DRD2 mRNA Expression Research Articles

Sex and Age Differences in Ontogeny of Alloparenting: A Relation to Forebrain DRD1, DRD2, and HTR2A mRNA Expression?

Alloparenting refers to the practice of caring for the young by individuals other than their biological parents. The relationship between the dynamic changes in psychological functions underlying alloparenting and the development of specific neuroreceptors remains unclear. Using a classic 10-day pup sensitization procedure, together with a pup preference and pup retrieval test on the EPM (elevated plus maze), we showed that both male and female adolescent rats (24 days old) had significantly shorter latency than adult rats (65 days old) to be alloparental, and their motivation levels for pups and objects were also significantly higher. In contrast, adult rats retrieved more pups than adolescent rats even though they appeared to be more anxious on the EPM. Analysis of mRNA expression using real-time-PCR revealed a higher dopamine D2 receptor (DRD2) receptor expression in adult hippocampus, amygdala, and ventral striatum, along with higher dopamine D1 receptor (DRD1) receptor expression in ventral striatum compared to adolescent rats. Adult rats also showed significantly higher levels of 5-hydroxytryptamine receptor 2A (HTR2A) receptor expression in the medial prefrontal cortex, amygdala, ventral striatum, and hypothalamus. These results suggest that the faster onset of alloparenting in adolescent rats compared to adult rats, along with the psychological functions involved, may be mediated by varying levels of dopamine DRD1, DRD2, and HTR2A in different forebrain regions.

English

The objective of this study is to study the sedative and hypnotic effects of the compatibility of Schisandra chinensis (SC) and Polygala tenuifolia (PT) on insomnia mice and its mechanisms. The 160 SPF KM mice were divided into 8 groups with 20 each group (10 female and 10 male mice), including control, model, estazolam, SC, PT, SC-PT 1:1, SC-PT 1:2, and SC-PT 2:1 group. Insomnia mice model was established with intraperitoneal injection of P-chlorophenylalanine (PCPA) for 3 days. The mice were investigated by the sleep time of mice induced by pentobarbital sodium, the levels of GABA, DA, 5-HT and 5-HIAA in hypothalamus by enzyme-linked immunosorbent assay, and the GABAα1 and DRD2 mRNA expression in hypothalamus by quantitative real-time polymerase chain reaction (RT-qPCR). SC-PT reduced the sleep latency of insomnia mice and prolonged the Pentobarbital-sodium induced sleep time than model group. SC-PT 2:1 group increased the levels of 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), γ-Aminobutyric acid (GABA) and the expression of GABAARα1 and decreased the levels of dopamine (DA) and the expression of DRD2 in the hypothalamus of insomnia mice. The compatibility of SC and PT can enhance the function of sedation and hypnosis than single group. This study provides a basis for the compatibility of SC and PT in the insomnia treatment. Key words: Schisandra chinensis, Polygala tenuifolia, mice, sedative, hypnotic, γ-Aminobutyric acid, dopamine.

Dysregulation of striatal dopamine D2/D3 receptor-mediated by hypocretin induces depressive behaviors in rats

BackgroundThe dysregulation of the dopamine system contributes to depressive-like behaviors in rats, and the neurological functions regulated by hypocretin are severely affected in depression. However, whether suvorexant plays a role in alleviating depression by affecting the dopamine system is unclear. MethodsTo preliminarily explore the mechanism of suvorexant (10 mg/kg) in the treatment of depression, the mRNA and protein expression of TH, Drd2, Drd3, GluN2A, DAT, and GluN2B in the striatum of rats was quantified by qPCR and western blotting. The plasma hypocretin-1 and dopamine levels and the striatal dopamine levels were determined by ELISA. Resultsi) Compared to those of the control group, chronic unpredictable mild stress (CUMS) rats showed depressive-like behaviors, which were subsequently reversed by treatment with suvorexant. ii) The mRNA and protein expressions of TH, Drd2, Drd3, GluN2A, and GluN2B in the striatum of CUMS were significantly increased compared with those in the controls, but decreased after suvorexant treatment. iii) Compared with those in the control group, the plasma and striatal dopamine levels of CUMS decreased while plasma hypocretin-1 levels increased, which was reversed after suvorexant treatment. Limitationsi) The suvorexant is a dual hypocretin receptor antagonist; however, the responsible receptor is unclear. ii) We only focused on related factors in the striatum but did not explore other brain regions, nor did we directly explore the relationship among these factors. ConclusionDepressive-like behaviors induced by CUMS can be reversed by suvorexant, and the therapeutic effects of suvorexant may be mediated by affecting the dopamine system.

