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Vedantham K, Brunet A, Neylan TC, Weiss DS, Mannar CR. Neurobiological findings in posttraumatic stress disorder: a review. DIALOGUES IN CLINICAL NEUROSCIENCE 2012. [PMID: 22033551 PMCID: PMC3181587 DOI: 10.31887/dcns.2000.2.1/kvedantham] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Since posttraumatic stress disorder (PTSD) was first recognized as a psychiatric disorder, it has generated a great deal of scientific interest. Recent studies on the neurobiology of PTSD provide evidence that PTSD is biologically distinct from other types of traumatic and nontraumatic stress responses. This paper reviews three important directions of neurobiological research in PTSD: noradrenergic axis changes and associated alterations in autonomic responsivity neuroendocrine changes involving the hypothalamic-pituitary-adrenocortical (HPA) axis, and neuroanatomy changes involving the hippocampus. Each section reviews the salient aspects of preclinical research on the biology of stress and their bearing on the understanding of PTSD, and summarizes prominent findings from clinical biological studies of PTSD, Tentative models that integrate current findings from the clinical study of PTSD are reviewed. To conclude, the important methodological and empirical issues that need to be addressed by future studies are indicated.
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Affiliation(s)
- K Vedantham
- Department of Psychiatry, University of California, San Francisco; and Department of Veterans Affairs, Medical Center, San Francisco, Calif, USA; Acknowledges fellowship support from the Program for Minority Research Training in Psychiatry (PMRTP), which is funded by the National Institute of Mental Health and administered by the American Psychiatric Association
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Booze RM, Wallace DR, Silvers JM, Strupp BJ, Snow DM, Mactutus CF. Prenatal cocaine exposure alters alpha2 receptor expression in adolescent rats. BMC Neurosci 2006; 7:33. [PMID: 16620392 PMCID: PMC1513240 DOI: 10.1186/1471-2202-7-33] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Accepted: 04/18/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prenatal cocaine exposure produces attentional deficits which to persist through early childhood. Given the role of norepinephrine (NE) in attentional processes, we examined the forebrain NE systems from prenatal cocaine exposed rats. Cocaine was administered during pregnancy via the clinically relevant intravenous route of administration. Specifically, we measured alpha2-adrenergic receptor (alpha2-AR) density in adolescent (35-days-old) rats, using [3H]RX821002 (5 nM). RESULTS Sex-specific alterations of alpha2-AR were found in the hippocampus and amygdala of the cocaine-exposed animals, as well as an upregulation of alpha2-AR in parietal cortex. CONCLUSION These data suggest that prenatal cocaine exposure results in a persistent alteration in forebrain NE systems as indicated by alterations in receptor density. These neurochemical changes may underlie behavioral abnormalities observed in offspring attentional processes following prenatal exposure to cocaine.
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Affiliation(s)
- Rosemarie M Booze
- Department of Psychology, University of South Carolina Columbia, SC 29208, USA
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina Columbia, SC 29208, USA
| | - David R Wallace
- Department of Pharmacology and Physiology, Oklahoma State University, College of Osteopathic Medicine Tulsa, OK 74017-1898, USA
| | - Janelle M Silvers
- Department of Psychology, University of South Carolina Columbia, SC 29208, USA
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina Columbia, SC 29208, USA
| | - Barbara J Strupp
- Division of Nutritional Sciences and Department of Psychology, Cornell University Ithaca, NY 14853-6301, USA
| | - Diane M Snow
- Department of Anatomy and Neurobiology, The University of Kentucky, Lexington, KY 40536-0298, USA
| | - Charles F Mactutus
- Department of Psychology, University of South Carolina Columbia, SC 29208, USA
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Foltz TL, Snow DM, Strupp BJ, Booze RM, Mactutus CF. Prenatal intravenous cocaine and the heart rate-orienting response: a dose-response study. Int J Dev Neurosci 2004; 22:285-96. [PMID: 15380828 DOI: 10.1016/j.ijdevneu.2004.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Revised: 05/27/2004] [Accepted: 05/27/2004] [Indexed: 10/26/2022] Open
Abstract
