Dopamine D2 Receptor Gene Expression in Rat Lines Selected for Differences in Voluntary Alcohol Consumption

A selective breeding program has led to the establishment of the alcohol-preferring AA (Alko, Alcohol) and alcohol-avoiding ANA (Alko, Nonalcohol) rat lines. To reveal putative baseline differences in dopamine receptor gene expression and dopamine receptor binding profile in the AA and ANA rat lines, we assessed striatal D₂ mRNA levels in these two rat lines. Autoradiographical studies on dopamine D₁ and D₂ receptors in the striatum and nucleus accumbens were also performed with [³H]SCH 23390 and [¹²⁵I]iodosulpiride/[³H]spiperone, respectively. The baseline differences in D₁ or D₂ receptor binding and D₂ receptor gene expression between AA and ANA rat lines are marginal, and are not likely to play a role in the genetic background of the differential alcohol drinking behavior of these rat lines.     

Estrogen-Dependent Enhancement of NO Production in the Nucleus Tractus Solitarius Contributes to Ethanol-Induced Hypotension in Conscious Female Rats

Background:  Our previous pharmacological and cellular studies showed that peripheral (cardiac and vascular) nitric oxide synthase (NOS)-derived NO is implicated in the estrogen (E₂)-dependent hypotensive action of ethanol in female rats. The objective of this study was to test the hypothesis that enhanced NO production in the nucleus tractus solitarius (NTS) is implicated in the E₂-dependent hypotensive action of ethanol.
Methods:  To achieve this goal, we utilized in vivo electrochemistry to measure real time changes in neuronal NO to investigate the acute effects of intragastric ethanol (0, 0.5, or 1 g/kg) on NO in NTS neurons, blood pressure (BP), and heart rate (HR) in conscious female rats in the absence (ovariectomized, OVX, rats) or presence of E₂.
Results:  In sham operated (SO) rats, ethanol elicited dose-related increase in NTS NO and reduction in BP. These neurochemical and BP effects of ethanol were absent in OVX rats. Whether the neurochemical effect of ethanol and the associated hypotension are dependent on rapid E₂ signaling was investigated. In OVX rats pretreated, 30 minutes earlier, with E₂ (1 μg/kg), intragastric ethanol (1 g/kg) increased NTS NO and reduced BP and these responses were comparable to those obtained in SO rats.
Conclusions:  The present findings suggest that increased production of NO in NTS neurons contributes to ethanol-evoked hypotension in female rats. Further, ethanol enhancement of neuronal NO production in the brainstem is dependent on rapid E₂ signaling.     

The reinforcing properties of salsolinol in the ventral tegmental area: evidence for regional heterogeneity and the involvement of serotonin and dopamine

Background:  Salsolinol (SAL), the condensation product of acetaldehyde and dopamine, may be a factor contributing to alcohol abuse. Previous research indicated that both ethanol and acetaldehyde are self-administered into the posterior ventral tegmental area (VTA). The current study examined SAL self-infusions into the VTA, and determined the involvement of dopamine neurons and 5-HT₃ receptors in this process.
Methods:  The intracranial self-administration technique was used to determine the self-infusion of SAL into the VTA of adult, male Wistar rats. The rats were placed in 2-lever (active and inactive) experimental chambers, and allowed to respond for the self-infusion of 0, 0.03, 0.1, 0.3, 1.0 or 3.0 μM SAL into the posterior or anterior VTA. In a second experiment, rats self-administered 0.3 μM SAL for the initial 4 sessions, co-administered SAL with ICS-205,930 (a 5-HT₃ receptor antagonist) or quinpirole (a D_2,3 receptor agonist) for sessions 5 and 6, and then only 0.3 μM SAL for session 7.
Results:  Wistar rats, given 0.03 to 0.3 μM SAL, received more infusions per session than did the group given artificial cerebrospinal fluid (aCSF) alone (e.g., 41 infusions for 0.1 μM SAL versus 9 infusions for the aCSF group), and responded more on the active than inactive lever. These effects were observed in the posterior but not in anterior VTA. Co-infusion of 100 μM ICS-205,930, or quinpirole significantly reduced self-infusions and active lever responding.
Conclusions:  SAL produces reinforcing effects in the posterior VTA of Wistar rats, and these effects are mediated by activation of DA neurons and local 5-HT₃ receptors.     