Effects of Long-Term Administration of Q808 on Hippocampal Transcriptome in Healthy Rats.

Epilepsy treatment with antiepileptic drugs (AEDs) is usually requires for many years. Q808 is an innovative antiepileptic chemical. It exerts effective antiepileptic effect against various epilepsy models. Exploring the gene transcriptomic profile of long-term treatment of Q808 is necessary. In the present study, hippocampus RNA-sequencing was performed to reveal the transcriptome profile of rats before and after treatment of Q808 for 28 d. Results confirmed 51 differentially expressed genes (DEGs) between Q808 and healthy control groups. Gene cluster analysis showed that most upregulated DEGs linked to response to drug and nucleus, most downregulated DEGs linked to locomotory, neuronal cell body, and drug binding. Most of DEGs were enriched in the signaling transduction, substance dependence, nervous system, and neurodegenerative disease pathways. Furthermore, quantitative real-time PCR analysis confirmed that Q808 significantly increased the expression of neuroprotective genes, such as Mdk, and decreased the mRNA levels of Penk, Drd1, and Adora2a, which are highly expressed in epilepsy models. In addition, Q808 decreased the mRNA expression of Pde10A and Drd2, which are known to be closely associated with schizophrenia. Our study may provide a theoretical basis to explore the effect of Q808 on the susceptibility to epilepsy and other neurological diseases.

Total Barley Maiya Alkaloids Prevent Increased Prolactin Levels Caused by Antipsychotic Drugs and Reduce Dopamine Receptor D2 via Epigenetic Mechanisms.

Background: The dopamine D2 receptor (DRD2) plays an important role in the increased prolactin (PRL) levels associated with the pathogenesis of antipsychotic drugs (ADs). Elevated prolactin levels can affect people’s quality of life. Maiya alkaloids has been used to treat diseases associated with high PRL levels. Maiya, is a processed product of the mature fruits of Hordeum vulgare L. (a gramineous plant) after sprouting and drying and also a common Chinese herbal drug used in the clinic, is traditionally used to treat abnormal lactation, and is currently used clinically for the treatment of abnormal PRL levels. Aims: Epigenetic mechanisms can be related to DRD2 expression. We investigated the role of DRD2 methylation in the induction of PRL expression by ADs and the mechanism underlying the effects of total barley maiya alkaloids (TBMA) on this induction. Methods: The methylation rate of DRD2 in 46 people with schizophrenia who took risperidone was detected by MassARRAY sequencing. Humans were long term users of Ris. Seventy Sprague Dawley female rats were divided into seven groups. A rat model of risperidone-induced PRL was established, and the potential protective effects of TBMA and its components [e.g., hordenine (Hor)] on these increased PRL levels were investigated. The PRL concentration was detected by Enzyme-linked immunosorbent assay. PRL, DRD2, and DNA methyltransferase (DNMT1, DNMT3α, and DNMT3β) protein and mRNA expression were detected by western blotting and real-time polymerase chain reaction (RT-PCR), respectively. The positive rate of methylation in the DRD2 promoter region of rats was detected by MassARRAY sequencing. Results: Clinical studies showed that the positive rate of DRD2 methylation associated with increased PRL levels induced by ADs was significantly higher than in the normal prolactinemia (NPRL) group. In vivo and vitro, TBMA and Hor inhibited this induction of PRL expression and increased DRD2 expression by inhibiting the expression of the DNMTs. Conclusions: TBMA and hordenine increased DRD2 expression by inhibiting DNMT-dependent DRD2 methylation.

Effects of anesthetics on expression of dopamine and acetylcholine receptors in the rat brain in vivo.

