Ethanol inhibits dopamine uptake via organic cation transporter 3: Implications for ethanol and cocaine co-abuse.

Concurrent cocaine and alcohol use is among the most frequent drug combination, and among the most dangerous in terms of deleterious outcomes. Cocaine increases extracellular monoamines by blocking dopamine (DA), norepinephrine (NE) and serotonin (5-HT) transporters (DAT, NET and SERT, respectively). Likewise, ethanol also increases extracellular monoamines, however evidence suggests that ethanol does so independently of DAT, NET and SERT. Organic cation transporter 3 (OCT3) is an emergent key player in the regulation of monoamine signaling. Using a battery of in vitro, in vivo electrochemical, and behavioral approaches, as well as wild-type and constitutive OCT3 knockout mice, we show that ethanol's actions to inhibit monoamine uptake are dependent on OCT3. These findings provide a novel mechanistic basis whereby ethanol enhances the neurochemical and behavioral effects of cocaine and encourage further research into OCT3 as a target for therapeutic intervention in the treatment of ethanol and ethanol/cocaine use disorders.

Sexual dimorphisms in serum calcium and phosphate concentrations in the Rotterdam Study.

Sex differences in serum phosphate and calcium have been reported but the exact nature and underlying regulatory mechanisms remain unclear. We aimed to compare calcium and phosphate concentrations between sexes, and explore potential covariates to elucidate underlying mechanisms of sex differences in a prospective, population-based cohort study. Pooled data of subjects > 45 years from three independent cohorts of the Rotterdam Study (RS) were used: RS-I-3 (n = 3623), RS-II-1 (n = 2394), RS-III-1 (n = 3241), with separate analyses from an additional time point of the first cohort RS-I-1 (n = 2688). Compared to men, women had significantly higher total serum calcium and phosphate concentrations which was not explained by BMI, kidney function nor smoking. Adjustment for serum estradiol diminished sex differences in serum calcium while adjustment for serum testosterone diminished sex differences in serum phosphate. Adjustment for vitamin D and alkaline phosphatase did not change the association between sex and calcium or phosphate in RS-I-1. In the sex-combined group, both serum calcium and phosphate decreased with age with a significant interaction for sex differences for serum calcium but not phosphate. In sex-stratified analyses, serum estradiol but not testosterone was inversely associated with serum calcium in both sexes. Serum estradiol was inversely associated with serum phosphate in both sexes to a similar degree, while serum testosterone was inversely associated with serum phosphate in both sexes with an apparent stronger effect in men than in women. Premenopausal women had lower serum phosphate compared to postmenopausal women. Serum testosterone was inversely associated with serum phosphate in postmenopausal women only. In conclusion, women > 45 years have higher serum calcium and phosphate concentrations compared to men of similar age, not explained by vitamin D or alkaline phosphatase concentrations. Serum estradiol but not testosterone was inversely associated with serum calcium while serum testosterone was inversely associated with serum phosphate in both sexes. Serum testosterone may in part explain sex differences in serum phosphate while estradiol could partly explain sex differences in serum calcium.

Age-dependent sex differences in calcium and phosphate homeostasis.

BACKGROUND: Sex differences in calcium and phosphate have been observed. We aimed to assess a relation with age. METHODS: We used the laboratory values of serum calcium, phosphate and albumin from three different samples ( 2005, 2010 and 2014 years) using the hospital information system of Erasmus MC, Rotterdam. The samples were divided into three age groups: 1-17, 18-44 and ≥45 years. Sex differences in calcium and phosphate were analyzed using ANCOVA, adjusting for age and serum albumin. Furthermore, sex by age interactions were determined and we analyzed differences between age groups stratified by sex. RESULTS: In all three samples there was a significant sex × age interaction for serum calcium and phosphate, whose levels were significantly higher in women compared to men above 45 years. No sex differences in the younger age groups were found. In men, serum calcium and phosphate levels were highest in the youngest age group compared to age groups of 18-44 and ≥45 years. In women, serum calcium levels were significantly higher in the age group 1-17 and the age group ≥45 years compared to the 18-44 years age group. In women, serum phosphate was different between the three different age groups with highest level in the group 1-17 years and lowest in the group 18-44 years. CONCLUSION: There are age- dependent sex differences in serum calcium and phosphate. Furthermore, we found differences in serum calcium and phosphate between different age groups. Underlying mechanisms for these age- and sex- differences are not yet fully elucidated.