Attentional dysfunction is a persistent behavioral abnormality that is emerging as one of the cardinal features in the investigations of the teratogenic effects of cocaine in humans and rodents. The present study sought to extend this work by using a dose-response design with an alternate strain of rat. Virgin Long-Evans female rats, implanted with an IV access port prior to breeding were administered saline, 0.5, 1.0, or 3.0 mg/kg of cocaine HCl from gestational day (GD) GD8-21 (1x per day-GD8-14, 2x per day-GD15-21). Cocaine had no significant effect on maternal or litter parameters. At 14-15 days of age, 1 male and 1 female from each litter were tested to evaluate the heart rate orienting response (HR-OR). Following 20 min for acclimation, pups were presented an olfactory stimulus for 20s per trial, across four trials, and with an intertrial interval of 2 min. The initial baseline HR was not significantly different across the treatment groups, although cocaine did alter the stability of the QRS complex duration. The magnitude of the HR-OR averaged across trials increased as a linear function of dosage of cocaine. A more complex (quadratic) interaction between cocaine dose and sex of the offspring was also noted. When examined across trials, the controls failed to display any significant within-session variation in the HR-OR; in contrast all of the prenatal cocaine treated groups displayed either sensitization (low and high dose) or habituation of the response (middle dose). Analysis of the peak HR-OR confirmed that the controls were indeed displaying the response on at least one trial of the session, albeit not consistently on any specific trial. The more vigorous HR-OR of the prenatal cocaine groups, relative to vehicle controls, most likely reflects an alteration in development of the neural basis of response; as previously shown, the most vigorous response to the olfactory stimulus is seen early (12 days of age) and progressively decreases across the preweaning period. In sum, prenatal exposure to cocaine, at least when administered by the IV route, provides reproducible alterations in attentional processes, as indexed by the noradrenergically-mediated HR-OR. The documentation of a linear dose-response function suggests that there is likely no threshold for the drug-induced alteration. Moreover, the sex of the animal also appears to play some role in the nature of the expression of the altered HR-OR.
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Affiliation(s)
- Tara L Foltz
- Department of Biology, University of Kentucky, Lexington, KY, USA
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Mactutus CF. Prenatal intravenous cocaine adversely affects attentional processing in preweanling rats. Neurotoxicol Teratol 1999; 21:539-50. [PMID: 10492388 DOI: 10.1016/s0892-0362(99)00024-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Perhaps the sole, clinically reported, deficit in infants of women that abused cocaine (COC) during pregnancy that persists through early childhood is that of an attentional disorder. Using the heart rate orienting response (HR-OR), a putative valid and reliable measure of attention, we examined the offspring of rats exposed to COC in utero via the clinically relevant intravenous (IV) route. Sprague-Dawley females, implanted with IV access ports prior to breeding, were administered saline or 3 mg/kg COC HC1, 1X/day on gestational day (GD) 8-14 and 2X/day on GD15-21. No significant effects of prenatal COC were apparent for maternal or litter parameters. Six pups/litter were tested: one of each sex on postnatal day (PD) 12, PD16, and PD21. Following 20 min of adaptation, pups were exposed to a novel odor (20 s amyl acetate) for a set of four acquisition trials; after a 4-h retention interval, the same procedure was again employed. At PD12, both prenatal COC and control pups demonstrated a significant HR-OR on the acquisition trials and both groups showed significant within-session habituation. Across the 4-h retention interval, prenatal COC-exposed pups showed habituation whereas control pups did not. At PD16, the magnitude of the HR-OR was significantly greater in prenatal COC-exposed pups relative to control pups. Within-session habituation also characterized the HR-OR of the COC, but not control, pups. For the retention data, within-subject and regression analyses suggested the COC-exposed pups displayed greater between and within-session habituation, respectively. At PD21, the prenatal COC-treated pups displayed an HR-OR that did not habituate across acquisition trials; the control pups displayed a significant HR-OR only during the initial 5 s of the first two trials. During the retention trials, regression analyses again suggested the COC-exposed pups displayed greater evidence of within-session habituation. Collectively, these data demonstrate that prenatal exposure to COC alters attention throughout the preweanling period of development. Given the putative role of norepinephrine, but not dopamine or serotonin, in central mediation of the HR-OR of preweanling rats, the effects of prenatal IV COC exposure in this task are consistent with a noradrenergically based attentional disorder.
