) by regulating JAK/STAT signaling pathway. Methods The UC mouse models were established by dextran sulfate sodium ( DSS) method and were randomly divided into control group, UC group, low-dose, middle-dose and high-dose berberine groups and positive drug group ( mesalazine enteric-coated tablet group) . In addition, the mice were randomly di¬vided into UC group, high-dose berberine group, AG490 group, and high-dose berberine + AG490 group. Levels of serum tumor necrosis factor a (TNF-α) and interleukin 6 (IL-6) and colon epithelial cell apoptosis and PMN apoptosis were compared among the groups. Western blot was used to detect the expres¬sions of colon tissue apoptosis-related and JAK/STAT signaling pathway-related proteins. Results The lev¬els of serum TNF-α and IL-6, apoptosis rate of colon epithelial cell and protein expressions of Fas, FasL, Bax, caspase-3, p-JAK2/JAK2 and p-STAT3/STAT3 in each dose berberine group and positive drug group were significantly lower than those in UC group (P < 0.05), and the above indicators in berberine groups were reduced gradually (P <0.05) . The PMN apoptosis rate and Bcl-2 protein expression were significantly higher in each dose berberine group and positive drug group than those in UC group (P <0. 05) , and the two indicators increased gradually in berberine groups ( P < 0.05). AG490 could reverse the above effects of berberine ( P < 0. 05 ). Conclusions Berberine can inhibit the apoptosis of colon epithelial cell and promote the apoptosis of PMN in UC mice by regulating the JAK/STAT signaling pathway, and then play a role in the treatment of UC. © 2023 Publication Centre of Anhui Medical University. All rights reserved.     

Antidiabetic effect of a novel non-thiazolidinedione PPAR γ/α agonist on ob/ob mice

AIM: To study whether T33, a new synthesized non-thiazolidinedione (TZD) peroxisome proliferator-activated receptor (PPAR) gamma/alpha dual agonist has an antidiabetic effect on ob/ob mice. METHODS: Ob/ob mice were treated with 4 mg/kg or 8 mg/kg T33 by gavage for 20 d. Blood glucose levels were measured regularly. An oral glucose tolerance test (OGTT) and an insulin tolerance test (ITT) were preformed on d 8 and d 12, respectively. The levels of insulin, triglyceride and free fatty acid (FFA) in the serum were measured at the end of administration. The intramuscular and liver triglyceride content was also determined. RESULTS: T33 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia of the ob/ob mice. The OGTT and ITT showed that the insulin resistance state of the ob/ob mice was obviously ameliorated after T33 treatment. After 20 d treatment with 8 mg/kg T33, the triglyceride content in the gastrocnemius muscle decreased significantly. T33 did not have any effect on triglyceride content in the liver, whereas rosiglitazone significantly increased the hepatocyte lipid deposition. CONCLUSION: The PPARgamma/alpha dual agonist T33 has antidiabetic and insulin-sensitizing effects in ob/ob mice. It has the potential to be a new therapeutic candidate for the treatment of type 2 diabetes.     

Chronic treatment with a MEK inhibitor reverses enhanced excitatory field potentials in Syngap1+/− mice

Background

Synaptic Ras-GTPase-activating protein 1 (SYNGAP1) is an abundant brain-specific protein localized at the postsynaptic density of mammalian excitatory synapses. SYNGAP1 functions as a crucial regulator of downstream intracellular signaling triggered by N-methyl-d-aspartate receptor activation. One of the most important signaling pathways regulated by SYNGAP1 is the Ras-Raf-MEK-ERK pathway. SYNGAP1 deficiency is associated with hyperphosphorylation of MEK and ERK kinases and with altered synaptic function in Syngap1^+/? mice. Loss-of-function mutations in the SYNGAP1 gene have been documented in many human cognitive and neurological disorders. However, there are currently no approaches that reverse the phenotypes of SYNGAP1 deficiency.

Does angiotensin interact with dopaminergic mechanisms in the brain to modulate prepulse inhibition in mice?