NLX-112, a highly selective 5-HT1A receptor agonist: Effects on body temperature and plasma corticosterone levels in rats.

NLX-112 (a.k.a. F13640 or befiradol), exhibits nanomolar affinity, exceptional selectivity and high agonist efficacy at 5-hydroxytryptamine 5-HT1A receptors. It possesses marked activity in a variety of animal models of depression, pain and L-DOPA-induced dyskinesia. However, its influence on translational biomarkers of central 5-HT1A receptor activation has not been previously described. Here, we report on the activity, in rats, of NLX-112 to increase plasma corticosterone levels and produce hypothermia, two responses which are also elicited by 5-HT1A receptor agonists in humans. NLX-112 elicited dose-dependent hypothermia (minimal effective dose, MED: 0.31mg/kg p.o.) and also increased plasma corticosterone both by oral and intraperitoneal routes (MED: 0.63mg/kg in both cases). The increase in corticosterone induced by NLX-112 (0.63mg/kg p.o.) was abolished by co-administration of the selective 5-HT1A receptor antagonist, WAY100635. Additionally, NLX-112 also dose-dependently induced flat body posture, forepaw treading and lower lip retraction (MEDs 0.31-0.63mg/kg p.o.). The doses of NLX-112 which induce hypothermia or corticosterone release were similar to those inducing serotonergic behaviors but greater than those reported previously in models of therapeutic-like activity (range 0.04 to 0.16mg/kg). Overall, the present study provides information for clinical dose estimations of NLX-112 and suggests that therapeutic effects may occur at doses below those at which biomarker responses are observed.

Serum Phosphate Is Associated With Fracture Risk: The Rotterdam Study and MrOS.

Extreme phosphate levels (P) have been associated with mineralization defects and increased fracture risk. Whether P within normal range is related to bone health in the general population is not well understood. To investigate the association of P with bone mineral density (BMD) and fracture risk, we assessed two population-based cohorts: the Dutch Rotterdam Study (RS-I, RS-II, RS-III; n = 6791) and the US Osteoporotic Fractures in Men (MrOS; n = 5425) study. The relationship of P with lumbar spine (LS) and femoral neck (FN) BMD was tested in all cohorts via linear models; fracture risk was tested in RS-I, RS-II, and MrOS through Cox models, after follow-up of 8.6, 6.6, and 10.9 years, respectively. Adjustments were made for age, body mass index, smoking, serum levels of calcium, potassium, 25-hydroxyvitamin D, estimated glomerular filtration rate (eGFR), FN-BMD, prevalent diabetes, and cardiovascular disease. Additional adjustments were made for phosphate intake, parathyroid hormone, and fibroblast growth factor 23 levels in MrOS. We further stratified by eGFR. Results were pooled through study-level meta-analyses. Hazard ratios (HR) and betas (ß) (from meta-analyses) are expressed per 1 mg/dL P increase. P was positively associated with fracture risk in men and women from RS, and findings were replicated in MrOS (pooled HR all [95% CI]: 1.47 [1.31-1.65]). P was associated with fracture risk in subjects without chronic kidney disease (CKD): all (1.44 [1.26-1.63]) and in men with CKD (1.93 [1.42-2.62]). P was inversely related to LS-BMD in men (ß: -0.06 [-0.11 to -0.02]) and not to FN-BMD in either sex. In summary, serum P was positively related to fracture risk independently from BMD and phosphate intake after adjustments for potential confounders. P and LS-BMD were negatively related in men. Our findings suggest that increased P levels even within normal range might be deleterious for bone health in the normal population. © 2017 American Society for Bone and Mineral Research.