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Affiliation(s)
- C F Mactutus
- College of Pharmacy, Tobacco and Health Research Institute, Graduate Center for Toxicology, and the Department of Psychology, University of Kentucky, Lexington 40546-0236, USA.
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Abstract
There is considerable preclinical evidence for a relationship between noradrenergic brain systems and behaviors associated with stress and anxiety. The majority of noradrenergic neurons are located in the locus coeruleus (pons), with projections throughout the cerebral cortex and multiple subcortical areas, including hippocampus, amygdala, thalamus, and hypothalamus. This neuroanatomical formation of the noradrenergic system makes it well suited to rapidly and globally modulate brain function in response to changes in the environment, as occurs during the presentation of stressors. Stress exposure is associated with an increase in firing of the locus coeruleus and with associated increased release and turnover of norepinephrine in brain regions which receive noradrenergic innervation. Increased firing of the locus coeruleus is also associated with behavioral manifestations of fear, such as arched back and piloerection in the cat. Exposure to chronic stress results in long-term alterations in locus coeruleus firing and norepinephrine release in target brain regions of the locus coeruleus. Norepinephrine is also involved in neural mechanisms such as sensitization and fear conditioning, which are associated with stress. These findings are relevant to an understanding of psychiatric disorders, such as panic disorder and post-traumatic stress disorder (PTSD), the symptoms of which have been hypothesized to be related to alterations in noradrenergic function.
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Affiliation(s)
- J D Bremner
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
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Rowe JB, Saunders JR, Durantou F, Robbins TW. Systemic idazoxan impairs performance in a non-reversal shift test: implications for the role of the central noradrenergic systems in selective attention. J Psychopharmacol 1996; 10:188-94. [PMID: 22302944 DOI: 10.1177/026988119601000303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Two experiments examined the effect of pharmacological stimulation of the locus coeruleus in a non-reversal shift paradigm to test predictions concerning the role of the ceruleo-cortical noradrenergic system in processes of selective attention. Food-deprived rats were trained to make either visual (experiment 1) or spatial (experiment 2) discriminations in a parallel alley with both sets of cues being present at all times. Two groups of rats received treatments of either 2 mg/kg i.p. of the selective α(2) adrenoceptor antagonist idazoxan or saline control injections before each daily block of trials. Following attainment of criterion, the reinforcement contingencies were altered according to a non-reversal shift design, so that the alternative (i.e. either spatial or visual) set of cues now predicted reward. Rats treated with idazoxan were not impaired in the acquisition of either the spatial or visual discrimination task, but they were impaired in both forms of non-reversal shift. These deficits are interpreted as resulting from narrowed attention in idazoxan-treated rats, thus supporting a selective attention hypothesis of locus coeruleus function.
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Affiliation(s)
- J B Rowe
- Present address: Magdalen College, University of Oxford, Oxford OX1 4AU, UK
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Garcia C, Schmitt P, D'Aléo P, Bittel J, Curé M, Pujol JF. Regional specificity of the long-term variation of tyrosine hydroxylase protein in rat catecholaminergic cell groups after chronic heat exposure. J Neurochem 1994; 62:1172-81. [PMID: 7906716 DOI: 10.1046/j.1471-4159.1994.62031172.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The present study was carried out to investigate the effect of chronic heat exposure on tyrosine hydroxylase (TH) protein content in catecholaminergic rat brain-stem areas such as the anterior (LCA) and posterior (LCP) locus coeruleus, the substantia nigra (SN), the ventral tegmental area, and the dorsomedial (DMM) and the ventrolateral medulla and in the adrenal gland (AG). Male Sprague-Dawley rats were exposed to 34 degrees C during 3, 7, or 14 days. Controls were kept at 25 degrees C for the same period. In the LCA, TH content was decreased on day 7 (-34%) and 14 (-37%) of heat exposure. In the SN, TH protein content was decreased on day 7 (-25%) and 14 (-20%) after 34 degrees C. In the DMM cell group, 14 days at 34 degrees C produced a decrease (-20%) of TH content. In all of these structures, TH content variations were correlated with body temperature variations. In the AG, TH content increased progressively to peak (+31%) after 14 days of chronic heat exposure. This increase was also associated with body temperature modification. The selective and body temperature-related response to long-term TH protein content variations following chronic heat exposure observed in the LCA, SN, DMM, and AG could represent an adaptive physiological response of these catecholaminergic cells.
