Feed contaminated with Fusarium toxins alter lymphocyte proliferation and apoptosis in primiparous sows during the perinatal period

Two groups of pregnant primiparous sows (day 89 ± 2 of gestation) were 54 days (±1 day) fed either with an experimental diet (5.08 mg kg⁻¹ deoxynivalenol – DON, 0.09 mg kg⁻¹ zearalenone and 21.61 mg kg⁻¹ fusaric acid) or control diet (0.25 mg kg⁻¹ DON). The consummation of feed was significantly higher in the control group. Lymphocyte stimulation in culture from peripheral blood lymphocytes (PBL) was measured by BrdU incorporation test using two different concentrations of mitogen PHA 10 and 20 μg ml⁻¹, two different concentrations of DON (5 and 1 μg ml⁻¹) and a combination of both, PHA and DON (PHA 10 + DON 5, PHA 10 + DON 1 and PHA 10 + DON 0.1 μg ml⁻¹). The lymphocyte proliferation, except for PHA 10 μg ml⁻¹, was significantly higher in the experimental group. Further on, using the photometric enzyme immunoassay, the apoptosis was studied in non-stimulated 72 h lymphocyte culture or stimulated with 1 μg ml⁻¹ of DON. The significantly higher apoptosis was in non-stimulated lymphocyte cultures from the experimental group (P = 0.036). The results suggest that such feed may affect the peripheral lymphocyte population in the direction of their proliferation response and programmed cell death.     

Infection by mycotoxigenic fungal species and mycotoxin contamination of maize grain in Umbria, central Italy

Surveys were carried out in 2006 and 2007 in Umbria (central Italy) to evaluate the presence of mycotoxigenic fungi and mycotoxins in maize grain sampled at harvest. Fusarium spp., were the most abundant species detected in maize kernels, followed by Aspergillus species of sections Flavi and Nigri and by Penicillium spp. Among Fusarium species, F. verticillioides was the most prevalent species, as detected by PCR directly on the kernels and on the fungi isolated from the kernels, followed by F. proliferatum and F. subglutinans. Fumonisins were the predominant mycotoxins with values, on average, of 4.3 and 5.7 mg kg⁻¹, in 2006 and 2007, respectively, with a maximum of 76.3 mg kg⁻¹ in the second year. Deoxynivalenol ranged from 0.2 to 3.98 mg kg⁻¹ in 2006 (average 1.04 mg kg⁻¹) and from undetectable levels to 14 mg kg⁻¹ in 2007 (average 0.86 mg kg⁻¹). Aflatoxins, analyzed only in 2007, averaged 26.3 μg kg⁻¹, with a maximum of 820 μg kg⁻¹. Zearalenone content was always very low. Results indicate that EU legal limits for these mycotoxins were rarely exceeded with low levels across most of the examined area, suggesting that this region could be considered suitable for the production of healthy maize.     

Assessment of the estrogenic activities of chickpea (Cicer arietinum L) sprout isoflavone extract in ovariectomized rats

Aim:

Chickpea (Cicer arietinum L) is a traditional Uighur herb. In this study we investigated the estrogenic activities of the isoflavones extracted from chickpea sprouts (ICS) in ovariectomized rats.

Methods:

Ten-week-old virgin Sprague-Dawley female rats were ovariectomized (OVX). The rats were administered via intragastric gavage 3 different doses of ICS (20, 50, or 100 mg·kg⁻¹·d⁻¹) for 5 weeks. Their uterine weight and serum levels of 17β-estradiol (E₂), follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured. The epithelial height, number of glands in the uterus, and number of osteoclasts in the femur were histologically quantified, and the expression of proliferating cell nuclear antigen (PCNA) was assessed immunohistochemically. Bone structural parameters, including bone mineral density (BMD), bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) were measured using Micro-CT scanning.

