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Abstract
Substantial evidence suggests that alterations in noradrenergic function contribute to the cognitive impairments of schizophrenia. Activation of post-junctional alpha 2a-adrenergic receptors in the prefrontal cortex by the alpha 2a-selective agonist guanfacine has demonstrated some preliminary benefit in subjects with schizophrenia treated with atypical antipsychotics. alpha 1-adrenergic receptor activity may be less important in mediating the cognitive impairments of schizophrenia. beta-adrenergic receptors may serve as another potential target for cognitive remediation in schizophrenia. However, the potential increase in memory consolidation in schizophrenia patients produced by beta-adrenergic agonists may be outweighed by the impairment in cognitive flexibility and executive functioning produced by beta-adrenergic agonists. Finally, norepinephrine reuptake inhibitors, such as atomoxetine, hold promise as potential cognitive enhancers in schizophrenia because of their ability to indirectly but selectively increase extracellular dopamine concentrations in the prefrontal cortex.
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Affiliation(s)
- Joseph I Friedman
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA.
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52
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Abstract
Although the cathecholamine systems have long been the focus of drug therapy in anxiety and depression, the development of novel drugs specifically aimed at new targets within these traditional neurotransmitter systems and at targets outside of these systems is now propelling the field of drug development in anxiety. A greater understanding of regional brain networks implicated in stress, anxiety, and anxious behaviors has provided localized targets for anxiolytics. Within the serotonin and norepinephrine systems, increased understanding of postsynaptic receptor regulation with chronic treatment and cross-system effects of drug therapy have been critical in furthering our understanding of effective pharmacological interventions. Receptors within the glutamate, gamma-aminobutyric acid, and neuropeptide systems provide a rich diversity of drug targets, both in localization and function. While acknowledging significant clinical and biological differences between the various anxiety disorders, an important aspect of modern neurobiological research is to look for similarities among these disorders, given that they are highly comorbid with each other and often respond to the same spectrum of treatments. Here we review current views on both traditional and new molecular targets in the treatment of anxiety, realizing that the ultimate challenge in effective anxiolytic drug development may be achieving specificity in brain regions important in generating and sustaining anxiety.
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Affiliation(s)
- Justine M Kent
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York, USA
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53
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Moore TL, Killiany RJ, Rosene DL, Prusty S, Hollander W, Moss MB. Impairment of executive function induced by hypertension in the rhesus monkey (Macaca mulatta). Behav Neurosci 2002; 116:387-96. [PMID: 12049319 DOI: 10.1037/0735-7044.116.3.387] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effects of chronic, untreated hypertension on executive function were investigated in a nonhuman primate model of hypertensive cerebrovascular disease. Executive function was assessed with the Conceptual Set-Shifting Task (CSST). a task adapted from the human Wisconsin Card Sorting Test (WCST). Like the WCST, the CSST requires abstraction of a stimulus set, followed by a series of set shifts. Performance on the CSST by 7 young adult monkeys (Macaca mulatta) with surgically induced hypertension was compared with that of 6 normotensive monkeys. The hypertensive group was significantly impaired relative to the normotensive group in abstraction and set shifting. Although the neural basis of this impairment is unclear, evidence from studies with humans and monkeys suggests that the prefrontal cortex may be the locus for this effect of hypertension.
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Affiliation(s)
- Tara L Moore
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Massachusetts 02118, USA.
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54
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Arnsten AF. Stress impairs prefrontal cortical function in rats and monkeys: role of dopamine D1 and norepinephrine alpha-1 receptor mechanisms. PROGRESS IN BRAIN RESEARCH 2001; 126:183-92. [PMID: 11105647 DOI: 10.1016/s0079-6123(00)26014-7] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
MESH Headings
- Adaptation, Physiological
- Amygdala/physiopathology
- Animals
- Attention/physiology
- Calcium Signaling/drug effects
- Cyclic AMP/physiology
- Cyclic AMP-Dependent Protein Kinases/physiology
- Dopamine/physiology
- Haplorhini/physiology
- Haplorhini/psychology
- Helplessness, Learned
- Humans
- Memory Disorders/etiology
- Memory Disorders/physiopathology
- Models, Neurological
- Models, Psychological
- Nerve Tissue Proteins/physiology
- Noise/adverse effects
- Norepinephrine/physiology
- Phosphatidylinositol Diacylglycerol-Lyase
- Prefrontal Cortex/physiopathology
- Rats/physiology
- Rats/psychology
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/physiology
- Receptors, Dopamine D1/drug effects
- Receptors, Dopamine D1/physiology
- Second Messenger Systems/drug effects
- Second Messenger Systems/physiology
- Stress, Physiological/complications
- Stress, Physiological/physiopathology
- Stress, Physiological/psychology
- Type C Phospholipases/physiology
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Affiliation(s)
- A F Arnsten
- Sect. Neurobiology, Yale Medical School, New Haven, CT 06520-8001, USA.