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Affiliation(s)
- C Garcia
- Laboratoire de Neuropharmacologie Moléculaire, CNRS-UMR 105, CERMEP, Lyon, France
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Sevcik J, Nieber K, Driessen B, Illes P. Effects of the central analgesic tramadol and its main metabolite, O-desmethyltramadol, on rat locus coeruleus neurones. Br J Pharmacol 1993; 110:169-76. [PMID: 8220877 PMCID: PMC2175982 DOI: 10.1111/j.1476-5381.1993.tb13788.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
1. Tramadol is a centrally acting analgesic with low opioid receptor affinity and, therefore, presumably additional mechanisms of analgesic action. Tramadol and its main metabolite O-desmethyltramadol were tested on rat central noradrenergic neurones of the nucleus locus coeruleus (LC), which are involved in the modulation of nociceptive afferent stimuli. 2. In pontine slices of the rat brain the spontaneous discharge of action potentials of LC cells was recorded extracellularly. (-)-Tramadol (0.1-100 microM), (+)-tramadol (0.1-100 microM), (-)-O-desmethyl-tramadol (0.1-100 microM) and (+)-O-desmethyltramadol (0.01-1 microM) inhibited the firing rate in a concentration-dependent manner. (+)-O-desmethyltramadol had the highest potency, while all other agonists were active at a similar range of concentrations. 3. (-)-Tramadol (10, 100 microM) was less inhibitory in brain slices of rats pretreated with reserpine (5 mg kg-1, 5 h before decapitation) than in controls. 4. The effect of (-)-tramadol (10 microM) was abolished in the presence of the alpha 2-adrenoceptor antagonist, rauwolscine (1 microM), whilst that of (+)-O-desmethyltramadol (0.3 microM) virtually disappeared in the presence of the opioid antagonist, naloxone (0.1 microM). (+)-Tramadol (30 microM) and (-)-O-desmethyl-tramadol (10 microM) became inactive only in the combined presence of naloxone (0.1 microM) and rauwolscine (1 microM). 5. In another series of experiments, the membrane potential of LC neurones was determined with intracellular microelectrodes. (-)-Tramadol (100 microM) inhibited the spontaneous firing and hyper-polarized the cells; this effect was abolished by rauwolscine (1 microM). (+)-O-desmethyltramadol (10 microM)had a similar but somewhat larger effect on the membrane potential than (-)-tramadol. The (+)-O-desmethyltramadol-(10 microM) induced hyperpolarization was abolished by naloxone (0.1 microM).6. The hyperpolarizing effect of noradrenaline (30 microM) was potentiated in the presence of (-)-tramadol(100 microM), but not in the presence of (+)-O-desmethyltramadol (10 microM). There was no potentiation of the noradrenaline (30 microM) effect, when the cells were hyperpolarized by current injection to an extent similar to that produced by (-)-tramadol (100 microM).7. Both noradrenaline (100 microM) and (- )-tramadol (100 microM) decreased the input resistance.8. The results confirm that the analgesic action of tramadol involves both opioid and non-opioid components. It appears that (-)-tramadol inhibits the uptake of noradrenaline and via a subsequent increase in the concentration of endogenous noradrenaline indirectly stimulates alpha2-adrenoceptors. (+)-0-desmethyltramadol seems to stimulate directly opioid micro-receptors. The effects of (+)-tramadol and(-)-O-desmethyltramadol consist of combined micro-opioid and alpha2-adrenergic components.