Results:

Treatments of OVX rats with ICS (50 or 100 mg·kg⁻¹·d⁻¹) produced significant estrogenic effects on the uteruses, including the increases in uterine weight, epithelial height and gland number, as well as in the expression of the cell proliferation marker PCNA. The treatments changed the secretory profile of ovarian hormones and pituitary gonadotropins: serum E₂ level was significantly increased, while serum LH and FSH levels were decreased compared with the vehicle-treated OVX rats. Furthermore, the treatments significantly attenuated the bone loss, increased BMD, BV/TV and Tb.Th and decreased Tb.Sp and the number of osteoclasts. Treatment of OVX rats with the positive control drug E₂ (0.25 mg·kg⁻¹·d⁻¹) produced similar, but more prominent effects.

Conclusion:

ICS exhibits moderate estrogenic activities as compared to E₂ in ovariectomized rats, suggesting the potential use of ICS for the treatment of menopausal symptoms and osteoporosis caused by estrogen deficiency.     

INVOLVEMENT OF PACAP IN ACID-INDUCED HCO3RESPONSE IN RAT DUODENUMS

Pituitary adenylate cyclase activating polypeptides (PACAP) stimulate duodenal HCO₃⁻secretion in the rat. The present study was performed to determine whether endogenous PACAP is involved in the mechanism of acid-induced HCO₃⁻response in the duodenum, using a PACAP antagonist, PACAP6-27. Under urethane anaesthetised conditions, a duodenal loop that was made between the pylorus and the area just above the outlet of the common bile duct was perfused with saline, and the HCO₃⁻secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mmHCl. Duodenal HCO₃⁻secretion was significantly stimulated by i.v. administration of PACAP-27 (8 nmol kg⁻¹) as well as vasoactive intestinal polypeptide (VIP: 8 nmol kg⁻¹). The effect of PACAP-27 (8 nmol kg⁻¹) was equivalent to that induced by prostaglandin E₂(300 μg kg⁻¹, i.v.) and significantly suppressed by either PACAP6-27 (40 nmol kg⁻¹, i.v.) or VIP antagonist (Ac-Tyr¹,d-Phe²-VIP: 40 nmol kg⁻¹, i.v.). These peptide antagonists suppressed duodenal HCO₃⁻secretory response to VIP but did not have any effect on either basal or PGE₂-stimulated HCO₃⁻secretion. On the other hand, the duodenal mucosa responded to acidification by increasing HCO₃⁻secretion in a indomethacin-sensitive manner, and this process was also significantly suppressed by both PACAP6-27 and VIP-antagonist. Duodenal damage induced by acid perfusion (100 mmHCl for 4 h) was significantly worsened by PACAP6-27, VIP antagonist as well as indomethacin at the doses that suppressed acid-induced HCO₃⁻secretion. These findings suggest that PACAP may play a role in local modulation of the duodenal mucosal integrity, by mediating the HCO₃⁻secretory response induced by mucosal acidification.     

Chromium(III) propionate complex supplementation improves carbohydrate metabolism in insulin-resistance rat model

The purpose of this study was to evaluate the antidiabetic potential and safety of the chromium(III) propionate complex (CrProp) in insulin resistance induced by a high-fructose diet in rats. The experiment was carried out on 32 nine-week old male Wistar rats divided into 4 groups of 8 rats each. Animals were fed at libitum: the control diet (AIN-93M), and high-fructose diets (HF) containing various levels of Cr(III) given as CrProp (1 mg Cr kg⁻¹ diet (HF) and supplemented with 10 mg Cr kg⁻¹ diet (HFCr10), or 50 mg Cr kg⁻¹ diet (HFCr50), equal to approx. 0.1, 1 and 5 mg kg⁻¹ body mass per day) for 8 weeks.     

Gabapentin (neurontin) and S-(+)-3-isobutylgaba represent a novel class of selective antihyperalgesic agents