Osteoclastogenic capacity of peripheral blood mononuclear cells is not different between women with and without osteoporosis.

INTRODUCTION: Peripheral Blood Mononuclear Cells (PBMCs) have been extensively used as a culture model to generate osteoclasts in vitro. The aim of this study was to assess the osteoclastogenic potential of PBMCs derived from post-menopausal women with longstanding osteoporosis and compare this with PBMCs from healthy controls. MATERIAL AND METHODS: We selected from the population-based Rotterdam Study 82 participants of which 43 were diagnosed with osteoporosis (T-score below -2.5 at the lumbar spine) and the presence of at least 1 fracture and 29 healthy controls (T-score above 1; no fracture). PBMCs were differentiated into osteoclasts, and both differentiation capacity and activity were measured. Total RNA was obtained to assess gene expression of osteoclast markers. Deoxypyridinoline (DPD) was measured in plasma as a marker for bone resorption, in vivo. RESULTS: Neither the number of osteoclasts nor cathepsin K (CTSK) and dendritic cell-specific transmembrane protein (TM7SF4) gene expression was significantly different between both groups. There was also no significant difference in resorption pit area and plasma DPD levels. Stratification by fracture type into a group with vertebral, non-vertebral and both vertebral and non-vertebral fractures showed no difference in osteoclast formation or osteoclastic bone resorption. However, plasma DPD, but not the RNA expression markers, was significantly lower in the group of subjects with vertebral fracture group and those with vertebral and non-vertebral fractures compared to the healthy controls. No differences in osteoclastogenesis, osteoclastic resorption and plasma DPD levels were detected also after exclusion of past or present users of bisphosphonates and glucocorticoids. Stratification into high and low DPD levels showed higher osteoclastogenesis and more osteoclastic bone resorption in the high DPD group compared to the low DPD levels within the group of osteoporotic subjects. CONCLUSION: This study showed no difference in PBMC osteoclastogenic capacity and activity between women with and without osteoporosis and at least one previous fracture, who were on average 29.5years after menopause, suggesting that there is no difference in circulating osteoclast precursors. Although we cannot exclude that circulating precursors may behave differently at the bone site, it is possible that long after menopause a more stable phase of bone turnover is reached compared to earlier after the start of menopause in which differences in circulating osteoclast precursors and osteoclastogenic potential are more prominent.

Novel Compound Heterozygous Mutations in the CYP27B1 Gene Lead to Pseudovitamin D-Deficient Rickets.

Pseudovitamin D deficiency is the consequence of a genetic defect in the CYP27B1 gene resulting in diminished or absent conversion of 25-hydroxyvitamin D3 (25-(OH)D3) into 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and leads to growth retardation and rickets, usually in the first 2 years of life. DNA obtained from human leucocytes from a patient suspected of pseudovitamin D deficiency and her healthy parents was sequenced for a genetic defect in the CYP27B1 gene. In silico analyses on the mutations were performed using online available software. The 1α-hydroxylase activity of the patient, her parents, and a sample derived from a mixed buffy coat of healthy blood donors was measured by culturing peripheral blood mononuclear cells with 25-(OH)D3 and measuring 1,25-(OH)2D3 production. DNA sequencing of the patient suspected of pseudovitamin D deficiency revealed compound heterozygosity in the CYP27B1 gene for a (c413G>T) mutation in exon 3 (R138L) and a (c1232G>A) mutation in exon 8 (C411Y). In silico analyses confirmed that mutations at these positions are probably damaging for the protein since the amino acids are situated in a highly conserved region. In vitro analyses showed a nearly absent 1α-hydroxylase activity in the patient compared to the healthy blood donors. Her healthy parents each of whom carried one of the mutations also had compromised conversion of 25-(OH)D3 into 1,25-(OH)2D3 in peripheral blood mononuclear cells, being only marginally higher than in the patient. We discovered novel compound heterozygous mutations in the CYP27B1 gene in a young girl presenting with pseudovitamin D-deficient rickets, leading to severely decreased 1,25-(OH)2D3 production. Furthermore, both heterozygous parents showed a diminished 1α-hydroxylase activity.

