Life Sciences Commons^™

The Marine Sponge Metabolite Mycothiazole: A Novel Prototype Mitochondrial Complex I Inhibitor., J Brian Morgan, Fakhri Mahdi, Yang Liu, Veena Coothankandaswamy, Mika B Jekabsons, Tyler A. Johnson, Koneni V Sashidhara, Phillip Crews, Dale G Nagle, Yu-Dong Zhou

Tyler Johnson

A natural product chemistry-based approach was applied to discover small-molecule inhibitors of hypoxia-inducible factor-1 (HIF-1). A Petrosaspongia mycofijiensis marine sponge extract yielded mycothiazole (1), a solid tumor selective compound with no known mechanism for its cell line-dependent cytotoxic activity. Compound 1 inhibited hypoxic HIF-1 signaling in tumor cells (IC(50) 1nM) that correlated with the suppression of hypoxia-stimulated tumor angiogenesis in vitro. However, 1 exhibited pronounced neurotoxicity in vitro. Mechanistic studies revealed that 1 selectively suppresses mitochondrial respiration at complex I (NADH-ubiquinone oxidoreductase). Unlike rotenone, MPP(+), annonaceous acetogenins, piericidin A, and other complex I inhibitors, mycothiazole is a mixed polyketide/peptide-derived compound …

Rotating Magnets Produce A Prompt Analgesia Effect In Rats, Zhong Chen, Hui Ye, Haiyun Xu, Shukang An, Anmin Jin, Chusong Zhou, Shaoan Yang

Hui Ye

The beneficial effects of chronic/repeated magnetic stimulation on humans have been examined in previous studies. Although pain relief effects have been reported several weeks after magnetic treatment, no report is available regarding the prompt effect of magnetic stimulations. In this study, a novel apparatus was developed to generate time-varying magnetic fields with rotating magnets. Adult, conscious rats were exposed to the rotating magnets in a posture in which their spines were parallel to the induced electric current. The magnetic field suppressed the paw withdrawal reflex in the anesthetized rats, and the suppression effect disappeared 5 minutes after magnets stopped rotating. …

Infection Of Peripancreatic Lymph Nodes But Not Islets Precedes Kilham Rat Virus-Induced Diabetes In Bb/Wor Rats, David Brown, Raymond Welsh, Arthur Like

David C. Brown

A parvovirus serologically identified as Kilham rat virus (KRV) reproducibly induces acute type I diabetes in diabetes-resistant BB/Wor rats. The tissue tropism of KRV was investigated by in situ hybridization with a digoxigenin-labelled plasmid DNA probe containing approximately 1.6 kb of the genome of the UMass isolate of KRV. Partial sequencing of the KRV probe revealed high levels of homology to the sequence of minute virus of mice (89%) and to the sequence of H1 (99%), a parvovirus capable of infecting rats and humans. Of the 444 bases sequenced, 440 were shared by H1. KRV mRNA and DNA were readily …

Biaxial Failure Properties Of Planar Living Tissue Equivalents, Kristen Billiar, Angela Throm, Margo Frey

Kristen L. Billiar

Quantification of the mechanical properties of living tissue equivalents (LTEs) is essential for assessing their ultimate functionality as tissue substitutes, yet their delicate nature makes failure testing problematic. For this study, we evaluated the validity of using an inflation device for quantifying the biaxial tensile failure properties of extremely delicate fibroblast-populated collagen gels (CGs) and fibrin gels (FGs). Small samples were circularly clamped and then inflated until rupture. Each sample assumed an approximately spherical shape and burst at its center indicating effective clamping. After two weeks in culture, all LTEs tested were fragile, but the FGs were significantly stronger and …

Quaking Regulates Hnrnpa1 Expression Through Its 3' Utr In Oligodendrocyte Precursor Cells, Nancy Zearfoss, Carina Clingman, Brian Farley, Lisa Mccoig, Sean Ryder

Sean P. Ryder

In mice, Quaking (Qk) is required for myelin formation; in humans, it has been associated with psychiatric disease. QK regulates the stability, subcellular localization, and alternative splicing of several myelin-related transcripts, yet little is known about how QK governs these activities. Here, we show that QK enhances Hnrnpa1 mRNA stability by binding a conserved 3' UTR sequence with high affinity and specificity. A single nucleotide mutation in the binding site eliminates QK-dependent regulation, as does reduction of QK by RNAi. Analysis of exon expression across the transcriptome reveals that QK and hnRNP A1 regulate an overlapping subset of transcripts. Thus, …