THE VITAMIN D3 METABOLITE-TYPE ACTIVITY OF SOLANUM MALACOXYLON

1. Administration of an aqueous extract of the dried leaves of Solanum malacoxylon (DLSM) to rats causes a rapid hyperphosphataemia and a decrease in plasma alkaline phosphatase activity; the two effects are typical of 1,25(OH)₂D₃, the hormonally active metabolite of vitamin D₃.
2. DLSM, like both vitamin D₃ and parathyroid hormone, increases plasma calcium and citrate levels in rats. The effect of DLSM in influencing plasma citrate, and the role of this important metabolite in mineral metabolism is discussed.
3. A decrease of plasma magnesium levels occurs in rats following treatment with DLSM. This decrease, which is associated with a renal loss of this cation, is remarkably similar to that produced by hypervitaminosis D₃.
4. Prolonged administration of DLSM to vitamin D deficient rats causes a polyuria, hypercalciuria, hyperphosphaturia, hypermagnesuria, an increase in urinary total hydroxyproline, an increase in plasma total hexosamines, and a corresponding decrease in the bone total hexosamines. These effects, some of which can also be produced by hyperparathyroidism, or following the administration of parathyroid extract (PTE), large doses of vitamin D₃, or 1,25(OH)₂D₃, suggest that DLSM, like the latter compounds, is capable of causing bone mineral mobilization, and the dissolution of bone organic matrix.     

Ethanol enhances GABAergic transmission onto dopamine neurons in the ventral tegmental area of the rat

Background:  Activation of the dopaminergic (DA) neurons of the ventral tegmental area (VTA) by ethanol has been implicated in its rewarding and reinforcing effects. At most central synapses, ethanol generally increases inhibitory synaptic transmission; however, no studies have explored the effect of acute ethanol on GABAergic transmission in the VTA.
Methods:  Whole-cell patch clamp recordings of inhibitory postsynaptic currents (IPSCs) from VTA-DA neurons in midbrain slices from young rats.
Results  Acute exposure of VTA-DA neurons to ethanol (25 to 50 mM) robustly enhanced GABAergic spontaneous and miniature IPSC frequency while inducing a slight enhancement of spontaneous IPSC (sIPSC) amplitude. Ethanol (50 mM) enhanced paired-pulse depression of evoked IPSCs, further suggesting enhanced GABA release onto VTA-DA neurons. The frequency of sIPSCs was suppressed by the GABA_B agonist, baclofen (1.25 μM) and enhanced by the antagonist, SCH50911 (20 μM); however, neither appeared to modulate or occlude the effects of ethanol on sIPSC frequency.
Conclusions:  The present results indicate that ethanol increases postsynaptic GABA_A receptor sensitivity, enhances action potential-independent GABA release onto VTA-DA neurons, and that this latter effect is independent of GABA_B auto-receptor inhibition of GABA release.     

Liposomal 1,25 (OH)2 vitamin D3 compounds block proliferation and induce differentiation in myelomonocytic leukaemia cells

The vitamin D₃ derived hormone 1,25 (OH)₂ vitamin D₃ (1,25 D₃) is able to induce growth arrest and differentiation in myelomonocytic leukaemia cells. In order to allow for specific delivery to leukaemic cells the lipophilic compound was incorporated into the lipid membranes of liposomes. Liposomal 1,25 D₃ reduced proliferation as measured by ³H-thymidine incorporation in HL60 leukaemia cells by up to 60%. When liposomes were prepared at different concentrations of 1,25 D₃ 65% inhibition was achieved at 48 n M . The MC 1288 stereoisomer of 1,25 D₃ was more potent and had the same activity at 48 n M .
The effect of the liposomal compounds was specific to myeloid cells as they reduced proliferation in myelomonocytic HL60, monoblastic U937 and monocytic Mono Mac 6 cells but not in the T-cell lines Jurkat and Molt 4.
The antiproliferative effect of liposomal 1,25 D₃ was associated with an induction of differentiation since treated HL60 cells showed a monocytic morphology, increased expression of CD14 and decreased expression of CD33.
When peripheral blood leukaemic cells from M4 and M5 acute myeloid leukaemia (AML) patients were admixed with liposomal compounds an antiproliferative effect was seen in all five cases, including the two cases where free compounds led to enhanced growth. Liposomal delivery of 1,25 (OH)₂ vitamin D₃ may offer a novel approach to treatment of myelomonocytic leukaemia.     