Dopamine D2 and acetylcholine M1 receptors might be related to post-operative cognitive dysfunction. The aim of the present study is to investigate whether several anesthetics which are used for general anesthesia and/or sedation, affect expression of dopamine D2 and acetylcholine M1 receptors in the rat brain. Thirty-six male rats aged 5-9weeks old were divided into six groups (n = 6 in each group); five groups for anesthetics and one for control. The five groups were anesthetized with either dexmedetomidine 0.4µg/kg/min, propofol 50mg/kg/h, midazolam 25mg/kg/h, sevoflurane 3.3%, or nitrous oxide 75% for 4h. Then, the rats were decapitated, and the cerebral cortex, hippocampus, corpus striatum, brain stem, and cerebellum were collected from all rats. Then, real-time polymerase chain reaction was performed to examine the expression of Drd2 (cord dopamine D2 receptor) and Chrm1 (cord acetylcholine M1 receptor). There were no significant differences among the groups regarding Drd2 and Chrm1 mRNA expression of each region of the brain. Postsynaptic changes of dopamine D2 and acetylcholine M1 receptors due to administration of dexmedetomidine, propofol, midazolam, sevoflurane, and nitrous oxide are unlikely to occur at the doses of each anesthetic used in the present study.

Maternal immune activation leads to atypical turning asymmetry and reduced DRD2 mRNA expression in a rat model of schizophrenia

Atypical asymmetries have been reported in individuals diagnosed with schizophrenia, linking higher symptom severity to weaker lateralization. Furthermore, both lateralization and schizophrenia are influenced by the dopaminergic system. However, whether a direct link between the etiology of schizophrenia and atypical asymmetries exists is yet to be investigated. In this study, we examined whether maternal immune activation (MIA), a developmental animal model for schizophrenia and known to alter the dopaminergic system, induces atypical lateralization in adolescent and adult offspring. As the dopaminergic system is a key player in both, we analyzed neuronal dopamine D2 receptor (DRD2) mRNA expression. MIA was induced by injecting pregnant rats with 10 mg/kg polyinosinic:polycytidylic (PolyI:C) at gestational day 15. Controls were injected with 0.9 % NaCl. Offspring were tested at adolescence or early adulthood for asymmetry of turning behavior in the open field test. The total number of left and right turns per animal was assessed using DeepLabCut. Strength and preferred side of asymmetry were analyzed by calculating lateralization quotients. Additionally, DRD2 mRNA expression in the prefrontal cortex of offspring at both ages was analyzed using real-time PCR. MIA was associated with a rightward turning behavior in adolescents. In adults, MIA was associated with an absence of turning bias, indicating reduced asymmetry after MIA. The analysis of DRD2 mRNA expression revealed significantly lower mRNA levels after MIA compared to controls in adolescent, but not adult animals. Our results reinforce the association between atypical asymmetries, reduced DRD2 mRNA expression, and schizophrenia. However, more preclinical research is needed.

Cabergoline Stimulates Human Endometrial Stromal Cell Decidualization and Reverses Effects of Interleukin-1β In Vitro

Human embryonic implantation is regulated by neuroendocrine hormones, ovarian steroids, growth factors, and cytokines. Sympathetic innervation of the uterus also may play a role. We tested the hypothesis that cabergoline (Cb), an agonist of type 2 dopamine receptors (DRD2), could influence endometrial decidualization in vitro. Immunohistochemistry confirmed the presence of catecholaminergic neurons in human uterine tissue. DRD2 mRNA and protein expression in endometrial tissue and cells were validated by quantitative RT-PCR, cDNA microarrays, RNA sequencing, and Western blotting. Isolated human endometrial stromal cells (ESC) were subjected to dose-response and time-course experiments in the absence or presence of decidualizing hormones (10 nM estradiol, 100 nM progesterone, and 0.5 mM dibutyryl cAMP). In some cases, interleukin (IL)-1β (0.1 nM) was used as an inflammatory stimulus. Well-characterized in vitro biomarkers were quantified. DRD2 were maximally expressed in vivo in the mid-secretory phase of the cycle and upregulated in ESC in response to decidualizing hormones, as were classical (eg, prolactin) and emerging (eg, VEGF and connexin 43) differentiation biomarkers. Cabergoline treatment more than doubled decidual biomarker expression, whereas risperidone, a dopamine receptor antagonist, inhibited ESC differentiation by >50%. Cabergoline induced characteristic decidual morphology changes and blocked detrimental effects of IL-1β on decidual cytology. Our results support the hypothesis that dopaminergic neurons modulate decidualization in situ. We postulate that dopamine agonists, like Cb, could be developed as therapeutic agents to enhance implantation in couples with inflammation-associated infertility.

Menthol, a bioactive constituent of Mentha, attenuates motion sickness in mice model: Involvement of dopaminergic system.