1. Gabapentin (neurontin) is a novel antiepileptic agent that binds to the α₂δ subunit of voltage-dependent calcium channels. The only other compound known to possess affinity for this recognition site is the (S)-(+)-enantiomer of 3-isobutylgaba. However, the corresponding (R)-(−)-enantiomer is 10 fold weaker. The present study evaluates the activity of gabapentin and the two enantiomers of 3-isobutylgaba in formalin and carrageenan-induced inflammatory pain models.
2. In the rat formalin test, S-(+)-3-isobutylgaba (1–100 mg kg⁻¹) and gabapentin (10–300 mg kg⁻¹) dose-dependently inhibited the late phase of the nociceptive response with respective minimum effective doses (MED) of 10 and 30 mg kg⁻¹, s.c. This antihyperalgesic action of gabapentin was insensitive to naloxone (0.1–10.0 mg kg⁻¹, s.c.). In contrast, the R-(−)-enantiomer of 3-isobutylgaba (1–100 mg kg⁻¹) produced a modest inhibition of the late phase at the highest dose of 100 mg kg⁻¹. However, none of the compounds showed any effect during the early phase of the response.
3. The s.c. administration of either S-(+)-3-isobutylgaba (1–30 mg kg⁻¹) or gabapentin (10–100 mg kg⁻¹), after the development of peak carrageenan-induced thermal hyperalgesia, dose-dependently antagonized the maintenance of this response with MED of 3 and 30 mg kg⁻¹, respectively. Similar administration of the two compounds also blocked maintenance of carrageenan-induced mechanical hyperalgesia with MED of 3 and 10 mg kg⁻¹, respectively. In contrast, R-(−)-3-isobutylgaba failed to show any effect in the two hyperalgesia models.
4. The intrathecal administration of gabapentin dose-dependently (1–100 μg/animal) blocked carrageenan-induced mechanical hyperalgesia. In contrast, administration of similar doses of gabapentin into the inflamed paw was ineffective at blocking this response.
5. Unlike morphine, the repeated administration of gabapentin (100 mg kg⁻¹ at start and culminating to 400 mg kg⁻¹) over 6 days did not lead to the induction of tolerance to its antihyperalgesic action in the formalin test. Furthermore, the morphine tolerance did not cross generalize to gabapentin. The s.c. administration of gabapentin (10–300 mg kg⁻¹), R-(−) (3–100 mg kg⁻¹) or S-(+)-3-isobutylgaba (3–100 mg kg⁻¹) failed to inhibit gastrointestinal motility, as measured by the charcoal meal test in the rat. Moreover, the three compounds (1–100 mg kg⁻¹, s.c.) did not generalize to the morphine discriminative stimulus. Gabapentin (30–300 mg kg⁻¹) and S-(+)-isobutylgaba (1–100 mg kg⁻¹) showed sedative/ataxic properties only at the highest dose tested in the rota-rod apparatus.
6. Gabapentin (30–300 mg kg⁻¹, s.c.) failed to show an antinociceptive action in transient pain models. It is concluded that gabapentin represents a novel class of antihyperalgesic agents.

     

In vivo profiling of DPP4 inhibitors reveals alterations in collagen metabolism and accumulation of an amyloid peptide in rat plasma

Dipeptidyl peptidase 4 (DPP4) inhibitors represent a novel class of oral anti-hyperglycemic agents. The complete pharmacological profile of these protease inhibitors remains unclear. In order to gain deeper insight into the in vivo effects caused by DPP4 inhibition, two different DPP4 inhibitors (vildagliptin and AB192) were analyzed using differential peptide display. Wistar rats were treated with the DPP4 inhibitors (0.3 mg kg⁻¹; 1 mg kg⁻¹ or 3 mg kg⁻¹ body weight) and DPP4 activity was measured before and at the end of the experiment. One hour after compound administration, blood plasma samples were collected to generate peptide displays and to subsequently identify differentially regulated peptides. A dose-dependent decrease in blood plasma DPP4 activity was measured for both inhibitors. DPP4 inhibition influenced collagen metabolism leading to depletion of collagen derived peptides (e.g. collagen alpha 1 (III) 521-554) and accumulation of related N-terminally extended collagen derived peptides (e.g. collagen alpha 1 (III) 519-554). Furthermore, the intact amyloid rat BRI (1-23) peptide was detected in plasma following in vivo DPP4 inhibition. DPP4 catalyzed cleavage kinetics of the BRI peptide were determined in vitro. The k_cat and K_m for cleavage by DPP4 were 5.2 s⁻¹ and 14 μM, respectively, resulting in a specificity constant k_cat/K_m of 0.36 × 10⁶ s⁻¹ M⁻¹. Our results demonstrate that differential peptide analysis can be applied to monitor action of DPP4 inhibition in blood plasma. For the first time effects on basal collagen metabolism following DPP4 inhibition in vivo were demonstrated and the BRI amyloid peptide was identified as a novel DPP4 substrate.     