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Affiliation(s)
- J Sevcik
- Department of Pharmacology, University of Freiburg, Germany
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Olpe HR, Steinmann M. Responses of locus coeruleus neurons to neuropeptides. PROGRESS IN BRAIN RESEARCH 1991; 88:241-8. [PMID: 1813923 DOI: 10.1016/s0079-6123(08)63813-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The knowledge on the neuronal inputs to the locus coeruleus (LC) and their roles in regulating noradrenergic (NA) cellular activity is quite advanced. In recent years, however, about ten neuropeptides were found to be localized in the area of the rodent LC; peptides which may be considered as potential transmitters or modulators acting in this area. Electrophysiological studies performed in vivo and in vitro have revealed that many of these peptides are able to alter LC neuronal activity. Stimulatory effects have been described with vasopressin, substance P, adrenocorticotropin hormone and corticotropin-releasing factor. Depressant effects were seen with galanin, somatostatin, neuropeptide Y and enkephalin. Variable actions were observed in the case of neurotensin. While these findings point to a possible regulatory function of these peptides in this area, precise roles remain unclear. Important information is lacking that would conclusively demonstrate their regulatory functions. It should be determined whether the stimulation of peptidergic cells elicits synaptic effects identical to the ones observed with local exogenous peptide applications. By studying the action of blockers of these transmitter and modulator candidates, we would probably begin to understand their importance in the regulation of tonic and phasic activity components. The LC is generally considered to consist of a homogenous group of neurons. The recent observation that subpopulations of these cells contain peptides as in the case of neuropeptide Y, galanin and vasopressin, points to the possible existence of subgroups of neurons having different functions.
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Affiliation(s)
- H R Olpe
- Research and Development Department, CIBA-GEIGY Ltd., Basel, Switzerland
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Saiers JA, Campbell BA. Disruption of noradrenergic, but not serotonergic or opiate, functioning blocks both cardiac and behavioral components of the orienting response in preweanling rats. BEHAVIORAL AND NEURAL BIOLOGY 1990; 54:254-70. [PMID: 1964043 DOI: 10.1016/0163-1047(90)90628-j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Previous work in this laboratory established that selective attention, as measured by the behavioral and autonomic expressions of the orienting response (OR), is not disrupted by either dopaminergic or cholinergic receptor blockade. The present experiments extended this pharmacological analysis of the OR. In Experiment 1, preweanling rats were injected with methysergide maleate, a serotonin receptor blocker. Neither the behavioral nor the heart rate (HR) component of the OR was attenuated. In Experiment 2, the opiate receptor blocker naltrexone also failed to inhibit the HR and behavioral expressions of the OR. alpha-1 adrenergic receptor blockade with WB-4101 in Experiment 3 abolished both the HR and behavioral ORs to the pulsating tone. In Experiment 4, clonidine, which inhibits release of norepinephrine by stimulating alpha-2 autoreceptors, attenuated both behavioral and HR ORs to the pulsating tone in a dose-dependent manner. These data, in combination with the prior findings, suggest that norepinephrine is critically involved in the central process underlying the OR in the rat. Dopaminergic, cholinergic, serotonergic, and opiate receptor blockades do not impair selective attention as indexed by HR and behavioral ORs to an auditory stimulus. In contrast, disruption of noradrenergic functioning via either alpha-1 receptor blockade or alpha-2 receptor stimulation disrupts both the HR and behavioral components of the OR. These results indicate that integrity of central noradrenergic functioning is essential for expression of the OR and for stimulus-directed attention.