Motion sickness (MS) occurs due to contradicting vestibular and visual inputs to the brain causing nausea and vomiting. Antidopaminergic drugs being effective in reducing MS create a path for effective therapy against MS by regulating dopamine levels. We aimed to evaluate the role of the striatum and brainstem dopamine and dopamine D2 receptor (DRD2) in MS and the efficacy of menthol (MNT) to modulate dopamine and DRD2 in vitro and in vivo for possible amelioration of MS. Evaluation of efficacy of MNT to inhibit dopamine release from PC12 cells and anti-MS efficacy in BALB/c mice model was performed. Dopamine, DRD2 expression in PC12 cells, mice striatum, and brainstem were detected using HPLC-ECD, RT-PCR, and Western blot analysis, respectively. DRD2 expression increased in calcium ionophore-treated PC12 cells compared with control cells. Pretreatment with 50μg/ml menthol decreased dopamine and DRD2 expression. Similarly, dopamine and DRD2 levels in mice striatum and brainstem of MS group (rotation induced) increased significantly compared with control group NC (no rotation). Pretreatment with menthol at 50mg/kg concentration (rotation induced) showed decreased dopamine and DRD2 expression, thus indicating ameliorative effect on MS. Hence, we suggest that increased striatum and brainstem dopamine and DRD2 levels might lead to MS symptoms, and menthol could be used as a potent herbal alternative medicine for MS. PRACTICAL APPLICATIONS: Antidopaminergic drugs being effective in reducing motion sickness (MS) creates a path for effective therapy against MS by regulating dopamine levels. Increased striatum and brainstem dopamine and Dopamine D2 receptor (DRD2) levels might lead to the MS symptoms induced by rotation stimulation in mice model. Menthol showed a prophylactic effect on rotation-induced MS by reducing striatal and brainstem dopamine levels, DRD2 mRNA, and protein expression. Menthol could be used as an herbal alternative to antidopaminergics to minimize the associated adverse effects.

Investigation of DRD2 and HTR2A mRNA Expression in Two Therapeutic States of Antipsychotic Polypharmacy and Aripiprazole Monotherapy in the Peripheral Blood of Patients With Schizophrenia

Objectives: Schizophrenia is a severe psychiatric disorder that has profound effects on both individuals and the community. Notwithstanding the suggestion for treating schizophrenia with a minimum dose of drugs, antipsychotic polypharmacy increases the patient’s care costs and drug interactions. Aripiprazole reduces the metabolic side effects of antipsychotic polypharmacy treatment. DRD2 and HTR2A can serve as predictors for response to treatment in schizophrenic patients. The purpose of this survey was to measure the DRD2 and HTR2A genes expression in the peripheral blood samples using Real-Time Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). Methods: A total of 19 patients with a long history of schizophrenia who received at least two types of antipsychotics with daily doses of more than 500 mg of chlorpromazine were entered into the study. The response rates to the treatment based on scores in the Brief Psychiatric Rating Scale (BPRS) questionnaire and DRD2 and HTR2A expression were compared between antipsychotic polypharmacy status and 6 months after monotherapy with aripiprazole. Results: The levels of DRD2 expression decreased significantly after the intervention. The mean changes in HTR2A expression and the BPRS questionnaire and also the relationship between changes in DRD2 and HTR2A expression and changes in BPRS score after the intervention were not significant. Discussion: The conversion of the antipsychotic polypharmacy state to monotherapy with aripiprazole has been accompanied by a significant decrease in DRD2A expression. These genes can be used for evaluating the response rate of schizophrenia treatments in the future.

Association of dopamine D2/3 receptor binding potential measured using PET and [11C]-(+)-PHNO with post-mortem DRD2/3 gene expression in the human brain