Investigation of the SSRI augmentation properties of 5-HT(2) receptor antagonists using in vivo microdialysis

Recent evidence that 5-HT₂ receptors exert a negative influence on central 5-hydroxytryptamine (5-HT) neurones suggests that 5-HT₂ receptor antagonists may augment the effects of serotonin selective reuptake inhibitors (SSRIs). The present study investigated whether pre-treatment with 5-HT₂ receptor antagonists enhances the effect of SSRI administration on hippocampal extracellular 5-HT of freely moving rats. Administration of the SSRI citalopram at a low (2 mg kg⁻¹) and higher (4 mg kg⁻¹) dose, increased dialysate 5-HT by 5- and 8-fold, respectively. Pre-treatment with the 5-HT₂ receptor antagonist ketanserin (4 mg kg⁻¹) augmented the effect of 4 mg kg⁻¹ but not 2 mg kg⁻¹ citalopram. The effect of 4 mg kg⁻¹ citalopram was also augmented by pre-treatment with either the 5-HT_2C receptor antagonist SB 242084 (0.5 mg kg⁻¹) or the 5-HT_2A receptor antagonist MDL 100907 (0.5 mg kg⁻¹). As with citalopram, fluoxetine elevated dialysate 5-HT at both a low (5 mg kg⁻¹) and higher (20 mg kg⁻¹) dose. However, neither dose of fluoxetine was augmented by ketanserin (4 mg kg⁻¹). These results confirm recent findings that 5-HT₂ receptor antagonists augment the effect of citalopram on extracellular 5-HT, and indicate the involvement of 5-HT_2C and possibly 5-HT_2A receptors. The lack of augmentation of fluoxetine might reflect the intrinsic 5-HT₂ receptor antagonist properties of this drug.     

Chronic blockade of angiotensin AT1 receptors improves cardinal symptoms of metabolic syndrome in diet-induced obesity in rats

Background and Purpose

AT₁ receptor antagonists decrease body weight gain in models of murine obesity. However, fewer data are available concerning the anti-obesity effects of these antagonists, given as a treatment after obesity had been established.

Experimental Approach

In spontaneously hypertensive rats, obesity was established by cafeteria diet (CD) feeding for 19 weeks. Rats were then were treated with telmisartan (8 mg·kg⁻¹·d⁻¹) or amlodipine (10 mg·kg⁻¹·d⁻¹; serving as blood pressure control) or telmisartan + amlodipine (2 + 10 mg·kg⁻¹·d⁻¹; to control for dose-dependency) for 17 weeks. Rats receiving only chow (C_chow) or CD-fed rats treated with vehicle (C_CD) served as controls.

Key Results

The CD feeding induced obesity, hyperphagia, hyperlipidaemia, and leptin and insulin resistance. Telmisartan reduced the CD-induced increase in body weight and abdominal fat mass. Whereas energy intake was higher rather than lower, the respiratory ratio was lower. After telmisartan, leptin-induced energy intake was reduced and respiratory ratio was increased compared with C_CD rats. Telmisartan also decreased plasma levels of triglycerides, free fatty acids and low-density lipoprotein. Amlodipine alone or the combination telmisartan + amlodipine did not affect body weight and eating behaviour. Telmisartan, but not amlodipine and telmisartan + amlodipine, improved glucose utilization. The decrease in BP reduction was almost the same in all treatment groups.

Conclusions and Implications

Telmisartan exerted anti-obesity effects and restored leptin sensitivity, given as a treatment to rats with obesity. Such effects required high doses of telmisartan and were independent of the decrease in blood pressure.     

The kinetics of cohesive powder de-agglomeration from three inhaler devices

Purpose

The purpose of the current investigation is to understand the kinetics of de-agglomeration (k_d) of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30-180 l min⁻¹) from three dry powder inhaler devices (DPIs), Rotahaler^® (RH), Monodose Inhaler^® (MI) and Handihaler^® (HH).