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Affiliation(s)
- J A Saiers
- Department of Psychology, Princeton University, New Jersey 08544-1010
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Gagne C, Moyse E, Kocher L, Bour H, Pujol JF. Light-microscopic localization of somatostatin binding sites in the locus coeruleus of the rat. Brain Res 1990; 530:196-204. [PMID: 1979928 DOI: 10.1016/0006-8993(90)91283-m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Somatostatin (SS14) binding sites within locus coeruleus (LC) were localized at the light microscope level by [125I][Tyr0,D-Trp8]SS14 radioautography combined with an immunohistochemical/neurotoxic lesioning approach. In intact rats, the dense accumulation of SS14 binding sites of LC conspicuously overlapped with the cluster of tyrosine hydroxylase (TH) immunoreactive neurons; SS14 specific binding was directly proportional to the number of TH immunostained (TH+) cell bodies per mg of tissue throughout LC. Complete lesion of catecholaminergic nerve cell bodies of LC by intracerebroventricular injection of 6-hydroxydopamine (6-OHDA) resulted in the total abolition of SS14 specific binding in the structure. In addition, specifically bound [125I][Tyr0, D-Trp8]SS14 and TH+ cell density were quantified serially in a set of rats bearing various partial neurotoxic lesions; a highly significant correlation was found between the two parameters at each of the 16 coronal levels of LC examined. The coefficient of proportionality was identical at all levels. These results strongly suggest that somatostatin binding sites are uniformly localized on all noradrenergic neurons of LC.
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Affiliation(s)
- C Gagne
- Laboratoire de Neuropharmacologie Moléculaire (UMR 105), CNRS, Faculté de Médecine A. Carrel, Lyon, France
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Fritschy JM, Grzanna R. Distribution of locus coeruleus axons within the rat brainstem demonstrated by Phaseolus vulgaris leucoagglutinin anterograde tracing in combination with dopamine-beta-hydroxylase immunofluorescence. J Comp Neurol 1990; 293:616-31. [PMID: 2329197 DOI: 10.1002/cne.902930407] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Projections of the locus coeruleus (LC) to the midbrain and hindbrain were analyzed by anterograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA-L). Following iontophoretic application of PHA-L into the LC, the distribution of labeled axons was analyzed in sections processed for the immunoperoxidase method and in sections processed for double-immunofluorescence staining using antibodies to PHA-L and to dopamine-beta-hydroxylase. This combined staining approach proved to be necessary for the unequivocal identification of LC axons in the brainstem since all injections labeled many non-noradrenergic axons whose distribution was different from that of LC fibers. The major new finding of the present study was the observation that large territories of the brainstem that receive a dense noradrenergic input are very sparsely innervated by the LC. Numerous labeled LC axons were observed in somatic afferent nuclei, tectum, pontine nuclei, interpenduncular nucleus, and inferior olivary complex. In contrast, very few labeled fibers were observed in autonomic and motor nuclei, and throughout the brainstem reticular formation, including raphe nuclei. Our data show that the distribution of LC axons in the brainstem is far less prominent than the projections of this nucleus to the forebrain and spinal cord. Our findings suggest that the dense NA projections to the core of the brainstem originate principally in non-LC NA neurons. On the basis of the present anatomical findings, a prominent role of the LC in motor and integrative functions of the brainstem appears unlikely.
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Affiliation(s)
- J M Fritschy
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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Chen MJ, Vigil A, Savage DD, Weiss GK. Transient elevation of amygdala alpha 2 adrenergic receptor binding sites during the early stages of amygdala kindling. Epilepsy Res 1990; 5:85-91. [PMID: 2158441 DOI: 10.1016/0920-1211(90)90023-o] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enhanced noradrenergic neurotransmission retards but does not prevent the development of kindling. We previously reported that locus coeruleus (LC) alpha 2 adrenergic receptor binding sites are transiently elevated during the early stages of kindling development. Since the firing activity of LC noradrenergic neurons is partially regulated via an alpha 2 receptor-mediated recurrent inhibition, the transient elevation in LC alpha 2 receptors could decrease LC activity and consequently facilitate the development of kindling. Transient elevation of alpha 2 receptor binding sites during early stages of kindling may also occur on noradrenergic axon terminals projecting to forebrain sites. Using in vitro neurotransmitter autoradiography techniques, we investigated this hypothesis by measuring specific [3H]idazoxan binding in 5 different areas of rat forebrain at 2 different stages of kindling development. After 2 class 1 kindled seizures, specific [3H]idazoxan binding was elevated significantly in the amygdala, but not in other forebrain regions. No differences in specific [3H]idazoxan binding were observed in any of the 5 brain regions in rats kindled to a single class 5 kindled motor seizure. Saturation of binding experiments indicated that the increase in amygdala [3H]idazoxan binding, following 2 class 1 kindled motor seizures, was due to an increase in the total number of alpha 2 receptor binding sites without a change in the affinity of the binding sites for [3H]idazoxan. Thus, the transient increase in alpha 2 receptors that occurs in the LC in the early stages of kindling also occurs in the forebrain region in which the kindled seizure originates.