Comparison Between Coated Vs. Uncoated Suture Middle Cerebral Artery Occlusion In The Rat As Assessed By Perfusion/Diffusion Weighted Imaging, James Bouley, Marc Fisher, Nils Henninger

Nils Henninger

Differences among models in the temporal evolution of ischemia after middle cerebral artery occlusion (MCAO) in rats may considerably influence the results of experimental treatment studies. Using diffusion and perfusion imaging, we compared the spatiotemporal evolution of ischemia in Sprague-Dawley rats after permanent MCAO (pMCAO) with different types of sutures. Male Sprague-Dawley rats were randomly assigned to pMCAO produced with either 4-0 silicone coated (n=8), or 3-0 uncoated monofilaments (n=8). Serial determination of quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) maps were performed up to 3 h after pMCAO. Lesion volumes were calculated by using previously validated …

Characterizing Tissue Fate After Transient Cerebral Ischemia Of Varying Duration Using Quantitative Diffusion And Perfusion Imaging, Juergen Bardutzky, Qiang Shen, Nils Henninger, Stefan Schwab, Timothy Duong, Marc Fisher

Nils Henninger

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the effects of reperfusion on ischemic lesion evolution and pixel-by-pixel apparent diffusion coefficient-cerebral blood flow (ADC-CBF) dynamics of core and mismatch tissues after 35, 60, and 95 minutes of transient focal ischemia in rats (n=28). METHODS: Serial diffusion-, perfusion-, and T2-weighted imaging were performed up to 24 hours. The evolution of the magnetic resonance image-derived lesion volume was investigated and ADC-CBF scatterplots were performed to prospectively characterize the ADC and CBF dynamics of core and mismatch tissues with different fates. For comparison, similar analysis was performed on a historical …

Comparison Of Ischemic Lesion Evolution In Embolic Versus Mechanical Middle Cerebral Artery Occlusion In Sprague Dawley Rats Using Diffusion And Perfusion Imaging, Nils Henninger, Kenneth Sicard, Karl Schmidt, Juergen Bardutzky, Marc Fisher

Nils Henninger

BACKGROUND AND PURPOSE: Differences among models in the temporal evolution of ischemia after middle cerebral artery occlusion (MCAO) in rats may considerably influence the results of experimental stroke research. Using diffusion and perfusion imaging, we compared the spatiotemporal evolution of ischemia in Sprague Dawley rats after permanent suture MCAO (sMCAO; n=8) and embolic MCAO (eMCAO; n=8).

METHODS: Serial measurements of quantitative cerebral blood flow (CBF) and the apparent diffusion coefficient (ADC) were performed up to 180 minutes after MCAO. ADC and CBF values within 5 different brain regions were analyzed. ADC and CBF lesion volumes were calculated by using previously …

Ischemic Lesion Volume Determination On Diffusion Weighted Images Vs. Apparent Diffusion Coefficient Maps, Bernt Bratane, Birgül Bastan, Marc Fisher, James Bouley, Nils Henninger

Nils Henninger

Though diffusion weighted imaging (DWI) is frequently used for identifying the ischemic lesion in focal cerebral ischemia, the understanding of spatiotemporal evolution patterns observed with different analysis methods remains imprecise. DWI and calculated apparent diffusion coefficient (ADC) maps were serially obtained in rat stroke models (MCAO): permanent, 90 min, and 180 min temporary MCAO. Lesion volumes were analyzed in a blinded and randomized manner by 2 investigators using (i) a previously validated ADC threshold, (ii) visual determination of hypointense regions on ADC maps, and (iii) visual determination of hyperintense regions on DWI. Lesion volumes were correlated with 24 hour 2,3,5-triphenyltetrazoliumchloride …

The Proteasome Inhibitor Velcade Reduces Infarction In Rat Models Of Focal Cerebral Ischemia, Nils Henninger, Kenneth Sicard, James Bouley, Marc Fisher, Nancy Stagliano

Nils Henninger

The potential neuroprotective effects of VELCADE were investigated in two different models of focal cerebral ischemia. For time-window assessment, male Wistar-Kyoto rats were treated with 0.2 mg/kg VELCADE at 1, 2, or 3 h after the induction of permanent middle cerebral artery occlusion (MCAO) using the suture occlusion method (experiment 1). To evaluate effects in a different model, male Sprague-Dawley rats received 0.2 mg/kg VELCADE after embolic MCAO (experiment 2). Infarct volume was calculated based on TTC-staining 24 h postischemia and whole blood proteasome activity was fluorometrically determined in both experiments at baseline, 1 and 24 h post-MCAO. In experiment …