Results

Cumulative fine particle mass vs. time profiles were obtained from the powder concentration, emitted mass and volume percent <5.4 μm, embedded in the particle size distributions of the aerosol at specific times. The rate of de-agglomeration (k_d), estimated from non-linear least squares modelling, increased with increasing air flow rates. The k_dvs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k_d was highest from RH and lowest from MI. Differences in k_d between the devices were related to device mode of operation while the differences between the materials were due to the powder bed structure.

Conclusion

This approach provided a methodology to measure the rate constant for cohesive powder de-agglomeration following aerosolisation from commercial devices and an initial understanding of the influence of device, air flow rate and material on these rate constants.     

Role of α1- and β3-adrenoceptors in the modulation by SR59230A of the effects of MDMA on body temperature in the mouse

Background and purpose:

We have investigated the ability of the β₃-adrenoceptor antagonist 1-(2-ethylphenoxy)-3-[[(1S)-1,2,3,4,-tetrahydro-1-naphthalenyl]amino]-(2S)-2-propanol hydrochloride (SR59230A) to affect the hyperthermia produced by methylenedioxymethamphetamine (MDMA) in conscious mice and whether α₁-adrenoceptor antagonist actions are involved.

Experimental approach:

Mice were implanted with temperature probes under anaesthesia, and allowed 2 week recovery. MDMA (20 mg·kg⁻¹) was administered subcutaneously 30 min after vehicle or test antagonist and effects on body temperature monitored by telemetry.

Key results:

Following vehicle, MDMA produced a slowly developing hyperthermia, reaching a maximum increase of 1.8°C at 130 min post injection. A low concentration of SR59230A (0.5 mg·kg⁻¹) produced a small but significant attenuation of the slowly developing hyperthermia to MDMA. A high concentration of SR59230A (5 mg·kg⁻¹) revealed a significant and marked early hypothermic reaction to MDMA, an effect that was mimicked by the α₁-adrenoceptor antagonist prazosin. Functional and ligand binding studies revealed actions of SR59230A at α₁-adrenoceptors.

Conclusions and implications:

1-(2-ethylphenoxy)-3-[[(1S)-1,2,3,4,-tetrahydro-1-naphthalenyl]amino]-(2S)-2-propanol hydrochloride in high concentrations modulates the hyperthermic actions of MDMA in mice in two ways: by blocking an early α₁-adrenoceptor-mediated component to reveal a hypothermia, and by a small attenuation of the later hyperthermic component which may possibly be β₃-adrenoceptor-mediated (this seen with the low concentration of SR59230A). Hence, the major actions of SR59230A in modulating the actions of MDMA on temperature involve α₁-adrenoceptor antagonism.     

Long-term dietary isoflavone exposure enhances estrogen sensitivity of rat uterine responsiveness mediated through estrogen receptor α

The outcome of long-term exposure to dietary isoflavones on estrogen sensitive tissues is discussed controversially. We performed a study on tissue specific effects of lifelong isoflavone exposure on the rat uterus with exposure being initiated prenatally. We compare the effects of the dietary isoflavones, genistein (GEN) and daidzein, or GEN alone to those of isoflavone free diet. Therefore, one group received a phytoestrogen-free diet (PE-free), one an isoflavone-high diet (ISO-high) and one the PE-free diet supplemented with GEN (GEN-rich) throughout their whole lifetime. In ovariectomized adult females a uterotrophic assay was performed, comparing 17β-estradiol, GEN and two estrogen receptor subtype-specific agonists.     

Persistence and effects of rotenone on oil quality in two Italian olive cultivars

The aims of this work are to assess the persistence of rotenone in oil and drupes of olive plants of cultivars Nocellara del Belice (NB) and Cassanese (CA), and to compare the quality of oils from rotenone-treated and untreated plants. Samples of drupes and oil were analyzed at 2, 12, 22 and 30 days after treatment. Rotenone levels in drupes of treated plants declined by about 50% after 22 days from treatment (0.037 mg kg⁻¹ in NB and 0.039 mg kg⁻¹ in CA), whereas the respective values in the oil were higher (0.209 mg kg⁻¹ in NB and 0.229 mg kg⁻¹ in CA) and had a lower decay half-life (4.02 days in NB and 4.71 days in CA). For both cultivars, no significant differences in oil physicochemical and nutritional parameters were found between the two treatments. The panel test of oils extracted after 22 days did not reveal significant differences in unpleasant aromatic notes nor defects between the two treatments. Our results confirm that serious doubts remain about the safety and healthiness of oils extracted from drupes treated with rotenone. This information could assess the real risk in the use of this product for plant protection in olive growing.     