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55
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Stewart LS, McKay BE. Acquisition deficit and time-dependent retrograde amnesia for contextual fear conditioning in agmatine-treated rats. Behav Pharmacol 2000; 11:93-7. [PMID: 10821214 DOI: 10.1097/00008877-200002000-00011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cumulative evidence indicates that the hippocampus plays a time-limited role in contextual learning paradigms. Pharmacological studies have indicated that acquisition of background contextual cues during Pavlovian fear conditioning is dependent upon hippocampal function, whereas early inactivation of the hippocampus after training produces retrograde amnesia. When administered prior to contextual fear conditioning, agmatine (5 and 10 mg/kg, i.p.), an endogenous polyamine and N-methyl-D-aspartate (NMDA) receptor ligand found at excitatory synapses in the hippocampus, impaired the acquisition of contextual fear (measured as defensive freezing 26 hours later) without a reduction in baseline motor activity during training. Furthermore, ascending doses of agmatine were found not to exert analgesic effects on response thresholds to peripheral shock. This negated the possibility that the observed learning deficit resulted from a difference in perceived shock intensity. Post-training agmatine treatment produced a time-dependent impairment of consolidation, with subjects approaching a level of fear equivalent to that of a reference group as the delay of treatment increased (up to 6 hours). Since physiologically high levels of agmatine are able to inhibit NMDA receptor activity, these results suggest that polyamine modulation of NMDA receptors, most likely within the hippocampus, is required for the acquisition and consolidation of contextual fear stimuli.
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Affiliation(s)
- L S Stewart
- Department of Biology, Laurentian University, Sudbury, Ontario, Canada.
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56
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Birnbaum S, Gobeske KT, Auerbach J, Taylor JR, Arnsten AF. A role for norepinephrine in stress-induced cognitive deficits: alpha-1-adrenoceptor mediation in the prefrontal cortex. Biol Psychiatry 1999; 46:1266-74. [PMID: 10560032 DOI: 10.1016/s0006-3223(99)00138-9] [Citation(s) in RCA: 217] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Stress exacerbates many neuropsychiatric disorders associated with prefrontal cortical (PFC) dysfunction. Stress also impairs the working memory functions of the PFC. Although stress research has focused on dopaminergic mechanisms, stress also increases norepinephrine (NE) release in PFC, and intra-PFC infusions of NE alpha-1-adrenoceptor agonists impair working memory. The current study examined whether NE alpha-1-adrenoceptor actions in PFC contribute to stress-induced deficits in working memory performance. METHODS Rats were treated with a pharmacological stressor, FG7142 (30 mg/kg) or vehicle 30 min before testing on a test of spatial working memory, delayed alternation. The alpha-1-adrenoceptor antagonist, urapidil (0.1 microgram/0.5 microL), or saline vehicle, was infused into the PFC 15 min before delayed alternation testing. RESULTS As observed previously, FG7142 significantly impaired the accuracy of delayed alternation performance, and induced a perseverative pattern of responding consistent with PFC dysfunction. FG7142 also slowed motor response times. Infusion of urapidil into the PFC completely reversed the FG7142-induced impairment in delayed alternation performance, but did not alter the slowed motor responding. CONCLUSIONS These findings indicate that alpha-1-adrenoceptor stimulation in the PFC contributes to stress-induced impairments in PFC cognitive functions. These neurochemical actions may contribute to symptoms of working memory impairment, poor attention regulation, or disinhibited behaviors in neuropsychiatric disorders sensitive to stress exposure.