Influence of sex and estrogen on vitamin D-induced arterial calcification in rats

Background:   It is known that the process of arteriosclerosis is affected by sex and estrogen. The present study was thus undertaken to examine the effects of these factors on arterial calcification, a form of arteriosclerosis, using a rat model of vitamin D toxicity.
Methods and results:   Vehicle or 5 µg/kg per day 1α(OH)D₃ was given to male and female 30-week-old Fisher rats for 2 weeks. Arterial calcification, evaluated by calcium content in the aorta, was 70% more marked in male rats compared to that in female rats, whereas calcium content in the aorta was similar in vehicle-treated male and female rats. Next, the effects of ovariectomy and estrogen replacement (estradiol dipropionate 20 µg/kg per week) were examined in female rats given 5 µg/kg per day 1α(OH)D₃ for 2 weeks. Calcium content in the aorta was significantly higher in ovariectomized rats than in sham-operated rats and in ovariectomized and estrogen-replaced rats. No difference between the groups was seen when vehicle was given to the animals.
Conclusions:   These results suggest that sex and estrogen can modify the process of arterial calcification. The mechanisms remain to be determined, although the effects were independent of serum calcium level.     

The thyroid hormone derivative 3-iodothyronamine increases food intake in rodents

Background:  The thyroid hormone derivative 3-iodothyronamine (T₁AM), an endogenous biogenic amine, is a potent agonist of the G protein–coupled trace amine-associated receptor 1 (TAAR1). T₁AM is present in rat brain, and TAAR1 is expressed in hypothalamic nuclei associated with the regulation of energy homeostasis.
Aim:  The aim of this study was to determine the effects of T₁AM on food intake in rodents.
Methods:  We determined the effect of (i) intraperitoneal (i.p.) administration of T₁AM on food intake, oxygen consumption (VO₂) and locomotor activity in mice; (ii) intracerebroventricular (ICV) injection of T₁AM on food intake in male rats; (iii) c-fos expression following ventricular administration of T₁AM in male rats; and (iv) direct injection of T₁AM into the arcuate nucleus (ARC) of male rats on food intake.
Results:  (i) T₁AM (4 nmol/kg) significantly increased food intake following i.p. injection in mice but had no effect on VO₂ or locomotor activity. (ii) ICV administration of T₁AM (1.2 nmol/kg) significantly increased food intake in male rats. (iii) Intraventricular administration of T₁AM significantly increased c-fos expression in the ARC of male rats. (iv) Direct administration of T₁AM (0.12, 0.4 and 1.2 nmol/kg) into the ARC of male rats significantly increased food intake.
Conclusion:  These data suggest that T₁AM is an orexigenic factor that may act through the ARC to increase food intake in rodents.     

Emodin reverses CCl4 induced hepatic cytochrome P450 (CYP) enzymatic and ultrastructural changes: The in vivo evidence

Aim:  The curative effect of emodin (1,3,8-trihydroxy-6-methyl anthraquinone), an active compound of the plant species Ventilago maderaspatana Gaertn, was evaluated against carbon tetrachloride (CCl₄) induced hepatic cytochrome P450 (CYP) enzymatic and ultrastructural alterations in rats.
Methods:  Female rats were administered CCl₄ (1.5 mL/kg, ip) followed by varying doses of emodin (20, 30 and 40 mg/kg, oral po) after 24 h of CCl₄ administration. Animals were euthanized after 24 h of last administration to determine liver function tests in serum, hepatic light microscopic and ultrastructural changes, activity of CYP enzymes, microsomal lipid peroxidation and protein contents, hexobarbitone induced sleep time and bromosulphalein retention.
Results:  The CCl₄ induced-toxic effects were observed with sharp elevation in the release of serum transaminases, alkaline phosphatase, lactate dehydrogenase and γ-glutamyl transpeptidase. An initial study for an optimum dose of emodin among different dose levels revealed that a 30 mg/kg dose was effective in restoring all the enzymatic variables and liver histoarchitecture in a dose dependent manner. Exposure to CCl₄ diminished the activities of CYP enzymes (i.e. aniline hydroxylase and amidopyrine-N-demethylase and microsomal protein contents with concomitant increase in microsomal lipid peroxidation). Emodin at 30 mg/kg effectively reversed the CCl₄ induced hepatotoxic events, which was consistent with ultrastructural observations. Hexobarbitone-induced sleep time and plasma bromosulphalein retention also improved liver functions after emodin therapy.
Conclusion:  By reversal CYP activity and ultrastructural changes, emodin shows a strong hepatoprotective abilities.     