The role of α2-adrenoceptor antagonism in the anti-cataleptic properties of the atypical neuroleptic agent,clozapine, in the rat

1. The mechanism underlying the anticataleptic properties of the atypical neuroleptic agent, clozapine, has been investigated in the rat.
2. The close structural analogues of clozapine, loxapine (0.1 mg kg⁻¹ s.c.) and iso-clozapine (1 and 3 mg kg⁻¹ s.c.) induced catalepsy in rats. In contrast, clozapine and the regio-isomer of loxapine, iso-loxapine (up to 10 mg kg⁻¹ s.c.) did not produce catalepsy, but at a dose of 1 mg kg⁻¹ significantly inhibited catalepsy induced by loxapine (0.3 mg kg⁻¹ s.c.).
3. Radioligand binding assays showed that cataleptogenic potential was most clearly predicted by the D₂/5-HT_1A, D₂/5-HT_1B/1D and D₂/α₂-receptor affinity (K_D) ratios: i.e. 30–100-fold higher ratios were calculated for loxapine and iso-clozapine, whereas the ratios were less than 1 for clozapine and iso-loxapine. The ratios of affinities for D₂ to 5-HT_2A, 5-HT_2C or D₁ did not reflect the grouping of cataleptic and non-cataleptic compounds.
4. Co-treatment with the α₂-adrenoceptor antagonists, yohimbine (1–10 mg kg⁻¹ s.c.), RX 821002 (1–10 mg kg⁻¹ s.c.) and MK-912 (0.3 and 1 mg kg⁻¹ s.c.) dose-dependently inhibited the cataleptic response to loxapine (0.3 mg kg⁻¹). Yohimbine (1–10 mg kg⁻¹ s.c.) also dose-dependently inhibited the cateleptic response to haloperidol (0.3 mg kg⁻¹ s.c.). The α₂-adrenoceptor antagonists had no effect per se.
5. Neither yohimbine (10 mg kg⁻¹) nor RX821002 (3 mg kg⁻¹) altered the cataleptic response to the D₁ receptor antagonist, SCH 23390 (1 mg kg⁻¹ s.c.), while, like clozapine, both compounds abolished the response to the 5-HT_2A receptor antagonist, MDL 100,151 (3 mg kg⁻¹ s.c.).
6. The present data strongly implicate α₂-adrenoceptor blockade in the anticataleptic properties of clozapine and suggest that its lack of extrapyramidal side effects in the clinic may also be a consequence of this property.

     

Low trans structured fat from flaxseed oil improves plasma and hepatic lipid metabolism in apo E mice

The objective of this study was to explicate the effects of feeding low trans structured fat from flaxseed oil (LF) on plasma and hepatic lipid metabolism involved in apo E^−/− mice. The animals were fed a commercial shortening (CS), commercial low trans fat (CL) and LF diet based on AIN-76 diet (10% fat) for 12 weeks. LF supplementation exerted a significant suppression in hepatic lipid accumulation with the concomitant decrease in liver weight. The LF significantly lowered plasma total cholesterol and free fatty acid whereas it significantly increased HDL-C concentration and the HDL-C/total-C ratio compared to the CS group. Reduction of hepatic lipid levels in the LF group was related with the suppression of hepatic enzyme activities for fatty acid and triglyceride synthesis, and cholesterol regulating enzyme activity compared to the CS and CL groups. Accordingly, low trans structured fat from flaxseed oil is highly effective for improving hyperlipidemia and hepatic lipid accumulation in apo E^−/− mice.     

Cue-conditioned alcohol seeking in rats following abstinence: involvement of metabotropic glutamate 5 receptors

Background and purpose:

The current study was designed to: (i) examine whether functional interactions occur between receptors known to regulate alcohol self-administration; and (ii) characterize relapse to alcohol seeking following abstinence.