Changes in the levels of angiotensin-converting enzyme (ACE) have been found in brains of schizophrenia patients, suggesting a possible involvement of angiotensin in the illness. Prepulse inhibition (PPI) is a measure of sensorimotor gating and is disrupted in patients with schizophrenia. In a previous study, a reduction of ACE activity, either in ACE knockout mice or after ACE inhibitor treatment, markedly inhibited the disruption of PPI caused by the dopamine receptor agonist, apomorphine. ACE is not specific for the angiotensin system and, therefore, in the present study we assessed pharmacological regulation of PPI in two other, more specific genetic mouse models of altered angiotensin activity. We used renin-enhancer knockout (REKO) mice, which display reduced renin activity, and neuron-specific enolase (NSE)-AT1A mice, which selectively over-express angiotensin AT1A receptors in the brain. Treatment of these mice with apomorphine, the dopamine releaser, amphetamine or the NMDA receptor antagonist, MK-801, significantly disrupted PPI. There was, however, no difference in these effects between the genotypes. These data suggest that genetically induced changes in the activity of the angiotensin system do not alter regulation of PPI in mice. Our previous results on the effects of reduced ACE activity could be explained by mechanisms other than angiotensin, such as effects on enkephalin or bradykinin metabolism.     

Cardiovascular effects of chronic treatment with a β2-adrenoceptor agonist relieving neuropathic pain in mice

Neuropathic pain is often a chronic condition, disabling and difficult to treat. Using a murine model of neuropathic pain induced by placing a polyethylene cuff around the main branch of the sciatic nerve, we?have shown that chronic treatment with β-AR agonists is effective against neuropathic allodynia. β-mimetics are widely used against asthma and chronic obstructive pulmonary disease and may offer an interesting option for neuropathic pain management. The most prominent adverse effects of chronic treatment with β-mimetics are cardiovascular. In this study, we compared the action of low doses of the selective β(2)-AR agonist terbutaline and of a high dose of the mixed β(1)/β(2)-AR agonist isoproterenol on cardiovascular parameters in a neuropathic pain context. Isoproterenol was used as a positive control for some heart-related changes. Cardiac functions were studied by echocardiography, hemodynamic measurements, histological analysis of fibrosis and cardiac hypertrophy, and by quantitative real time PCR analysis of atrial natriuretic peptide (Nppa), periostin (Postn), connective tissue growth factor (Ctgf) and β-myosin heavy chain (Myh7). Our data show that a chronic treatment with the β(2)-AR agonist terbutaline at low antiallodynic dose does not affect cardiovascular parameters, whereas the mixed β(1)/β(2)-AR agonist isoproterenol induces cardiac hypertrophy. These data suggest that low doses of β(2)-AR agonists may provide a suitable treatment with rare side effects in neuropathic pain management. This study conducted in an animal model requires clinical confirmation in humans.     

Liposomes modified with P-aminophenyl-α-d-mannopyranoside: A carrier for targeting cerebral functional regions in mice

Targeting of intracerebral functional regions has been limited by the inability to transport drugs across the blood–brain barrier (BBB) and by poor accumulation in these regions. To overcome these hurdles, liposomes modified with P-aminophenyl-α-d-mannopyranoside (MAN) were used as a fluorescent dye carrier through the BBB and used the specific distribution of liposomes (LIP) modified with MAN (MAN–LIP) to target various functional regions of the brain. An in vitro BBB model was established to evaluate the transendothelial ability of MAN–LIP, and liposomes uptake by C6 glioma cells was analyzed by flow cytometry and live cell imaging. Liposome targeting was evaluated using in vivo and ex vivo imaging. After MAN–LIP administration, the transendothelial ability and the delivery of fluorescent dye to the brain significantly increased. MAN–LIP concentrated in the cortex at 4 h, shifting distribution to the cerebellum and brainstem at 12 h. The fluorescence intensity in the hippocampus and pontine nuclei remained high and stable over a period of 12 h. The results demonstrate that MAN–LIP is able to enhance cellular uptake in vitro and also promotes penetration through the BBB and accumulation in the brain with a distinct spatio-temporal pattern.     