BK channel subunit composition modulates molecular tolerance to ethanol

Background:  The large conductance calcium-activated potassium channel (also called BK channel or Slo channels) is a well-studied target of alcohol action, and plays an important role in behavioral tolerance.
Methods:  Using patch clamp electrophysiology, we examined human BK channels expressed in HEK293 cells to test whether tolerance to ethanol occurs in excised patches and whether it is influenced by subunit composition. Three combinations were examined: hSlo, hSlo + β₁, and hSlo + β₄.
Results:  The 2 components of BK alcohol adaptation (Component 1: rapid tolerance to acute potentiation, and Component 2: a more slowly developing decrease in current density) were observed, and varied according to subunit combination. Using a 2-exposure protocol, Component 1 tolerance was evident in 2 of the 3 combinations, because it was more pronounced for hSlo and hSlo + β₄.
Conclusions:  Thus, rapid tolerance in human BK occurs in cell-free membrane patches, independent of cytosolic second messengers, nucleotides or changes in free calcium. Alcohol pretreatment for 24 hours altered subsequent short-term plasticity of hSlo + β₄ channels, suggesting a relationship between classes of tolerance. Finally, Component 2 reduction in current density showed a striking dependency on channel composition. Twenty-four hour exposure to 25 mM ethanol resulted in a down-regulation of BK current in hSlo and hSlo + β₄ channels, but not in hSlo + β₁ channels. The fact that hSlo + β₁ channels show less sensitivity to acute challenge, in conjunction with less Component 1 and Component 2 tolerance, suggests subunit composition is an important factor for these elements of alcohol response.     

Effect of Acute Ethanol Administration on the Release of Opioid Peptides From the Midbrain Including the Ventral Tegmental Area

Background:  Experimental evidence suggests that ethanol alters the activity of the endogenous opioid peptide systems in a dose and brain-region dependent manner. These alterations may influence the processes of ethanol reward and reinforcement. Thus, it was the objective of this study to investigate the response of the 3 major opioid peptide systems (endorphins, enkephalins, and dynorphins) to acute ethanol administration, at the level of the midbrain including the ventral tegmental area (midbrain/VTA), a region important for drug, including ethanol reinforcement.
Methods:  Using the in vivo microdialysis technique coupled with specific solid-phase radioimmunoassay for β-endorphin, met-enkephalin, and dynorphin A_1–8, changes in the extracellular concentration of theses peptides at the level of midbrain/VTA were determined at distinct time points following the administration of 0.0 (saline), 0.8, 1.2, 1.6, 2.0, and 2.4 g ethanol/kg B.Wt.
Results:  A biphasic effect of ethanol on β-endorphin release was found, with low to medium (1.2, 1.6, and 2.0 g) but not high (2.4 g) doses of ethanol, inducing a significant increase in the dialysate content of β-endorphin. A late increase in the dialysate content of dynorphin A_1–8 was observed in response to the 1.2 g ethanol dose. However, none of the ethanol doses tested significantly altered the content of met-enkephalin in the dialysate.
Conclusions:  The present findings suggest that the ethanol-induced increase of β-endorphin release at the level of midbrain/VTA may influence alcohol reinforcement.     