Experimental approach:

The selective cannabinoid CB₁ receptor antagonist SR141716A (0.03–1.0 mg·kg⁻¹ i.p.) resulted in a dose-dependent reduction in ethanol self-administration in ethanol-preferring Indiana-preferring rats. SR141716A was then co-administered with either the selective glutamate metabotropic glutamate 5 (mGlu₅) receptor antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) or the selective adenosine A_2A receptor antagonist {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304","term_text":"SCH58261"}}SCH58261.

Key results:

When administered at individually sub-threshold doses, a combination of SR141716A (0.1 mg·kg⁻¹) and {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304","term_text":"SCH58261"}}SCH58261 (0.5 mg·kg⁻¹ i.p.) produced a reduction (28%) in ethanol self-administration. Combinations of threshold doses of SR141716A (0.3 mg·kg⁻¹) and {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304","term_text":"SCH58261"}}SCH58261 (2.0 mg·kg⁻¹, i.p.) caused an essentially additive reduction (68%) in alcohol self-administration. A combination of individually sub-threshold doses of CB₁ and mGlu₅ receptor antagonists did not affect alcohol self-administration; however, combined threshold doses of SR141716A (0.3 mg·kg⁻¹) and MTEP (1.0 mg·kg⁻¹ i.p.) did reduce ethanol self-administration markedly (80%). Cue-conditioned alcohol seeking was attenuated by pretreatment with MTEP (1.0 mg·kg⁻¹) co-administered with SR141716A (0.3 mg·kg⁻¹ i.p.). In contrast, {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304","term_text":"SCH58261"}}SCH58261 (2.0 mg·kg⁻¹) co-administered with SR141716A (0.3 mg·kg⁻¹ i.p.) did not reduce cue-conditioned alcohol seeking.

Conclusions and implications:

Adenosine A_2A and cannabinoid CB₁ receptors regulated alcohol self-administration additively, but combined low-dose antagonism of these receptors did not prevent cue-conditioned alcohol seeking after abstinence. In contrast, combined low-dose antagonism of mGlu₅ and CB₁ receptors did prevent relapse-like alcohol seeking after abstinence, suggesting a prominent role for mGlu₅ receptors in this paradigm.     

Reproductive toxicity of methomyl insecticide in male rats and protective effect of folic acid

The acute toxicity (LD₅₀) of insecticide methomyl and its effects on male reproduction in rats were carried out. Methomyl was given orally to male rats daily for 65 successive days at two doses (0.5 and 1.0 mg kg⁻¹ b.wt., corresponding to 1/40 and 1/20 LD₅₀) alone and in combination with folic acid (1.1 mg kg⁻¹ b.wt., corresponding to acceptable daily intake, ADI). Fertility index, weight of sexual organs, semen picture, serum testosterone level and histopathology of testes were the parameters used to evaluate the reproductive efficiency of treated rats. The reversibility of methomyl effects was also studied after 65 days post-administration. The oral LD₅₀ of methomyl was 20.0 mg kg⁻¹ b.wt. in male rats. Methomyl significantly decreased the fertility index, weight of testes and accessory male sexual glands, serum testosterone level and sperm motility and count, but increased sperm cell abnormality. It induced testicular lesions characterized by moderate to severe degenerative changes of seminiferous tubules and incomplete arrest of spermatogenesis. These toxic effects were not persistent (reversible). Coadministration of folic acid with methomyl decreased its reproductive toxicity. A great attention should be taken during field application of methomyl to avoid its deleterious effects in farm animals and occupationally exposed humans.     