Laser Doppler Flowmetry Predicts Occlusion But Not Tpa-Mediated Reperfusion Success After Rat Embolic Stroke, Nils Henninger, James Bouley, Bernt Bratane, Birgül Bastan, Meghan Shea, Marc Fisher

Nils Henninger

BACKGROUND AND PURPOSE: Laser Doppler flowmetry (LDF) is increasingly used to assess adequate occlusion after embolic stroke (ES) in rats. METHODS: Employing LDF, relative regional cerebral blood flow (rCBF) was continuously monitored during the first 2 h following ES and correlated with 24 h 2,3,5-triphenyltetrazolium chloride (TTC)-staining of corrected infarct volume. In a preliminary experiment (n=18), it was demonstrated that rCBF-reduction to 37% or less of baseline correctly identified occlusion success in the suture middle cerebral artery occlusion (sMCAO) model. Using the same methodology, we then assessed whether LDF allowed for identification of animals with successful ES (experiment 2, n=26) …

Visualization Of Clot Lysis In A Rat Embolic Stroke Model: Application To Comparative Lytic Efficacy, Ronn Walvick, Bernt Bratane, Nils Henninger, Kenneth Sicard, James Bouley, Zhanyang Yu, Eng Lo, Xiaoying Wang, Marc Fisher

Nils Henninger

BACKGROUND AND PURPOSE: The purpose of this study was to develop a novel MRI method for imaging clot lysis in a rat embolic stroke model and to compare tissue plasminogen activator (tPA)-based clot lysis with and without recombinant Annexin-2 (rA2). METHODS: In experiment 1 we used in vitro optimization of clot visualization using multiple MRI contrast agents in concentrations ranging from 5 to 50 muL in 250 muL blood. In experiment 2, we used in vivo characterization of the time course of clot lysis using the clot developed in the previous experiment. Diffusion, perfusion, angiography, and T1-weighted MRI for clot …

Differences In Ischemic Lesion Evolution In Different Rat Strains Using Diffusion And Perfusion Imaging, Juergen Bardutzky, Qiang Shen, Nils Henninger, James Bouley, Timothy Duong, Marc Fisher

Nils Henninger

BACKGROUND AND PURPOSE: Interstrain differences in the temporal evolution of ischemia after middle cerebral artery occlusion (MCAO) in rats may considerably influence the results of experimental stroke research. We investigated, in 2 commonly used rat strains (Sprague-Dawley [SD] and Wistar-Kyoto [WK]), the spatiotemporal evolution of ischemia after permanent suture MCAO using diffusion and perfusion imaging.

METHODS: Serial measurements of quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) were performed up to 210 min after MCAO. Lesion volumes were calculated by using previously established viability thresholds and correlated with infarct volume defined by 2,3,5-triphenyltetrazolium chloride staining 24 hours after …

Normobaric Hyperoxia And Delayed Tpa Treatment In A Rat Embolic Stroke Model, Nils Henninger, Bernt Bratane, Birgül Bastan, James Bouley, Marc Fisher

Nils Henninger

In a rat embolic stroke (eMCAO) model, the effects of 100% normobaric hyperoxia (NBO) with delayed recombinant tissue plasminogen activator (tPA) administration on ischemic lesion size and safety were assessed by diffusion- and perfusion (PWI)-weighted magnetic resonance imaging. NBO or room air (Air) by a face mask was started at 30 mins posteMCAO and continued for 3.5 h. Tissue plasminogen activator or saline was started at 3 h posteMCAO. Types and location of hemorrhagic transformation were assessed at 24 h and a spectrophotometric hemoglobin assay quantified hemorrhage volume at 10 h. In NBO-treated animals the apparent diffusion coefficient/PWI mismatch persisted …

Differential Recovery Of Multimodal Mri And Behavior After Transient Focal Cerebral Ischemia In Rats, Kenneth Sicard, Nils Henninger, Marc Fisher, Timothy Duong, Craig Ferris