Lifelong challenge of calcium homeostasis in male mice lacking TRPV5 leads to changes in bone and calcium metabolism.

Trpv5 plays an important role in calcium (Ca2+) homeostasis, among others by mediating renal calcium reabsorption. Accordingly, Trpv5 deficiency strongly stresses Ca2+ homeostasis in order to maintain stable serum Ca2+. We addressed the impact of lifelong challenge of calcium homeostasis on the bone phenotype of these mice.Aging significantly increased serum 1,25(OH)2D3 and PTH levels in both genotypes but they were more elevated in Trpv5-/- mice, whereas serum Ca2+ was not affected by age or genotype. Age-related changes in trabecular and cortical bone mass were accelerated in Trpv5-/- mice, including reduced trabecular and cortical bone thickness as well as reduced bone mineralization. No effect of Trpv5 deficiency on bone strength was observed. In 78-week-old mice no differences were observed between the genotypes regarding urinary deoxypyridinoline, osteoclast number, differentiation and activity as well as osteoclast precursor numbers, as assessed by flow cytometry.In conclusion, life-long challenge of Ca2+ homeostasis present in Trpv5-/- mice causes accelerated bone aging and a low cortical and trabecular bone mass phenotype. The phenotype of the Trpv5-/- mice suggests that maintenance of adequate circulatory Ca2+ levels in patients with disturbances in Ca2+ homeostasis should be a priority in order to prevent bone loss at older age.

Cross-tolerance to cannabinoids in morphine-tolerant rhesus monkeys.

RATIONALE: Opioids remain the drugs of choice for treating moderate to severe pain, although adverse effects limit their use. Therapeutic utility might be improved by combining opioids with other drugs to enhance analgesic effects, but only if adverse effects are not similarly changed. OBJECTIVE: Cannabinoids have been shown to enhance the antinociceptive potency of opioids without increasing other effects; this study examined whether the effectiveness of cannabinoids is altered in morphine-dependent monkeys. METHODS: Four monkeys received up to 10 mg/kg morphine twice daily. Changes in the antinociceptive effects of opioid receptor agonists (morphine, U50,488) and cannabinoid receptor agonists (WIN 55,212, CP 55,940, and Δ(9)-tetrahydrocannabinol [THC]) were determined by measuring the latency for monkeys to remove their tails from 40, 50, 54, and 58 °C water. RESULTS: Before treatment, all drugs increased tail withdrawal latency from warm (54 °C) water. Chronic morphine treatment decreased the potency of each drug; the magnitude of rightward shift in dose-effect curves was greatest for morphine, WIN 55,212 and CP 55,940 with at least sixfold shifts for each drug during treatment. Discontinuation of morphine treatment resulted in signs that are indicative of withdrawal, including increased heart rate, decreased daytime activity, and tongue movement. CONCLUSION: Tolerance developed to the antinociceptive effects of morphine and cross-tolerance developed to cannabinoids under conditions that produced modest physical dependence. Compared with the doses examined in this study, much smaller doses of opioids have antinociceptive effects when given with cannabinoids; it is possible that tolerance will not develop to chronic treatment with opioid/cannabinoid mixtures.

NLX-112, a novel 5-HT1A receptor agonist for the treatment of L-DOPA-induced dyskinesia: Behavioral and neurochemical profile in rat.