Induction of systemic lupus erythematosus syndrome in BALB／c mice by immunization with active chromatin

AIM: To establish an animal model for systemic lupus erythematosus (SLE)-like syndrome in mice. METHODS:BALB/c mice were immunized with active chromatin isolated from ConA-actived syngeneic spleno-lymphocytes.Plasma samples of mice were tested by enzyme-linked immunosorbent assays (ELISA) for the presence of IgG anti-dsDNA, -ssDNA, and anti-histone antibodies. Tumor necrosis factor-α(TNF-α) in serum was measured by ELISA. Spleno-lymphocyte proliferation assays and the levels of interferon-γ(IFN-γ) in supematants were tested respectively. Proteinuria was measured. Kidneys were examined by direct immunohistochemical method and fight microscopy. RESULTS： Anti-ds DNA, ssDNA, and histone antibodies were induced in active chromatin-immunized mice, the proliferation response of splenocytes to ConA and LPS were reduced, levels of interferon-γ in supernatants and TNF-at in serum were lowered. Lupus nephritis was assessed by the presence of Ig deposits,glomerular pathology and proteinuria. CONCLUSION: The active chromatin-induced SLE-like mouse model was similar to idiopathic SLE in human.     

Antigenotoxic effect of acute,subacute and chronic treatments with Amazonian camu–camu (Myrciaria dubia) juice on mice blood cells

Myrciaria dubia, a plant native to the Amazon region, stands out as a fruit rich in vitamin C and other metabolites with nutritional potential. We evaluated the antioxidant, genotoxic and antigenotoxic potential of M. dubia juice on blood cells of mice after acute, subacute and chronic treatments. Flavonoids and vitamin C present in the fruit of M. dubia were quantified. In vitro antioxidant activity was evaluated by DPPH assay. Blood samples were collected for analysis after treatment, and the alkaline comet assay was used to analyze the genotoxic and antigenotoxic activity (ex vivo analysis using H₂O₂). The amount of vitamin C per 100 mL of M. dubia was 52.5 mg. DPPH assay showed an antioxidant potential of the fruit. No M. dubia concentration tested exerted any genotoxic effect on mice blood cells. In the ex vivo test, the juice demonstrated antigenotoxic effect, and acute treatment produced the most significant results. After the treatments, there was no evidence of toxicity or death. In conclusion, our data show that M. dubia juice has antigenotoxic and antioxidant activities, though with no genotoxicity for blood cells. Nevertheless, more in-depth studies should be conducted to assess the safety of this fruit for human consumption.     

Inflammasome activity is essential for one kidney/deoxycorticosterone acetate/salt‐induced hypertension in mice

Background and Purpose

Inflammasomes are multimeric complexes that facilitate caspase‐1‐mediated processing of the pro‐inflammatory cytokines IL‐1β and IL‐18. Clinical hypertension is associated with renal inflammation and elevated circulating levels of IL‐1β and IL‐18. Therefore, we investigated whether hypertension in mice is associated with increased expression and/or activation of the inflammasome in the kidney, and if inhibition of inflammasome activity reduces BP, markers of renal inflammation and fibrosis.

Experimental Approach

Wild‐type and inflammasome‐deficient ASC ^−/− mice were uninephrectomized and received deoxycorticosterone acetate and saline to drink (1K/DOCA/salt). Control mice were uninephrectomized but received a placebo pellet and water. BP was measured by tail cuff; renal expression of inflammasome subunits and inflammatory markers was measured by real‐time PCR and immunoblotting; macrophage and collagen accumulation was assessed by immunohistochemistry.

Key Results

1K/DOCA/salt‐induced hypertension in mice was associated with increased renal mRNA expression of inflammasome subunits NLRP3, ASC and pro‐caspase‐1, and the cytokine, pro‐IL‐1β, as well as protein levels of active caspase‐1 and mature IL‐1β. Following treatment with 1K/DOCA/salt, ASC ^−/− mice displayed blunted pressor responses and were also protected from increases in renal expression of IL‐6, IL‐17A, CCL2, ICAM‐1 and VCAM‐1, and accumulation of macrophages and collagen. Finally, treatment with a novel inflammasome inhibitor, MCC950, reversed hypertension in 1K/DOCA/salt‐treated mice.

Conclusions and Implications

Renal inflammation, fibrosis and elevated BP induced by 1K/DOCA/salt treatment are dependent on inflammasome activity, highlighting the inflammasome/IL‐1β pathway as a potential therapeutic target in hypertension.