Safety and efficacy of Zingiber officinale roots on fertility of male diabetic rats

The acute toxicity of methanolic and watery extracts of Zingiber officinale (ZO) roots in mice and their effects on fertility of male diabetic rats were carried out. The fertility experiment was done on six groups of male rats one of them was kept as normal control, while the others were rendered diabetic by subcutaneous injection of alloxan (120 mg kg⁻¹). One group was left as diabetic control, while the others were given orally either methanolic (100 and 200 mg kg⁻¹) or watery extract (150 and 300 mg kg⁻¹) for 65 consecutive days. The results showed that no mortalities occur when both extracts were given orally to mice in doses up to 5 g kg⁻¹ b.wt. Both extracts increased fertility index, sexual organs weight, serum testosterone level and sperm motility and count. Histopathological examination of the testes of diabetic rats showed mild to moderate degenerative changes of spermatogenic cells, diffuse edema and incomplete arrest of spermatogenesis. Treatment with ZO extracts caused alleviation of the testicular lesions that appeared in non-treated diabetic rats. Conclusively, extracts of ZO have high safety in mice and intake of ZO roots as a drink may be useful for diabetic patients who suffer from sexual impotency.     

Effects of bisphenol A on the proliferation and cell cycle of HBL-100 cells

Bisphenol A (BPA) is an environmental estrogen that exhibits non-genotoxic carcinogenicity, causing concern globally. The aim was to investigate the effects of BPA on the proliferation and cell cycle of human normal breast cells HBL-100. An improved E-Screen assay was used to study cell proliferation, and flow cytometry was used to study cell cycle phases. Western blot analysis was utilized to detect cell cycle proteins and estrogen receptor α (ERα) expression. The results showed that the highest cell proliferation rate induced by BPA was at 1.0 × 10⁻⁶ mol/L. At 1.0 × 10⁻¹⁰, 1.0 × 10⁻⁸, and 1.0 × 10⁻⁶ mol/L, BPA promoted more cells to enter into G2/M phase and caused an increase in the expression of cyclinD1 and CDK4. After adding ICI182780 into the system, the promoting effects of BPA on cell proliferation and cell cycle change decreased, but these promoting effects were still significantly greater compared with the solvent control (P < 0.05). Regardless of ICI182780 exposure, BPA did not have significant effect on ERα expression. BPA has estrogen-like activity and can stimulate HBL-100 proliferation and cell division through the estrogen receptor pathway. BPA may have other pathways through which it can exert stimulating effects and exhibit non-genotoxic carcinogenicity.     

Investigation of the mechanisms underlying the hypophagic effects of the 5-HT and noradrenaline reuptake inhibitor,sibutramine, in the rat

1. Sibutramine is a novel 5-hydroxytryptamine (5-HT) and noradrenaline reuptake inhibitor (serotonin- noradrenaline reuptake inhibitor, SNRI) which is currently being developed as a treatment for obesity. Sibutramine has been shown to decrease food intake in the rat. In this study we have used a variety of monoamine receptor antagonists to examine the pharmacological mechanisms underlying sibutramine-induced hypophagia.
2. Individually-housed male Sprague-Dawley rats were maintained on reversed phase lighting with free access to food and water. Drugs were administered at 09 h 00 min and food intake was monitored over the following 8 h dark period.
3. Sibutramine (10 mg kg⁻¹, p.o.) produced a significant decrease in food intake during the 8 h following drug administration. This hypophagic response was fully antagonized by the α₁-adrenoceptor antagonist, prazosin (0.3 and 1 mg kg⁻¹, i.p.), and partially antagonized by the β₁-adrenoceptor antagonist, metoprolol (3 and 10 mg kg⁻¹, i.p.) and the 5-HT receptor antagonists, metergoline (non-selective; 0.3 mg kg⁻¹, i.p.); ritanserin (5-HT_2A/2C; 0.1 and 0.5 mg kg⁻¹, i.p.) and SB200646 (5-HT_2B/2C; 20 and 40 mg kg⁻¹, p.o.).
4. By contrast, the α₂-adrenoceptor antagonist, RX821002 (0.3 and 1 mg kg⁻¹, i.p.) and the β₂-adrenoceptor antagonist, ICI 118,551 (3 and 10 mg kg⁻¹, i.p.) did not reduce the decrease in food intake induced by sibutramine.
5. These results demonstrate that β₁-adrenoceptors, 5-HT_2A/2C-receptors and particularly α₁-adrenoceptors, are involved in the effects of sibutramine on food intake and are consistent with the hypothesis that sibutramine-induced hypophagia is related to its ability to inhibit the reuptake of both noradrenaline and 5-HT, with the subsequent activation of a variety of noradrenaline and 5-HT receptor systems.