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Affiliation(s)
- S Birnbaum
- Sect. Neurobiology, Yale Medical School, New Haven, CT 06520-8001, USA
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57
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Mao ZM, Arnsten AF, Li BM. Local infusion of an alpha-1 adrenergic agonist into the prefrontal cortex impairs spatial working memory performance in monkeys. Biol Psychiatry 1999; 46:1259-65. [PMID: 10560031 DOI: 10.1016/s0006-3223(99)00139-0] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Stimulation of alpha-2 adrenoceptors in the monkey or rat prefrontal cortex (PFC) has been known to improve spatial working memory (SWM) and stimulation of alpha-1 adrenoceptors in the rat PFC has been reported to impair SWM. The present study attempted to replicate in monkey the rat experiments on alpha-1 adrenoceptor stimulation. METHODS The alpha-1 adrenergic agonist phenylephrine or the alpha-2 adrenergic agonist guanfacine was infused into the dorsolateral prefrontal cortex (dlPFC) of monkeys performing the delayed-response (DR) task, a task of SWM, to see how the drugs affect SWM performance. RESULTS Phenylephrine infusion in dlPFC significantly impaired DR performance, whereas guanfacine improved performance. The effects of both drugs were delay-dependent. Infusions outside dlPFC were ineffective. CONCLUSIONS Stimulation of prefrontal cortical alpha-1 adrenoceptors impairs SWM function in monkeys, consistent with the parallel study in rats, whereas stimulation of alpha-2 adrenoceptors improves SWM, indicating that alpha-1 and alpha-2 adrenoceptors may have opposing roles in the PFC.
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Affiliation(s)
- Z M Mao
- Key Laboratory of Neurobiology, Shanghai Institute of Physiology, Chinese Academy of Sciences, People's Republic of China
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58
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Sirviö J, MacDonald E. Central alpha1-adrenoceptors: their role in the modulation of attention and memory formation. Pharmacol Ther 1999; 83:49-65. [PMID: 10501595 DOI: 10.1016/s0163-7258(99)00017-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Adrenoceptors presently are classified into three main subclasses: alpha1-, alpha2-, and beta-receptors, each with three (perhaps more) subtypes. All three alpha1-adrenoceptor subtypes are present in rat brain. The purpose of this review is to assess the role of alpha1-adrenoceptors in the modulation of synaptic transmission and plasticity, as well as their ability to modulate higher cerebral functions, such as attentional and memory processes. However, since there are no truly subtype-specific agonists or antagonists available at present, it is virtually impossible to allocate a particular central effect to one or other of the subtypes. The activation of alpha1-adrenoceptors reduces the firing probability and glutamate release in the cornu ammonis of the hippocampus. Alpha1-Adrenoceptors may flexibly modulate weak and strong activation of the pyramidal neurones in the neocortex. Alpha1-Adrenoceptors play only a minor role in the modulation of long-term potentiation in the hippocampus, and may influence many brain functions also via non-neuronal mechanisms. since glial cells can express alpha1-adrenoceptors. At the behavioural level, the activation of alpha1-adrenoceptors promotes vigilance and influences working memory and behavioural activation, while having only a minor role in the modulation of long-term memory.
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Affiliation(s)
- J Sirviö
- A.I. Virtanen Institute, University of Kuopio, Department of Neurology, Kuopio University Hospital, Finland
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59
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Marek GJ, Aghajanian GK. 5-HT2A receptor or alpha1-adrenoceptor activation induces excitatory postsynaptic currents in layer V pyramidal cells of the medial prefrontal cortex. Eur J Pharmacol 1999; 367:197-206. [PMID: 10078993 DOI: 10.1016/s0014-2999(98)00945-5] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We compared 5-hydroxytryptamine (5-HT), norepinephrine and dopamine for their efficacy at increasing excitatory postsynaptic current frequency in layer V pyramidal cells from rat medial prefrontal cortical slices. 5-HT, norepinephrine and dopamine increased the excitatory postsynaptic current frequency by 15.9-, 4.5- and 1.7-fold, respectively. Similar to previous results with 5-HT-induced excitatory postsynaptic currents, blockade of mu-opioid receptors, of alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptors and fast Na+ channels suppressed the norepinephrine-induced excitatory postsynaptic currents. The norepinephrine-induced, and in most cases, the dopamine-induced increase in excitatory postsynaptic current frequency was blocked by the alpha1-adrenoceptor antagonist prazosin while the alpha2-adrenoceptor antagonist yohimbine did not block either the norepinephrine- or the 5-HT-induced increase in excitatory postsynaptic currents frequency. The potency of three 5-HT2 receptor antagonists with varying selectivity for 5-HT2A/2B/2C receptors tested against the 5-HT-induced increase in excitatory postsynaptic current frequency are in agreement with the affinity of these drugs for the 5-HT2A receptor. These findings suggest that 5-HT2A receptor or alpha1-adrenoceptor activation enhance neurotransmitter release from a similar subset of glutamate terminals that innervate apical dendrites of layer V pyramidal cells.