L-DOPA is the gold-standard treatment for Parkinson's disease (PD), but induces troublesome dyskinesia after prolonged treatment. This is associated with the 'false neurotransmitter' conversion of L-DOPA to dopamine by serotonin neurons projecting from the raphe to the dorsal striatum. Reducing their activity by targeting pre-synaptic 5-HT1A receptors should thus be an attractive therapeutic strategy, but previous 5-HT1A agonists have yielded disappointing results. Here, we describe the activity of a novel, highly selective and potent 5-HT1A agonist, NLX-112 (also known as befiradol or F13640) in rat models relevant to PD and its associated affective disorders. NLX-112 (0.16 mg/kg, i.p.) potently and completely reversed haloperidol-induced catalepsy in intact rats and abolished L-DOPA-induced Abnormal Involuntary Movements (AIMs) in hemiparkinsonian rats, an effect that was reversed by the selective 5-HT1A antagonist, WAY100635. In microdialysis experiments, NLX-112 profoundly decreased striatal 5-HT extracellular levels, indicative of inhibition of serotonergic function. NLX-112 also blunted the L-DOPA-induced surge in dopamine levels on the lesioned side of the brain, an action that likely underlies its anti-dyskinetic effects. NLX-112 (0.16 mg/kg, i.p.) robustly induced rotations in hemiparkinsonian rats, suggesting that it has a motor facilitatory effect. Rotations were abolished by WAY100635 and were ipsilateral to the lesioned side, suggesting a predominant stimulation of the dopamine system on the non-lesioned side of the brain. NLX-112 also efficaciously reduced immobility time in the forced swim test (75% reduction at 0.16 mg/kg, i.p.) and eliminated stress-induced ultrasonic vocalization at 0.08 mg/kg, i.p., effects consistent with potential antidepressant- and anxiolytic-like properties. In other tests, NLX-112 (0.01-0.16 mg/kg, i.p.) did not impair the ability of L-DOPA to rescue forepaw akinesia in the cylinder test but decreased rotarod performance, probably due to induction of flat body posture and forepaw treading which are typical of 5-HT1A agonists upon acute administration. However, upon repeated administration of NLX-112 (0.63 mg/kg, i.p., twice a day), flat body posture and forepaw treading subsided within 4 days of treatment. Taken together, these observations suggest that NLX-112 could exhibit a novel therapeutic profile, combining robust anti-dyskinetic properties without impairing the therapeutic properties of L-DOPA, and with additional beneficial effects on non-motor (affective) symptoms.

Physiological and behavioral effects of amphetamine in BACE1(-/-) mice.

ß-Site APP-cleaving Enzyme 1 (BACE1) is a protease that has been linked to schizophrenia, a severe mental illness that is potentially characterized by enhanced dopamine (DA) release in the striatum. Here, we used acute amphetamine administration to stimulate neuronal activity and investigated the neurophysiological and locomotor-activity response in BACE1-deficient (BACE1(-/-) ) mice. We measured locomotor activity at baseline and after treatment with amphetamine (3.2 and 10 mg/kg). While baseline locomotor activity did not vary between groups, BACE1(-/-) mice exhibited reduced sensitivity to the locomotor-enhancing effects of amphetamine. Using high-performance liquid chromatography (HPLC) to measure DA and DA metabolites in the striatum, we found no significant differences in BACE1(-/-) compared with wild-type mice. To determine if DA neuron excitability is altered in BACE1(-/-) mice, we performed patch-clamp electrophysiology in putative DA neurons from brain slices that contained the substantia nigra. Pacemaker firing rate was slightly increased in slices from BACE1(-/-) mice. We next measured G protein-coupled potassium currents produced by activation of D2 autoreceptors, which strongly inhibit firing of these neurons. The maximal amplitude and decay times of D2 autoreceptor currents were not altered in BACE1(-/-) mice, indicating no change in D2 autoreceptor-sensitivity and DA transporter-mediated reuptake. However, amphetamine (30 µm)-induced potassium currents produced by efflux of DA were enhanced in BACE1(-/-) mice, perhaps indicating increased vesicular DA content in the midbrain. This suggests a plausible mechanism to explain the decreased sensitivity to amphetamine-induced locomotion, and provides evidence that decreased availability of BACE1 can produce persistent adaptations in the dopaminergic system.

The T-13910C polymorphism in the lactase phlorizin hydrolase gene is associated with differences in serum calcium levels and calcium intake.