Nils Henninger

The association between recovery of brain function and behavior after transient cerebral ischemia in animals and humans is incompletely characterized. Quantitative diffusion- (DWI), perfusion- (PWI), T(2)-weighted (T(2)WI), and functional magnetic resonance imaging (fMRI) were performed before, during, and up to 1 day after 20-mins transient middle cerebral artery occlusion (tMCAO; n=6) or sham operation (n=6) in male Sprague-Dawley rats. Viability thresholds were employed to calculate diffusion, perfusion, and T(2) lesion volumes. Region of interest analysis was used to evaluate structural and functional MR signal changes within the sensorimotor network, which were then related to corresponding behavioral measures. Post-mortem 2,3,5-triphenyltetrazolium chloride …

Parathyroid-Responsive Modifications In The Nuclear Matrix Of Ros 17/2.8 Rat Osteosarcoma Cells, Joseph Bidwell, Andre Van Wijnen, Chaitali Banerjee, Edward Fey, Harold Merriman, Sheldon Penman, Janet Stein, Jane Lian, Gary Stein

Harold L. Merriman

PTH is a mediator of skeletal development and remodeling that influences gene expression in osteoblastic cells. It is well established that PTH modulates the activity of membrane-associated second messenger signal transduction pathways. In these studies we have addressed the potential contribution of components of cell structure to the integration of PTH-related regulatory signals that influence the expression of bone cell genes. Chronic treatment of ROS 17/2.8 rat osteosarcoma cells with PTH is accompanied by changes in gene expression that are at least in part transcriptionally controlled. To explore the involvement of nuclear architecture in PTH-responsive modifications in gene expression, we …

Subnuclear Distribution Of The Vitamin D Receptor, Joseph Bidwell, Andre Van Wijnen, Edward Fey, Harold Merriman, Sheldon Penman, Janet Stein, Gary Stein, Jane Lian

Harold L. Merriman

The subnuclear distribution of the vitamin D receptor was investigated to begin addressing the contribution of nuclear architecture to vitamin D-responsive control of gene expression in ROS 17/2.8 rat osteosarcoma cells. The nuclear matrix is an anastomosing network of filaments that is functionally associated with DNA replication, transcription, and RNA processing. The representation of vitamin D receptor in the nuclear matrix and nonmatrix nuclear fractions was determined by the combined application of 1) sequence-specific interactions with the vitamin D receptor binding element of the rat bone-specific osteocalcin gene promoter and 2) Western blot analysis. Both methods confirmed the presence of …

The Tissue-Specific Nuclear Matrix Protein, Nmp-2, Is A Member Of The Aml/Cbf/Pebp2/Runt Domain Transcription Factor Family: Interactions With The Osteocalcin Gene Promoter, Harold Merriman, Andre Van Wijnen, Scott Hiebert, Joseph Bidwell, Edward Fey, Jane Lian, Janet Stein, Gary Stein

Harold L. Merriman

The nuclear matrix protein, NMP-2, was originally identified as an osteoblast-specific DNA-binding complex localized exclusively to the nuclear matrix. NMP-2 was shown to recognize two binding sites, site A (nt-605 to -599) and site B (nt -441 to -435), in the rat bone-specific osteocalcin gene promoter. This study shows that the NMP-2 binding sites A and B as well as a third NMP-2 binding site (nt -135 to -130) constitute a consensus sequence, ATGCTGGT, and represent an AML-1 recognition motif. AML-1 is a member of the AML transcription factor family which is associated with acute myelogenous leukemia and binds to …

Amphetamine-Induced Decreases In Dopamine Transporter Surface Expression Are Protein Kinase C-Independent, Ekaterina Boudanova, Deanna Navaroli, Haley Melikian

Haley Melikian

Amphetamine (AMPH) is a potent dopamine (DA) transporter (DAT) inhibitor that markedly increases extracellular DA levels. In addition to its actions as a DAT antagonist, acute AMPH exposure induces DAT losses from the plasma membrane, implicating transporter-specific membrane trafficking in amphetamine's actions. Despite reports that AMPH modulates DAT surface expression, the trafficking mechanisms leading to this effect are currently not defined. We recently reported that DAT residues 587-596 play an integral role in constitutive and protein kinase C (PKC)-accelerated DAT internalization. In the current study, we tested whether the structural determinants required for PKC-stimulated DAT internalization are necessary for AMPH-induced …

Developmental Expression Of A Candidate Mullerian Inhibiting Substance Type Ii Receptor, Jose Teixeira, Wei He, Paresh Shah, Nobuyuki Morikawa, Mary Lee, Elizabeth Catlin, Peter Hudson, John Wing, David Maclaughlin, Patricia Donahoe