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Affiliation(s)
- G J Marek
- Department of Psychiatry, Yale University School of Medicine, Ribicoff Research Facilities of the Connecticut Mental Health Center, New Haven 06508, USA.
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60
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Arnsten AF, Mathew R, Ubriani R, Taylor JR, Li BM. Alpha-1 noradrenergic receptor stimulation impairs prefrontal cortical cognitive function. Biol Psychiatry 1999; 45:26-31. [PMID: 9894572 DOI: 10.1016/s0006-3223(98)00296-0] [Citation(s) in RCA: 193] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Many neuropsychiatric disorders are associated with high levels of noradrenergic turnover, and most antipsychotic medications have alpha-1 adrenoceptor blocking properties, yet little is known about alpha-1 influences on higher cortical function. METHODS The alpha-1 adrenergic agonist, phenylephrine, was infused into the prefrontal cortex (PFC) of rats (0.1 microgram/0.5 microL) performing a spatial working memory task, delayed alternation. The phenylephrine response was challenged with coinfusion of the alpha-1 adrenergic antagonist, uripidil (0.01 microgram), or with a dose of lithium chloride (4 mEq/kg, i.p., 18 hours) known to suppress phosphotidylinositol (PI) turnover, the second messenger pathway coupled to alpha-1 adrenoceptors. RESULTS Phenylephrine infusions in PFC markedly impaired delayed alternation performance. The phenylephrine response was reversed by coinfusion of uripidil, or by pretreatment with lithium, consistent with actions at alpha-1 adrenoceptors coupled to a PI pathway. CONCLUSIONS These findings demonstrate that alpha-1 adrenoceptor stimulation in the PFC impairs cognitive function. Excessive stimulation of alpha-1 adrenoceptors may contribute to PFC deficits (e.g., distractibility, impulsivity) in disorders such as mania, dementia, and anxiety associated with high noradrenergic turnover.
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Affiliation(s)
- A F Arnsten
- Section of Neurobiology, Yale Medical School, New Haven, Connecticut 06520-8001, USA
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61
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Gioanni Y, Thierry AM, Glowinski J, Tassin JP. Alpha1-adrenergic, D1, and D2 receptors interactions in the prefrontal cortex: implications for the modality of action of different types of neuroleptics. Synapse 1998; 30:362-70. [PMID: 9826228 DOI: 10.1002/(sici)1098-2396(199812)30:4<362::aid-syn3>3.0.co;2-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The activation of rat mesocortical dopaminergic (DA) neurons evoked by the electrical stimulation of the ventral tegmental area (VTA) induces a marked inhibition of the spontaneous activity of prefrontocortical cells. In the present study, it was first shown that systemic administration of either clozapine (a mixed antagonist of D1, D2, and alpha1-adrenergic receptors) (3-5 mg/kg, i.v.), prazosin (an alpha1-adrenergic antagonist) (0.2 mg/kg, i.v.), or sulpiride (a D2 antagonist) (30 mg/kg, i.v.), but not SCH 23390 (a D1 antagonist) (0.2 mg/kg, i.v.), reversed this cortical inhibition. Second, it was found that following the systemic administration of prazosin, the VTA-induced cortical inhibition reappeared when either SCH 23390 or sulpiride was applied by iontophoresis into the prefrontal cortex. Third, it was seen that, whereas haloperidol (0.2 mg/kg, i.v.), a D2 antagonist which also blocks alpha1-adrenergic receptors, failed to reverse the VTA-induced inhibition, the systemic administration of haloperidol plus SCH 23390 (0.2 mg/kg, i.v.) blocked this inhibition. Finally, it was verified that the cortical inhibitions obtained following treatments with either "prazosin plus sulpiride" or "prazosin plus SCH 23390" were blocked by a superimposed administration of either SCH 23390 or sulpiride, respectively. These data indicate that complex interactions between cortical D2, D1, and alpha1-adrenergic receptors are involved in the regulation of the activity of prefrontocortical cells innervated by the VTA neurons. They confirm that the physiological stimulation of cortical alpha1-adrenergic receptors hampers the functional activity of cortical D1 receptors and suggest that the stimulations of cortical D1 and D2 receptors exert mutual inhibition on each other's transmission.
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Affiliation(s)
- Y Gioanni
- INSERM U 114, Chaire de Neuropharmacologie, Collège de France, Paris
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62
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Affiliation(s)
- A F Arnsten
- Section of Neurobiology, Yale University School of Medicine, New Haven, CT 06520-8001, USA.
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