The C-variant of a T-13910C polymorphism (rs4988235; NT_022135.15:g.25316568G > A) upstream of the lactase phlorizin hydrolase (LPH) gene causes lactose intolerance. Association studies with differences in bone parameters and fracture risk have been inconclusive. The objective of this study was to examine the association of LPH rs4988235 with body height and bone parameters and calcium homeostasis in two elderly populations of Dutch Caucasians and assess interaction with vitamin D receptor (VDR) polymorphisms. Genotyping of LPH and VDR polymorphisms was performed in 6367 individuals from the Rotterdam Study and 844 from the Longitudinal Aging Study Amsterdam (LASA). Associations with age, height, weight, bone mineral density (BMD), skeletal morphometric parameters and serum vitamin D and calcium levels, and dietary calcium intake were assessed using ANOVA or analysis of covariance, and allele dose effect was assessed using linear regression analysis. Fracture risk was analyzed using Cox's proportional hazard regression analysis. Associations with body height (p = 2.7 × 10(-8)) and vertebral area (p = .048) found in the Rotterdam Study were explained by population stratification, as assessed by principal-component analyses, and disappeared after additional adjustments. No associations with femoral neck or lumbar spine BMD or with fracture risk were detected. Calcium intake and serum ionized serum calcium were significantly lower in C-homozygotes (p = 9.2 × 10(-7), p = .02, respectively). For none of the parameters studied was interaction between the T-13910C polymorphism and VDR block 5 haplotype 1 observed. We show that the C allele of the T-13910C polymorphism causing lactose intolerance is associated with lower dietary calcium intake and serum calcium levels but not with BMD or fractures. The associations observed with height and vertebral area were the result of population stratification. This demonstrates the impact of population stratification and urges researchers to carefully take this into account in genetic associations, in particular, in dietary intake-related phenotypes, of which LPH and lactose intolerance are a strong example.

A method towards simulating the total luminous flux of a monochromatic high power LED operated in a pulsed manner.

High power light-emitting diodes (HPLEDs) are frequently being operated in a pulsed manner. The research presented here focuses on the optical, electrical and thermal behaviour of a HPLED under pulse width modulation (PWM), and has the following twofold aim. Firstly, investigating the temperature dependence of the HPLED's efficiency, where it was found that the exact method of operation and the definition of calculation is crucial when making claims. Secondly, we propose a method to simulate the absolute emitted luminous flux of a current driven HPLED under PWM. This is done by making use of experimentally determined characteristic parameters of the HPLED. This has as advantage that no further physical measurements are needed to investigate the HPLEDs behavior under numerous different PWM circumstances.

Antagonist-precipitated and discontinuation-induced withdrawal in morphine-dependent rhesus monkeys.

RATIONALE: Upon discontinuation of chronic opioid treatment, withdrawal typically peaks in 1-3 days and decreases markedly within 1 week; however, persistent physiological changes have been reported long after other signs have waned. OBJECTIVE: The goal of this study was to compare the discriminative stimulus, directly observable signs, and physiological effects of withdrawal in morphine-treated monkeys. MATERIALS AND METHODS: Monkeys received 5.6 mg/kg/12 h morphine and discriminated 0.0178 mg/kg naltrexone while responding under a fixed-ratio 5 schedule of stimulus-shock termination. Drug discrimination, behavioral observation, and telemetry were used to monitor the emergence of withdrawal, as well as any persistent changes, following discontinuation of morphine treatment. RESULTS: Naltrexone dose (0.001-0.032 mg/kg, s.c.) was positively related with indices of withdrawal. In the discrimination study, monkeys responded on the naltrexone lever 1-5 days following discontinuation of treatment; thereafter, they responded exclusively on the saline lever. After discontinuation of morphine, the frequency of observable signs peaked within 2-3 days and most were not significantly increased after 5 days. In contrast, increased heart rate and body temperature persisted for 14 days, returning to values obtained prior to discontinuation by 21 days. CONCLUSIONS: To the extent that discriminative stimulus effects of withdrawal in nonhumans are predictive of subjective reports of withdrawal in humans, these data indicate that effective treatments for opioid dependence must address not only the short-term subjective components of withdrawal but also, and perhaps more importantly, lingering behavioral and physiological effects that might contribute to relapse long after chronic drug use is discontinued.