CB1 Receptor Blockade Decreases Ethanol Intake and Associated Neurochemical Changes in Fawn-Hooded Rats

Background:  This study was undertaken to identify the neurochemical changes underlying the attenuation of voluntary ethanol intake induced by the cannabinoid CB1 receptor antagonist AM251 in fawn-hooded rats.
Methods:  Rats were exposed to the 2-bottle-choice paradigm (ethanol 10% v/v or water) for 15 days. After this period, rats received AM251 (3 to 6 mg/kg, i.p.) or vehicle.
Results:  Voluntary ethanol intake decreased (30%) with the administration of incremental dosages of AM251 (3 mg/kg, 5 days and 6 mg/kg, 5 days) in rats with acquired high preferring ethanol consumption (>3.5 g of ethanol/kg/d). Ethanol intake significantly decreased proopiomelanocortin expression in the arcuate nucleus (38.31%) and μ-opioid-DAMGO-stimulated [³⁵S]-GTPγ binding in the caudate-putamen (40%), nucleus accumbens core (AccC) (32.87%), and shell (AccS) (34.21%). Moreover, ethanol intake increased tyrosine hydroxylase (TH) gene expression in the substantia nigra (24%) and ventral tegmental area (23%) and corticotrophin-releasing gene expression in the paraventricular hypothalamic nucleus (41.6%). The reduction of ethanol intake induced by AM251 was associated with blockade or significant reduction of the changes produced by ethanol in the expression of these genes in key regions related to drug dependence. Interestingly, treatment with AM251 reduced (20%) TH gene expression in rats drinking only water. In this respect, the action of AM251 in reducing TH gene expression may not be specific.
Conclusion:  Taken together, these results revealed that blockade of cannabinoid CB1 receptors (CB1r) decreased voluntary ethanol intake in ethanol-habituated rats by normalizing the neurochemical alterations induced by ethanol.     

Serum 25-hydroxyvitamin D3 is related to physical activity and ethnicity but not obesity in a multicultural workforce

Methods : Serum 25-hydroxyvitamin D₃, a marker of recent sun exposure and vitamin D status, was measured in 390 New Zealand residents (95 Pacific Islanders, 74 Maori and 221 others mostly of European descent), who were part of a larger cross-sectional survey of a workforce ( n = 5677) aged 40–64 years.
Results : Serum 25-hydroxyvitamin D₃ levels were significantly lower in Pacific Islanders (mean (SE) = 56 (3) nmol/L; p = 0.0001) and Maoris (68 (3) nmol/L; p =0.036) compared with Europeans (75 (2) nmol/L) after adjusting for age, sex and time of year. Also adjusting for ethnic group, 25-hydroxyvitamin D, was higher in people doing vigorous (aerobic) leisure physical activities (71 (2) nmol/L; p=0.0066) and moderate (non-aerobic) activities (68 (3) nmol/L; p = 0.12) compared with those who were inactive (63 (2) nmol/L). However, 25-hydroxyvitamin D₃ was unrelated to body mass index, serum lipids, blood pressure or cigarette smoking.
Background : Recent research suggests that body vitamin D levels are decreased in coronary heart disease and diabetes, but it is unclear which cardiovascular risk factors are related to vitamin D status.
Aims : To examine the relation between vitamin D status and major cardiovascular risk factors.
Conclusions : People with increased skin pigmentation, such as Polynesians, and people who are inactive, have decreased body levels of vitamin D; this might partly explain their increased risk of cardiovascular disease.     

Contribution of NADH Increases to Ethanol's Inhibition of Retinol Oxidation by Human ADH Isoforms