Open access post-mortem transcriptome atlases such as the Allen Human Brain Atlas (AHBA) can inform us about mRNA expression of numerous proteins of interest across the whole brain, while in vivo protein binding in the human brain can be quantified by means of neuroreceptor positron emission tomography (PET). By combining both modalities, the association between regional gene expression and receptor distribution in the living brain can be approximated. Here, we compare the characteristics of D2 and D3 dopamine receptor distribution by applying the dopamine D2/3 receptor agonist radioligand [11C]-(+)-PHNO and human gene expression data. Since [11C]-(+)-PHNO has a higher affinity for D3 compared to D2 receptors, we hypothesized that there is a stronger relationship between D2/3 non-displaceable binding potentials (BPND) and D3 mRNA expression. To investigate the relationship between D2/3 BPND and mRNA expression of DRD2 and DRD3 we performed [11C]-(+)-PHNO PET scans in 27 healthy subjects (12 females) and extracted gene expression data from the AHBA. We also calculated D2/D3 mRNA expression ratios to imitate the mixed D2/3 signal of [11C]-(+)-PHNO. In accordance with our a priori hypothesis, a strong correlation between [11C]-(+)-PHNO and DRD3 expression was found. However, there was no significant correlation with DRD2 expression. Calculated D2/D3 mRNA expression ratios also showed a positive correlation with [11C]-(+)-PHNO binding, reflecting the mixed D2/3 signal of the radioligand. Our study supports the usefulness of combining gene expression data from open access brain atlases with in vivo imaging data in order to gain more detailed knowledge on neurotransmitter signaling.

Administration of a putative pro-dopamine regulator, a neuronutrient, mitigates alcohol intake in alcohol-preferring rats

BackgroundExcessive alcohol intake is a serious but preventable public health problem in the United States and worldwide. Alcohol and other substance use disorders occur co-morbid with more generalized reward deficiency disorders, characterized by a reduction in dopamine (DA) signaling within the reward pathway, and classically associated with increased impulsivity, risk taking and subsequent drug seeking behavior. It is postulated that increasing dopamine availability and thus restoring DA homeostasis in the mesocorticolimbic system could reduce the motivation to seek and consume ethanol. Here, we treated animals with a neuro-nutrient, KB220Z also known as Synaptamine, designed to augment DA signaling. MethodKB220Z was administered to genetically alcohol-preferring (P) adult male and female rats by oral gavage (PO), intraperioneally (IP), or subcutaneously (SQ) for 4 consecutive days at a 3.4 mL/Kg rat equivalent dose and compared to saline (SQ, IP) or water (PO) controls. Subsequent to treatment, lever pressing and consumption of 10 % ethanol or control 3% sucrose during operant responding was assessed using a drinking in the dark multiple scheduled access (DIDMSA) binge drinking protocol. Locomotor and elevated zero maze activity, and DRD2 mRNA expression via in situ hybridization (ISH) were assessed independently following 4 days of a SQ regimen of KB220Z. ResultsKB220Z administered via IP and SQ markedly and immediately reduced binge drinking of 10 % ethanol in both male and female rats whereas PO administration took at least 3 days to decrease lever pressing for ethanol in both male and female rats. There was no effect of SQ KB220Z on 3% sucrose drinking. Elevated activity in the open field was significantly decreased, and time spent in the open arm of the EZM was moderately reduced. The regimen of SQ KB220Z did not impact the number of DRD2 punctae in neurons of the NAc, but the NAc shell expressed more DRD2 mRNA/cell than NAc core independent of KB220Z. ConclusionKB220Z attenuates ethanol drinking and other RDS behaviors in P rats possibly by acting on the dopaminergic system, but not by effecting an increase in NAc DRD2 mRNA expression.

Early weaning leads to disruption of homeostatic and hedonic eating behaviors and modulates serotonin (5HT) and dopamine (DA) systems in male adult rats

Early weaning is associated with disruption of eating behavior. However, little is known about the mechanisms behind it. 5HT and DA systems are key regulators of homeostatic and hedonic eating behaviors, respectively. Thus, this study aims to evaluate the effects of early weaning on feeding behavior and 5HT and DA systems. For this, rats were submitted to regular (PND30) or early weaning (PND15) and between PND250 and PND300 were evaluated food intake of standard diet in response to 4 h food deprivation, during the 24 h period and per phase of the circadian cycle, in addition to the palatable food intake. Additionally, body mass and mRNA expression of 5HT1B, 5HT2C, SERT, DRD1 and DRD2 were evaluated in the hypothalamus and brainstem. The results demonstrate that early weaning promoted an increase in standard food intake in response to a 4 h food deprivation in the 24 h period and in the dark phase of the circadian cycle, in addition to an increased palatable food intake. No differences in body mass between regular or early weaning were observed. In the hypothalamus, increased mRNA expression of SERT and DRD1 was observed, but decreased 5HT1B mRNA expression. In the brainstem, the expression of 5HT1B, SERT, 5HT2C, DRD1 and DRD2 was increased in early weaned rats. In a nutshell, the stress promoted by early weaning has programmed the animals to be hyperphagic and to increase their palatable food intake, which was associated with modulation of 5HT and DA systems.