Linked Articles

This article is part of a themed section on Inflammation: maladies, models, mechanisms and molecules. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2016.173.issue-4

Abbreviations

AIM2

absent in melanoma 2

ASC

apoptosis‐associated speck‐like protein containing a carboxy‐terminal CARD

CARD

caspase activation and recruitment domain

CCL

C‐C motif chemokine ligand

DAMP

danger‐associated molecular pattern

DOCA

deoxycorticosterone acetate

HRP

horseradish peroxidase

ICAM‐1

intercellular adhesion molecule‐1

NLRC4 (IPAF)

NOD‐like receptor family CARD domain‐containing protein 4

NLRP

NOD‐like receptor family pyrin domain‐containing protein

PAMP

pathogen‐associated molecular pattern

VCAM‐1

vascular cell adhesion molecule‐1

Tables of Links

Cannabinoid CB₂ receptor-mediated regulation of impulsive-like behaviour in DBA/2 mice

BACKGROUND AND PURPOSE

This study evaluated gene expression differences between two mouse strains, characterized by opposite impulsivity-like traits and the involvement of the cannabinoid CB₂ receptor in the modulation of impulsivity.

EXPERIMENTAL APPROACH

Behavioural tests were conducted to compare motor activity, exploration and novelty seeking, attention and cognitive and motor impulsivity (delayed reinforcement task: session duration 30 min; timeout 30 s) between A/J and DBA/2 mice. Expression of genes for dopamine D₂ receptors, CB₁ and CB₂ receptors were measured in the cingulate cortex (CgCtx), caudate-putamen (CPu), accumbens (Acc), amygdala (Amy) and hippocampus (Hipp). Involvement of CB₂ receptors in impulsivity was evaluated in DBA/2 mice with a CB₂ receptor agonist (JWH133) and an antagonist (AM630).

KEY RESULTS

DBA/2 mice presented higher motor and exploratory activity, pre-pulse inhibition impairment and higher cognitive and motor impulsivity level than A/J mice. In addition, DBA/2 mice showed lower (CgCtx, Acc, CPu) D₂ receptor, lower (Amy) and higher (CgCtx, Acc, CPu, Hipp) CB₁ receptor and higher (CgCtx, Acc, Amy) and similar (CPu, Hipp) CB₂ receptor gene expressions. Treatment with JWH133 (0.5, 1, 3 mg·kg⁻¹, i.p.) reduced cognitive and motor impulsivity level, accompanied by CB₂ receptor down-regulation (CgCtx, Acc, Amy) but did not modify other behaviours. In contrast, AM630 (1, 2, 3 mg·kg⁻¹, i.p.) improved pre-pulse inhibition and reduced novelty seeking behaviour in DBA/2 mice.

CONCLUSIONS AND IMPLICATIONS

CB₂ receptors might play an important role in regulating impulsive behaviours and should be considered a promising therapeutic target in the treatment of impulsivity-related disorders.     

Behavioural and biochemical evidence for signs of abstinence in mice chronically treated with Δ-9-tetrahydrocannabinol

1. Tolerance and dependence induced by chronic Δ-9-tetrahydrocannabinol (THC) administration were investigated in mice. The effects on body weight, analgesia and hypothermia were measured during 6 days of treatment (10 or 20 mg kg⁻¹ THC twice daily). A rapid tolerance to the acute effects was observed from the second THC administration.
2. The selective CB-1 receptor antagonist SR 141716A (10 mg kg⁻¹) was administered at the end of the treatment, and somatic and vegetative manifestations of abstinence were evaluated. SR 141716A administration precipitated several somatic signs that included wet dog shakes, frontpaw tremor, ataxia, hunched posture, tremor, ptosis, piloerection, decreased locomotor activity and mastication, which can be interpreted as being part of a withdrawal syndrome.
3. Brains were removed immediately after the behavioural measures and assayed for adenylyl cyclase activity. An increase in basal, forskolin and calcium/calmodulin stimulated adenylyl cyclase activities was specifically observed in the cerebellum of these mice.
4. The motivational effects of THC administration and withdrawal were evaluated by using the place conditioning paradigm. No conditioned change in preference to withdrawal associated environment was observed. In contrast, a conditioned place aversion was produced by the repeated pairing of THC (20 mg kg⁻¹), without observing place preference at any of the doses used.
5. This study constitutes a clear behavioural and biochemical model of physical THC withdrawal with no motivational aversive consequences. This model permits an easy quantification of THC abstinence in mice and can be useful for the elucidation of the molecular mechanisms involved in cannabinoid dependence.