Background:  A decrease in retinoic acid levels due to alcohol consumption has been proposed as a contributor to such conditions as fetal alcohol spectrum diseases and ethanol-induced cancers. One molecular mechanism, competitive inhibition by ethanol of the catalytic activity of human alcohol dehydrogenase (EC 1.1.1.1) (ADH) on all-trans-retinol oxidation has been shown for the ADH7 isoform. Ethanol metabolism also causes an increase in the free reduced nicotinamide adenine dinucleotide (NADH) in cells, which might reasonably be expected to decrease the retinol oxidation rate by product inhibition of ADH isoforms.
Methods:  To understand the relative importance of these two mechanisms by which ethanol decreases the retinol oxidation in vivo we need to assess them quantitatively. We have built a model system of 4 reactions: (1) ADH oxidation of ethanol and NAD⁺, (2) ADH oxidation of retinol and NAD⁺, (3) oxidation of ethanol by a generalized Ethanol_oxidase that uses NAD⁺, (4) NADH_oxidase which carries out NADH turnover.
Results:  Using the metabolic modeling package S crum P y , we have shown that the ethanol-induced increase in NADH contributes from 0% to 90% of the inhibition by ethanol, depending on (ethanol) and ADH isoform. Furthermore, while the majority of flux control of retinaldehyde production is exerted by ADH, Ethanol_oxidase and the NADH_oxidase contribute as well.
Conclusions:  Our results show that the ethanol-induced increase in NADH makes a contribution of comparable importance to the ethanol competitive inhibition throughout the range of conditions likely to occur in vivo, and must be considered in the assessment of the in vivo mechanism of ethanol interference with fetal development and other diseases.     

Disruption of tissue-type plasminogen activator gene in mice aggravated liver fibrosis

Background and Aim:  Tissue-type plasminogen activator (tPA) is one of the major components in the matrix proteolytic network whose role in the pathogenesis of liver fibrosis remains unknown. The aim of this study is to investigate the role of tPA in carbon tetrachloride (CCl₄)-induced liver fibrosis.
Methods:  Wild-type and tPA knockout mice (8 mice per group) were injected interperitoneumly with 25% CCl₄ 2 ml/kg twice per week as CCl₄ administration groups and olive oil 2 ml/kg as controls. After 4 weeks, the livers of mice were removed under deep anesthesia and prepared for further studies such as histology, immunostaining, hydroxyproline assay, zymography and western blot analysis.
Results:  Mice lacking tPA developed more severe morphological injury and displayed an increased deposition of collagen in the liver after CCl₄ administration compared with wild-type counterparts. Deficiency of tPA increased α-smooth muscle actin expression in the mice livers. On the other hand, the decrease of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) activities, metalloproteinase-13 (MMP-13) expression and a marked increase of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) expression were found in the liver of CCl₄ administrated tPA^−/− mice compared with wild-type counterparts.
Conclusions:  Deficiency of tPA aggravated liver fibrosis through promoting hepatic stellate cells (HSCs) activation and inhibiting ECM degradation by decreasing MMP-2, MMP-9 activities and disrupting the balance between MMP-13 and TIMP-1.     

Dietary trans-resveratrol bioavailability and effect on CCl4-induced liver lipid peroxidation

Background and Aim:  Several in vitro studies have demonstrated the ability of pure trans-resveratrol (t-Res) to act as an anti-oxidant, but the scientific literature is lacking in in vivo studies dealing with dietary t-Res bioavailability in oxidative stress models. Our aim was to investigate the bioavailability of t-Res from dietary sources and its effect on an animal model of carbon tetrachloride (CCl₄)-induced liver lipid peroxidation.
Methods:  Ten rats were intragastrically administered for 14 days with a grape-stalk extract determining a daily t-Res dosage of 3 mg/kg. The control group (10 rats) was daily injected with the vehicle solvent without the t-Res extract. After 1 week, the induction of liver lipid peroxidation by CCl₄ injection was carried out. Serum and liver samples, at different time intervals, were collected to evaluate t-Res content, by high-performance liquid chromatography (HPLC) and liquid chromatography–mass spectometry–mass spectometry (LC-MS-MS). Liver malondialdehyde (MDA) as marker of oxidative stress was measured.
Results:  t-Res accumulates in the liver reaching 49.8 ± 10.2 ng/g after 7 days and 191.8 ± 15.3 ng/g after 14 days. No t-Res was detected in serum. The increase of MDA liver concentration due to CCl₄ injection after 24 h and 1 week was reduced by 38% and a 63%, respectively, by the treatment with the t-Res extract.
Conclusions:  A moderate consumption of t-Res from a dietary source resulted in a time-dose-dependent liver accumulation. It was able to counteract in vivo CCl₄-induced liver lipid peroxidation thus demonstrating the hepatoprotective property of t-Res.     