Mary M. Lee

We have isolated a candidate Mullerian inhibiting substance (MIS) type II receptor complementary DNA from an embryonic rat urogenital ridge library and have studied its binding to MIS, its developmental pattern of expression and tissue distribution. By in situ hybridization with a full-length riboprobe, the receptor is expressed in the mesenchymal cells surrounding the Mullerian duct at embryonic days 14, 15, and 16 and in tubular and follicular structures of the rat fetal gonads. Expression of the messenger RNA was also seen in the granules cells and seminiferous tubules of pubertal gonads. Northern analysis revealed that the MIS type II …

Developmentally Regulated Polyadenylation Of Two Discrete Messenger Ribonucleic Acids For Mullerian Inhibiting Substance, Mary Lee, Richard Cate, Patricia Donahoe, Gerald Waneck

Mary M. Lee

Mullerian inhibiting substance (MIS) is a 140-kilodalton homodimeric glycoprotein that causes regression of the Mullerian ducts in male embryos, and may also have a role in both males and females in the regulation of germ cell maturation. We examined the ontogeny of MIS messenger RNA (mRNA) in rat testes from midgestation through adulthood and found two discrete MIS mRNA species that are developmentally regulated. The larger 2.0-kilobase species is abundant at embryonic day 14, then decreases in late gestation, and is barely detectable after birth. The smaller 1.8-kilobase species is first noted at embryonic day 18 and is the major …

Mullerian-Inhibiting Substance Inhibits Rat Leydig Cell Regeneration After Ethylene Dimethanesulphonate Ablation, Antonio Salva, Matthew Hardy, Xiufeng Wu, Chantal Sottas, David Maclaughlin, Patricia Donahoe, Mary Lee

Mary M. Lee

The postnatal development of Leydig cell precursors is postulated to be controlled by Sertoli cell secreted factors, which may have a determinative influence on Leydig cell number and function in sexually mature animals. One such hormone, Mullerian inhibiting substance (MIS), has been shown to inhibit DNA synthesis and steroidogenesis in primary Leydig cells and Leydig cell tumor lines. To further delineate the effects of MIS on Leydig cell proliferation and steroidogenesis, we employed the established ethylene dimethanesulphonate (EDS) model of Leydig cell regeneration. Following EDS ablation of differentiated Leydig cells in young adult rats, recombinant MIS or vehicle was delivered …

Mullerian Inhibiting Substance Ontogeny And Its Modulation By Follicle-Stimulating Hormone In The Rat Testes, Tatsuo Kuroda, Mary Lee, Christopher Haqq, David Powell, Thomas Manganaro, Patricia Donahoe

Mary M. Lee

Mullerian Inhibiting Substance (MIS) production in rat testes from the late fetal to the adult period and its modulation by gonadotropins in neonatal testes were studied using immunohistochemistry, northern analysis, and a graded organ culture bioassay for MIS. The intense immunohistochemical staining for MIS seen in fetal and newborn testes began to decrease gradually after the third postnatal day, then decreased dramatically on the fifth postnatal day. MIS immunohistochemical activity was then present at a low level until about the 20th postnatal day, after which it was barely detectable. The testes from rats treated with FSH at birth showed a …

Mullerian Inhibiting Substance Inhibits Testosterone Synthesis In Adult Rats, V. Sriraman, E. Niu, J. Matias, Patricia Donahoe, David Maclaughlin, Matthew Hardy, Mary Lee

Mary M. Lee

Mullerian inhibiting substance (MIS) is a gonadal hormone that causes regression of the Mullerian ducts during male sexual differentiation. Postnatally, MIS inhibits the proliferation and differentiation of immature Leydig cells, and transgenic mice that overexpress MIS have decreased serum testosterone concentrations. To elucidate the effects of MIS on androgen regulation in the postnatal testis, we examined testosterone synthesis in adult Sprague-Dawley rats following intratesticular and intraperitoneal injections of MIS. Intratesticular MIS injection achieved high local concentrations of MIS (574.0 +/- 60.0 ng/mL) at 4 hours, with a corresponding decline in serum testosterone concentrations to 0.7 +/- 0.1 ng/mL, compared to …

Androgen Profiles During Pubertal Leydig Cell Development In Mice, Xiufeng Wu, Ramamani Arumugam, Ningning Zhang, Mary Lee