     

Combining a dipeptidyl peptidase-4 inhibitor, alogliptin, with pioglitazone improves glycaemic control, lipid profiles and ��-cell function in db/db mice

Background and purpose:

Alogliptin, a highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, enhances incretin action and pioglitazone enhances hepatic and peripheral insulin actions. Here, we have evaluated the effects of combining these agents in diabetic mice.

Experimental approach:

Effects of short-term treatment with alogliptin alone (0.01%–0.1% in diet), and chronic combination treatment with alogliptin (0.03% in diet) and pioglitazone (0.0075% in diet) were evaluated in db/db mice exhibiting early stages of diabetes.

Key results:

Alogliptin inhibited plasma DPP-4 activity up to 84% and increased plasma active glucagon-like peptide-1 by 4.4- to 4.9-fold. Unexpectedly, alogliptin alone lacked clear efficacy for improving glucose levels. However, alogliptin in combination with pioglitazone clearly enhanced the effects of pioglitazone alone. After 3–4 weeks of treatment, combination treatment increased plasma insulin by 3.8-fold, decreased plasma glucagon by 41%, both of which were greater than each drug alone, and increased plasma adiponectin by 2.4-fold. In addition, combination treatment decreased glycosylated haemoglobin by 2.2%, plasma glucose by 52%, plasma triglycerides by 77% and non-esterified fatty acids by 48%, all of which were greater than each drug alone. Combination treatment also increased expression of insulin and pancreatic and duodenal homeobox 1 (PDX1), maintained normal β-cell/α-cell distribution in islets and restored pancreatic insulin content to levels comparable to non-diabetic mice.

Conclusions and implications:

These results indicate that combination treatment with alogliptin and pioglitazone at an early stage of diabetes improved metabolic profiles and indices that measure β-cell function, and maintained islet structure in db/db mice, compared with either alogliptin or pioglitazone monotherapy.     

Changes in biologic and/or immunologic parameters induced by intratracheal instillation of pregnant mice with benzo(α)pyrene are potentially confounded by anesthesia

Benzo(α)pyrene (B(α)P) is a potent multiorgan carcinogen released into the atmosphere from commercial, domestic, and industrial sources. Studies using animal models have shown that giving B(α)P parenterally to pregnant animals (i.e., dams) led to increased tumor frequency and sensitivity to tumorigenesis in their progeny. The authors’ studies also showed that the progeny of the B(α)P-exposed dams displayed increased deficiencies in cell-mediated and humoral immune functions, changes among T-cell subsets in developing lymphoid tissues, and significant expression of B(α)P-7,8-dihydrodiol-9,10-epoxide (BPDE)-DNA adducts in thymic, splenic, and (fetal) liver tissues. The authors evaluated whether similar biologic/immunologic effects of B(α)P seen earlier in parenterally exposed mouse dams (and offspring) occurred if dams were exposed to B(α)P via the lungs. Pregnant dams were subjected to intratracheal instillation of B(α)P (at 1?mg/ml corn oil, 0.1?ml/instillate) beginning on day 11 of pregnancy (GD 11) and again on GDs 12 and 14. In each case, the dams were anesthetized with metofane. Other dams were left untreated (controls), anesthetized only, or anesthetized and then instilled with vehicle. Effects of the B(α)P exposures included lower dam body weights during gestation, decreased postbirth pup survival, increased pup tumor frequency, and decreased mixed-lymphocyte responses by pup lymphocytes. These studies also revealed that metofane imparted effects on the dams and progeny. These effects equaled the B(α)P treatments alone; in other instances, the metofane had no impact, and thus questions the observed biologic/immunologic effects of B(α)P induced in pregnant mice (and their progeny), which might have been confounded by use of this (or potentially other) anesthesia.