Possibility of 5-HT3 Receptor Involvement in Alcohol Dependence: A Microdialysis Study of Nucleus Accumbens Dopamine and Serotonin Release in Rats with Chronic Alcohol Consumption

The present study was performed to examine the involvement of serotonin-3 (5-HT3) receptors in the rat nucleus accumbens (ACC) in alcohol dependence. In alcohol-treated rats, perfusion of 40 mM K⁺ and 100 mM ethanol (EtOH) through the microdialysis probe increased the extracellular levels of ACC dopamine (DA), compared with controls. Perfusion of the serotonin (5-HT) uptake inhibitor sertlarine enhanced the extracellular levels of ACC 5-HT in both groups. Increased 5-HT availability in the synaptic clefts on the ACC further activated ACC DA release in the alcohol-treated rats, in comparison with controls. In the final experiments, perfusion of the 5.0 μ M 5-HT₃ receptor agonist 2-methyl-5-HT (2-Me-5-HT) through the microdialysis probe enhanced the extracellular levels of ACC DA. Magnitude of 2-Me-5-HT-induced DA release was significantly higher in alcohol-treated rats than in controls. On the other hand, 40 mM K⁺- and 100 mM EtOH-induced extracellular 5-HT release in alcohol-treated rats were markedly inhibited. These results show that (1) chronic alcohol intake increases the sensitivity of 5-HT₃ receptors, (2) 5-HT₃ receptors regulate DA release in the ACC, (3) the dopaminergic neuronal systems associated with 5-HT₃ ionophore in the ACC were upregulated after chronic alcohol exposure, and (4) chronic alcohol intake desensitizes the serotonergic neuronal systems in rat ACC. These findings suggest that neurochemical functions of 5-HT₃ receptors in regulating DA release in the ACC after alcohol exposure compensate for the dysfunction of serotonergic activity to restore the original properties in processing alcohol tolerance and that the development of alcohol dependence may be mediated by ACC 5-HT₃ receptors.     

Co-administration of SR141716 with peptide YY3-36 or oxyntomodulin has additive effects on food intake in mice

Background:  SR141716 has been shown to significantly inhibit food intake and reduce body weight by antagonizing CB₁ receptors. The gut hormones peptide YY_3–36 (PYY_3–36) and oxyntomodulin (OXM) inhibit food intake through Y₂ and Glucagon-Like-Peptide (GLP)-1 receptors respectively.
Objective:  To determine the effects of co-administration of SR141716 with either PYY_3–36 or OXM in mice on food intake.
Methods:  Mice (n = 14 per group) were fasted for 16 h prior to study days and given two intraperitoneal injections: study 1, vehicle–saline, SR141716–saline, vehicle–PYY3–36 or SR141716–PYY3–36; study 2: vehicle–saline, SR141716–saline, vehicle–OXM or SR141716–OXM.
Food was returned and measured following injections.
Results:  Co-administration of SR141716–PYY_3–36 or SR141716–OXM showed greater inhibition in food intake when compared with administration of SR141716, PYY_3–36 or OXM alone.
Conclusion:  Our data show that SR141716 in combination with PYY_3–36 or OXM reduces food intake additively in mice.     

Levothyroxine (LT4) suppression treatment for benign thyroid nodules alters coagulation

Objective  Endogenous hyperthyroidism is associated with altered coagulation. The aim of the present study is to investigate the effect of levothyroxine (LT₄) suppression treatment for benign thyroid nodules on coagulation system.
Design  Prospective case-control study.
Patients  Thirty consecutive euthyroid pre-menopausal women with nodular goitre disease and 28 healthy controls were included in the study.
Measurements  Plasma fibrinogen, d-dimer, von Willebrand factor (vWF), tissue factor (TF), tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1) and tissue factor pathway inhibitor (TFPI) levels were measured at baseline and after LT₄ suppression therapy.
Results  Plasma levels of fibrinogen, d-dimer, vWF, TF and PAI-1 increased significantly after treatment with LT₄ for 1 year. Serum FT₄ was a significant predictor of increased fibrinogen, vWF and PAI-1 levels, when the data was controlled for age and BMI.
Conclusions  Our results suggest that LT₄ suppression therapy for benign thyroid nodules is associated with enhanced coagulation.