Mary M. Lee

Postnatal Leydig cell (LC) development in mice has been assumed empirically to resemble that of rats, which have characteristic hormonal profiles at well-defined maturational stages. To characterize the changes in LC function and gene expression in mice, we examined reproductive hormone expression from birth to 180 days, and quantified in vivo and in vitro production of androgens during sexual maturation. Although the overall plasma androgen and LH profiles from birth through puberty were comparable to that of rats, the timing of developmental changes in androgen production and steroidogenic capacity of isolated LCs differed. In mice, onset of androgen biosynthetic capacity, …

Mullerian-Inhibiting Substance Type Ii Receptor Expression And Function In Purified Rat Leydig Cells, Mary Lee, C. Seah, P. Masiakos, Chantal Sottas, F. Preffer, Patricia Donahoe, David Maclaughlin, Matthew Hardy

Mary M. Lee

Mullerian-inhibiting substance (MIS), a gonadal hormone in the transforming growth factor-beta superfamily, induces Mullerian duct involution during male sexual differentiation. Mice with null mutations of the MIS ligand or receptor develop Leydig cell hyperplasia and neoplasia in addition to retained Mullerian ducts, whereas MIS-overexpressing transgenic mice have decreased testosterone concentrations and Leydig cell numbers. We hypothesized that MIS directly modulates Leydig cell proliferation and differentiated function in the maturing testis. Therefore, highly purified rat Leydig and Sertoli cells were isolated to examine cell-specific expression, binding, and function of the MIS type II receptor. These studies revealed that this receptor is …

Isolation Of The Rat Gene For Mullerian Inhibiting Substance, Christopher Haqq, Mary Lee, Richard Tizard, Mark Wysk, Janice Demarinis, Patricia Donahoe, Richard Cate

Mary M. Lee

Mullerian inhibiting substance (MIS), a testicular glycoprotein also known as anti-Mullerian hormone, plays a key role in male sexual development by causing regression of the Mullerian duct, the anlagen of the uterus, the Fallopian tubes, and part of the vagina. MIS is also expressed in the postnatal ovary, but its precise function is still not known. We report here the complete nucleotide sequence of the rat MIS gene. Rat MIS is encoded in five exons and is synthesized as a precursor of 553 amino acids, containing a 24-amino-acid leader. Based on homology with human MIS, we predict that the rat …

Mullerian Inhibiting Substance Messenger Ribonucleic Acid Expression In Granulosa And Sertoli Cells Coincides With Their Mitotic Activity, Seiichi Hirobe, Wei He, Mary Lee, Patricia Donahoe

Mary M. Lee

In males, Mullerian inhibiting substance (MIS) mRNA was first detected on the medial aspect of the urogenital ridge early on the morning of day 13 of gestation before testicular differentiation was evident, and localized to the more obvious Sertoli cells later on embryonic day 13. MIS transcripts remained at maximal levels between 14.5 and 17.5 days gestation, while the Mullerian duct involutes, and remained high until birth. MIS gene expression decreased progressively after birth and, as germ cell meiosis increased, became barely detectable in the Sertoli cells of the seminiferous tubules. In female rats, MIS mRNA was first detected in …

Spatial And Temporal Response Patterns On The Eight-Arm Radial Maze, Robert H.I. Dale

Robert H. I. Dale

Six maze-experienced hooded rats were timed during five trials on which they collected water from all arms of an eight-arm radial maze, then made five more choices. All subjects frequently exhibited a “task-completion pause:” The subjects rarely spent more than 1 sec in the center of the maze between choices until they had entered all eight arms, then stopped in the center of the maze. In contrast, the time spent in each arm gradually increased until all of the water had been obtained, then decreased slightly. Four subjects began every trial by choosing eight consecutive adjacent arms. The task-completion pause …

The Relative Attenuation Of Self-Stimulation, Eating And Drinking Produced By Dopamine-Receptor Blockade, E. T. Rolls, B. J. Rolls, P. H. Kelly, S. G. Shaw, R. J. Wood, Robert H.I. Dale

Robert H. I. Dale

Spiroperidol, which blocks dopamine (DA) receptors, attenuated self-stimulation of the nucleus accumbens, septal area, hippocampus, anterior hypothalamus and ventral tegmental area. Dopamine is thus involved in self-stimulation of many sites (in addition to the lateral hypothalamus). The attenuation was not a simple motor impairment of the speed of bar-pressing in that the nucleus accumbens and septal self-stimulation rates were lower than those in treated animals self-stimulating at other sites (Experiment 1). Feeding was partly attenuated, and drinking was much less attenuated by the spiroperidol. Since the rats bar-pressed for brain- stimulation reward, chewed pellets to eat, and licked a tube …