Estrogen receptor alpha gene polymorphisms are associated with estradiol levels in postmenopausal women.

OBJECTIVE: Postmenopausal estradiol (E(2)) levels vary widely between individuals and this variation is an important determinant of diseases such as osteoporosis. It has been suggested that the estrogen receptor alpha (ESR1) gene may influence peripheral E(2) levels, but the role of common sequence variations in the ESR1 gene is unclear. METHODS: In 631 postmenopausal women and 528 men from the Rotterdam Study, a population-based, prospective cohort study of individuals aged 55 years and over, ESR1 PvuII-XbaI haplotypes were determined and correlated with plasma E2 levels. RESULTS: In women, haplotype 1 (T-A) was significantly associated with an allele-dose-dependent decrease in E(2). After adjusting for age, body mass index, years since menopause and testosterone levels, plasma E(2) levels decreased by 1.90 pmol/l per allele copy of this haplotype (P < 0.05). Extreme genotypes, representing 23 and 27% of the population, varied by 3.93 pmol/l. No association with plasma testosterone was observed. In a subset of 446 women, no association of genotype with plasma concentrations of dehydroepiandrosterone sulfate, androstenedione or estrone was seen. In men, none of the sex hormone levels was associated with the ESR1 PvuII-XbaI haplotypes. CONCLUSION: We have demonstrated a role for genetic variations in the ESR1 gene in determining post-menopausal E(2) levels in women.

Differential in vivo inhibition of [3H]nemonapride binding by atypical antipsychotics in rat striatum, olfactory lobes, and frontal cortex.

Dopamine D2 receptor blockade is thought to be mandatory for antipsychotic action because most of the currently used antipsychotics have high affinity at these receptors. Here, we examined the in vivo binding characteristics of the D2-like receptor antagonist [3H]nemonapride in rat brain areas including the striatum, olfactory lobes and frontal cortex and its inhibition by a series of D2 antagonist antipsychotics. In vivo affinity of [3H]nemonapride was similar (apparent Kd value: 0.05 micromol/kg) in all brain regions examined. The estimated number of binding sites was higher in the striatum (66 fmol/mg wet weight) than in the olfactory lobes (28 fmol/mg wet weight) and the frontal cortex (21 fmol/mg wet weight). In the striatum, [3H]nemonapride binding was inhibited in a dose-dependent manner with the following order of potency (ED50, mg/kg): nemonapride (0.04), raclopride (0.13), spiperone and risperidone (0.14), haloperidol (0.21), clozapine (7.2) and thioridazine (9.4); in the olfactory lobes: nemonapride (0.03), raclopride and spiperone (0.09), haloperidol (0.10), risperidone (0.15), thioridazine and clozapine (11); in the frontal cortex, only the high affinity dopamine D2 antagonist compounds nemonapride (0.05), haloperidol (0.09), and raclopride (0.12) significantly decreased the binding of [3H]nemonapride. The present data suggest that conventional and atypical antipsychotics may be distinguished by their differential occupancy of striatal versus frontocortical D2-like receptors in vivo.

Monoaminergic drugs and directly observable signs of LAAM withdrawal in rhesus monkeys.