Behavioral Changes and Neuronal Damage in Rhesus Monkeys after 10 Weeks of Ketamine Administration Involve Prefrontal Cortex Dopamine D2 Receptor and Dopamine Transporter

The dopamine D2 receptor (DRD2) and dopamine transporter (DAT) play a regulatory role in dopaminergic neurotransmission and thus play an important role in drug addiction. The prefrontal cortex (PFC), a critical part of the mesencephalic dopaminergic system, is thought to be involved in the development and maintenance of drug addiction. The addiction to ketamine is thought to induce behavioral effects primarily through actions on the central nervous system. However, the neural mechanism underlying the effects of ketamine addiction remains unclear. In this study, we investigate the involvement of PFC DRD2 and DAT in ketamine addiction effects after ketamine administration for 10 weeks in nonhuman primates. To this end, after administering ketamine to rhesus monkeys for 10 weeks, we assessed changes in body weight and behavior. Additionally, neuronal changes in the PFC were examined by hematoxylin and eosin (HE) staining; the DRD2 and DAT mRNA and protein expression levels in the PFC were determined by real-time PCR and Western blot analysis, respectively. After 10-week ketamine administration, the assessment of the manifestations of toxicity in rhesus monkeys revealed significant changes in body weight and behavior, decreased DRD2 and DAT mRNA and protein expression in the PFC, and histological abnormalities including neuronal eosinophilia, pyknosis and disorderly arrangement of neurons in the PFC. These results suggest that the reduced expression of DRD2 and DAT in PFC could be involved in the behavioral and the neurological changes induced by ketamine administration, which may play an important role in the molecular mechanisms of ketamine addiction.

Significant association of DRD2 enhancer variant rs12364283 with heroin addiction in a Pakistani population.

The dopamine D2 receptor encoded by DRD2 has been implicated in multiple psychiatric disorders, mediated at least in part by two intronic variants affecting mRNA splicing, rs1076560 and rs2283265, and a less frequent enhancer variant, rs12364283, which increases DRD2 mRNA expression. This study tests whether these functionally validated variants confer susceptibility toward heroin addiction in a Pakistani population. A total of 540 heroin addicts and 467 healthy controls were genotyped, basic allele and genotype tests were performed. Neither rs1076560 nor rs2283265 significantly associated with heroin addiction. The enhancer rs12364283 occurs more frequently in heroin-dependent cases than controls (MAF 13% vs. 7%, respectively), revealing significant association with heroin addiction (p=3.0E-06, OR 2.1). This study identifies rs12364283 of DRD2 as a potential risk factor for heroin addiction in the Pakistani study population. This enhancer variant had been shown to increase DRD2 mRNA expression, a possible factor in increased vulnerability to heroin addiction. Further studies are needed to validate this association of rs12364283.

A Comparison of mRNA Expression of Dopamine Receptors, Tyrosine Hydroxylase, and Dopamine Transporter in the Mesolimbic System of Rats with Different Levels of Alcohol Consumption

Despite numerous studies, there is still no clear idea on the fine mechanisms of dysfunction of the brain dopamine system during the formation of alcohol dependence. In this work, we studied the expression of genes that encode tyrosine hydroxylase (TH), a key enzyme of dopamine synthesis, dopamine transporter (DAT), dopamine receptors of the second subtype (DRD2) in the midbrain, and dopamine receptors of the first and second subtypes (DRD1 and DRD2) in the striatum of rats that consumed alcohol from the 60th to 120th days of life in the “free choice” paradigm. The most pronounced changes, a decrease in mRNA expression of DRD1 and DRD2 in the striatum, as well as DAT and TH in the midbrain, were observed in animals with a growing preference for alcohol compared to a group of rats that controlled consumption at a constantly low level. In animals with initially stable high levels of alcohol preference, a decrease in the relative expression level of DRD1 and DRD2 mRNA in the striatum was found, while there was no difference in the expression of DAT and TH mRNA in the midbrain. The expression level of DRD2 mRNA in the midbrain did not differ in all the studied groups. These data suggest that changes in the expression of mRNA of DRD1 and DRD2 in the striatum do not depend on the initial alcohol preference and are determined by the level of alcohol intoxication, while the decrease in the level of TH and DAT mRNA in the midbrain may be one of the mech-anisms of loss of control over consumption.

Increased cerebral blood flow after single dose of antipsychotics in healthy volunteers depends on dopamine D2 receptor density profiles

As a result of neuro-vascular coupling, the functional effects of antipsychotics in human brain have been investigated in both healthy and clinical populations using haemodynamic markers such as regional Cerebral Blood Flow (rCBF). However, the relationship between observed haemodynamic effects and the pharmacological action of these drugs has not been fully established. Here, we analysed Arterial Spin Labelling (ASL) rCBF data from a placebo-controlled study in healthy volunteers, who received a single dose of three different D2 receptor (D2R) antagonists and tested the association of the main effects of the drugs on rCBF against normative population maps of D2R protein density and gene-expression data. In particular, we correlated CBF changes after antipsychotic administration with non-displaceable binding potential (BPND) template maps of the high affinity D2-antagonist Positron Emission Tomography (PET) ligand [18F]Fallypride and with brain post-mortem microarray mRNA expression data for the DRD2 gene from the Allen Human Brain Atlas (ABA). For all antipsychotics, rCBF changes were directly proportional to brain D2R densities and DRD2 mRNA expression measures, although PET BPND spatial profiles explained more variance as compared with mRNA profiles (PET R2 range = 0.20–0.60, mRNA PET R2 range 0.04–0.20, pairwise-comparisons all pcorrected<0.05). In addition, the spatial coupling between ΔCBF and D2R profiles varied between the different antipsychotics tested, possibly reflecting differential affinities. Overall, these results indicate that the functional effects of antipsychotics as measured with rCBF are tightly correlated with the distribution of their target receptors in striatal and extra-striatal regions. Our results further demonstrate the link between neurotransmitter targets and haemodynamic changes reinforcing rCBF as a robust in-vivo marker of drug effects. This work is important in bridging the gap between pharmacokinetic and pharmacodynamics of novel and existing compounds.

Pituitary Pathology and Gene Expression in Acromegalic Cats.

The prevalence of GH-secreting pituitary tumors in domestic cats (Felis catus) is 10-fold greater than in humans. The predominant inhibitory receptors of GH-secreting pituitary tumors are somatostatin receptors (SSTRs) and D2 dopamine receptor (DRD2). The expression of these receptors is associated with the response to somatostatin analog and dopamine agonist treatment in human patients with acromegaly. The aim of this study was to describe pathological features of pituitaries from domestic cats with acromegaly, pituitary receptor expression, and investigate correlates with clinical data, including pituitary volume, time since diagnosis of diabetes, insulin requirement, and serum IGF1 concentration. Loss of reticulin structure was identified in 15 of 21 pituitaries, of which 10 of 15 exhibited acinar hyperplasia. SSTR1, SSTR2, SSTR5, and DRD2 mRNA were identified in the feline pituitary whereas SSTR3 and SSTR4 were not. Expression of SSTR1, SSTR2, and SSTR5 was greater in acromegalic cats compared with controls. A negative correlation was identified between DRD2 mRNA expression and pituitary volume. The loss of DRD2 expression should be investigated as a mechanism allowing the development of larger pituitary tumors.

O4.3. INCREASED CEREBRAL BLOOD FLOW AFTER SINGLE DOSE OF ANTIPSYCHOTICS IN HEALTHY SUBJECTS DEPENDS ON DOPAMINE D2 RECEPTOR DENSITY PROFILES EVALUATED WITH PET AND MRNA EXPRESSION DATA.