Monoaminergic ligands modified a naltrexone discriminative stimulus in rhesus monkeys dependent on 2 mg/kg per day of the mu opioid L-alpha-acetylmethadol (LAAM). This study examined a role for monoamines in the directly observable and physiologic manifestations of LAAM withdrawal induced by naltrexone in the same monkeys. The effects of saline, clonidine (0.032 mg/kg), haloperidol (0.032 mg/kg), cocaine (1.0 mg/kg), amphetamine (1.0 mg/kg) and imipramine (10.0 mg/kg) were examined in LAAM-dependent monkeys that subsequently received saline or naltrexone (0.0001-1.0 mg/kg). Naltrexone dose-dependently increased respiration, abdominal rigidity and salivation. Clonidine attenuated each of these withdrawal signs, whereas haloperidol increased some (i.e. respiration) and decreased others (i.e. salivation). When administered alone, cocaine and amphetamine increased respiration and also increased the respiratory stimulant effects of naltrexone; cocaine and amphetamine did not attenuate any measure of withdrawal. With the exception of a decrease in naltrexone-induced salivation, imipramine was without effect. These results are strikingly different from results in these same LAAM-dependent monkeys showing that cocaine and amphetamine, but not clonidine, markedly attenuated a naltrexone discriminative stimulus. That monoaminergic ligands differentially alter the directly observable and discriminative stimulus effects of naltrexone in LAAM-dependent monkeys supports the view that monoamines differentially mediate the physical manifestations (norepinephrine) and subjective experience (dopamine) of opioid withdrawal.

Influence of virtual images on the signal-to-noise ratio in digital in-line particle holography.

A theoretical analysis describing the dependence of the signal-tonoise ratio (SNR) on the number of pixels and the number of particles is presented for in-line digital particle holography. The validity of the theory is verified by means of numerical simulation. Based on the theory we present a practical performance benchmark for digital holographic systems. Using this benchmark we improve the performance of an experimental holographic system by a factor three. We demonstrate that the ability to quantitatively analyze the system performance allows for a more systematic way of designing, optimizing, and comparing digital holographic systems.

The Discriminative stimulus effects of gamma-hydroxybutyrate and related compounds in rats discriminating baclofen or diazepam: The role of GABA(B) and GABA(A) receptors.

The discriminative stimulus effects of gamma-hydroxybutyrate (GHB) can be mimicked by GABA(A) receptor-positive modulators (e.g., diazepam) and GABA(B) receptor agonists (e.g., baclofen). The purposes of this study were to see whether stimulus control could be established with baclofen and to further characterize the role of GABAergic mechanisms in the behavioral actions of GHB by evaluating GHB and related compounds in rats discriminating either diazepam or baclofen. Training criteria were satisfied with baclofen and diazepam after 69 and 44 sessions, respectively. GHB and its precursors gamma-butyrolactone and 1,4-butanediol occasioned >80% responding on the drug-associated lever in rats discriminating baclofen and <11% in rats discriminating diazepam. Diazepam and other GABA(A) receptor-positive modulators occasioned intermediate levels of responding on the baclofen lever, whereas baclofen occasioned less than 4% responding on the diazepam lever. The GABA(B) receptor antagonist CGP 35348 [(3-aminopropyl)(diethoxymethyl) phosphinic acid] partially antagonized the effects of baclofen as well as the baclofen-like effects of GHB, and flumazenil partially antagonized the effects of diazepam. This study established stimulus control with baclofen, and substitution data provided direct evidence for a role of GABAergic, especially GABA(B), mechanisms in the discriminative stimulus effects of GHB. The lack of substitution by GHB or its metabolic precursors for diazepam indicates a comparatively smaller role of GABA(A) mechanisms in these effects of GHB. The inability of CGP 35348 to completely attenuate the effects of baclofen and GHB suggests that multiple receptors could be involved in the discriminative stimulus effects of GHB.

Holographic simultaneous readout polarization multiplexing based on photoinduced anisotropy in bacteriorhodopsin.

Bacteriorhodopsin (bR) is a reversible photochromic protein that can be used as a holographic medium. The dichroic absorption of the bR molecule is polarization dependent, thereby allowing for the recording of polarization holograms. The properties of polarization holograms can be used to multiplex two independent images in a single bR film. A new technique and associated polarization-multiplexing scheme are demonstrated that allow for simultaneous readout of two orthogonally polarized images while achieving a high normalized diffraction efficiency for each of the individual images.