BackgroundPrevious studies measuring cerebral blood flow (CBF) with magnetic resonance sequences like Arterial Spin Labelling (ASL) showed that patients with schizophrenia (SCZ) have increased CBF in basal ganglia and reduced blood flow in cortical areas like the prefrontal cortex. It is still not clear whether these abnormalities are related to antipsychotic treatment or rather they reflect a disease trait independent from medication. Interestingly, administration of single dose of antipsychotics in healthy volunteers produce marked functional effects that are in the same region reported as altered in SCZ. These effects are thought to depend on dopamine D2 receptor (D2R) blockade, although their relationship with antipsychotic pharmacodynamics has not been fully established yet. In fact, the haemodynamic nature of CBF measures makes difficult to interpret drug effects in terms of altered neurotransmission function. Here, we tested whether CBF changes induced by different antipsychotics mirror receptor distribution profiles of D2R. We evaluated the correlation of CBF variation with receptor density as measured with PET and brain mRNA expression extracted from the Allen Human Brain Atlas (ABA).MethodsForty-two healthy male subjects were enrolled in a double blind, randomized, placebo-controlled, crossover study. Participants were randomized in two equal parallel groups to receive a single dose of antipsychotic/placebo in three separate sessions. In Group 1 placebo, olanzapine 7.5mg (OLA) or haloperidol 3mg (HAL) were administered before the MRI scan. In Group 2 participants received placebo, 0.5mg (lowRIS) or 2mg (highRIS) of risperidone. Regional CBF was assessed with pseudo-continuous ASL (pCASL) sequence. For each antipsychotic, a paired T-test was performed in SPM12 with global CBF values as covariate of no interest.A template image of dopamine D2 receptor density was derived from 6 PET scans in healthy volunteers using the high affinity D2/D3 antagonist ligand [18F]-Fallypride. Brain mRNA expression values for DRD2 gene (coding for D2R) were extracted from the ABA dataset by using the MENGA toolbox. CBF contrast images and the [18F]Fallypride BPND template were segmented into 83 ROIs by using the Desikan-Killiany Atlas. The regional changes in CBF against placebo (∆CBF) were compared with regional BPND values and gene expression maps using multivariate correlations.ResultsFor all antipsychotics, CBF changes in each ROI were directly proportional to [18F]Fallypride non displaceable binding potential (BPND) values (OLA R2= 0.24, HAL R2= 0.61, lowRIS R2= 0.54, highRIS R2= 0.52, all p<0.001) and DRD2 mRNA expression levels (OLA R2= 0.04, HAL R2= 0.15, lowRIS R2= 0.19, highRIS R2= 0.20, all chance likelihood <2%).DiscussionIn the present study, we were able to show that the CBF increase induced by antipsychotic is directly proportional to D2R concentration in the brain, as indexed by PET BPND maps and mRNA expression levels. Interestingly, the association strength between ∆CBF and brain receptor distribution profiles mirrored differential D2R affinity between the tested drugs. Overall, these results indicate that CBF increases after administration of a single dose of antipsychotics actually reflect known pharmacodynamics profile of these compounds. In addition, these results further reinforce previous evidence suggesting the role of D2R blockade as a mechanism behind increased CBF induced by antipsychotics. Finally, CBF is ultimately a functional marker and this work is important in bridging the considerable gap between the pharmacokinetic and pharmacodynamic effects of compounds with unclear brain functional effects like antipsychotics.

Escitalopram and NHT normalized stress-induced anhedonia and molecular neuroadaptations in a mouse model of depression.

Anhedonia is defined as a diminished ability to obtain pleasure from otherwise positive stimuli. Anxiety and mood disorders have been previously associated with dysregulation of the reward system, with anhedonia as a core element of major depressive disorder (MDD). The aim of the present study was to investigate whether stress-induced anhedonia could be prevented by treatments with escitalopram or novel herbal treatment (NHT) in an animal model of depression. Unpredictable chronic mild stress (UCMS) was administered for 4 weeks on ICR outbred mice. Following stress exposure, animals were randomly assigned to pharmacological treatment groups (i.e., saline, escitalopram or NHT). Treatments were delivered for 3 weeks. Hedonic tone was examined via ethanol and sucrose preferences. Biological indices pertinent to MDD and anhedonia were assessed: namely, hippocampal brain-derived neurotrophic factor (BDNF) and striatal dopamine receptor D2 (Drd2) mRNA expression levels. The results indicate that the UCMS-induced reductions in ethanol or sucrose preferences were normalized by escitalopram or NHT. This implies a resemblance between sucrose and ethanol in their hedonic-eliciting property. On a neurobiological aspect, UCMS-induced reduction in hippocampal BDNF levels was normalized by escitalopram or NHT, while UCMS-induced reduction in striatal Drd2 mRNA levels was normalized solely by NHT. The results accentuate the association of stress and anhedonia, and pinpoint a distinct effect for NHT on striatal Drd2 expression.