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Affiliation(s)
- M J Chen
- Department of Pharmacology, University of New Mexico School of Medicine, Albuquerque 87131
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Justice A, Feldman SM, Brown LL. The nucleus locus coeruleus modulates local cerebral glucose utilization during noise stress in rats. Brain Res 1989; 490:73-84. [PMID: 2503233 DOI: 10.1016/0006-8993(89)90432-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Local cerebral glucose utilization (LCGU), estimated by the quantitative autoradiographic 2-deoxyglucose technique, was studied in rats with bilateral 6-hydroxydopamine lesions of the locus coeruleus (LC) and in vehicle-injected controls. Unanesthetized animals were studied during exposure to stressful levels of white noise (95 dB) or in relative silence (50 dB). Results indicated that noise caused greater and more widespread increases in LCGU in animals with LC lesions than in vehicle-injected controls. Lesions alone had little or no effect in animals not subjected to noise. Analyses of variance revealed significant treatment interaction effects (intact/lesion x silence/noise) for 37 of 109 regions measured. The pattern of results suggests that the LC acts during stress to limit unnecessary cerebral activity that might interfere with efficient sensory processing and/or the organization of appropriate behavioral responses. In this respect LC function may be similar to those actions of the peripheral sympathetic nervous system that suppress vegetative functions during stress to allow for the performance of coping responses.
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Affiliation(s)
- A Justice
- Department of Psychology, New York University, NY 10003
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Abstract
To understand the neurophysiological and neurochemical mechanisms of drug dependence, the functional significance of dopamine, noradrenaline and endogenous opioid peptides in the mediation of natural, self-stimulation and pharmacological reinforcement are discussed. Data on search of system(s), mediator(s) and neurons of reinforcement as well as my own notions on reinforcement as a critical element in organization and regulation of the organism's adaptive activity in variable environments are presented. The role of chronic drug-induced stable modification of central neurochemical systems' functioning as a basis for the alteration of endogenous reinforcement processes and raising drug dependence are examined in detail for main addictive drugs, opiates and psychomotor stimulants.
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Affiliation(s)
- E A Kiyatkin
- Department of Neuropharmacology, USSR Academy of Medical Sciences, Moscow
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Olpe HR, Steinmann MW, Pozza MF, Haas HL. Comparative investigations on the actions of ACTH1-24, somatostatin, neurotensin, substance P and vasopressin on locus coeruleus neuronal activity in vitro. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1987; 336:434-7. [PMID: 2448659 DOI: 10.1007/bf00164879] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A considerable number of neuropeptides have been localized immunohistochemically in the area of the locus coeruleus of the rat. The objective of this study was to assess the actions of some of these transmitter candidates on spontaneously active locus coeruleus neurons in vitro. The effects of bath-applied peptides on the discharge rate of individual locus coeruleus neurons were investigated. A midpontine slice preparation of the gerbil brain was used. Excitatory dose-dependent effects were found with four peptides with the following rank order of potency: Substance P, (Arg8)-vasopressin, neurotensin, ACTH1-24. Somatostatin hyperpolarized all neurons tested. Given the pronounced effects seen with substance P, somatostatin and vasopressin in the nanomolar range, it is conceivable that these peptides may have a role in regulating neuronal activity in locus coeruleus.
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Affiliation(s)
- H R Olpe
- Biology Research Laboratories, Ciba-Geigy Ltd., Basel, Switzerland
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Morilak DA, Fornal CA, Jacobs BL. Effects of physiological manipulations on locus coeruleus neuronal activity in freely moving cats. I. Thermoregulatory challenge. Brain Res 1987; 422:17-23. [PMID: 3676779 DOI: 10.1016/0006-8993(87)90535-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This and the following two papers examine the activity of locus coeruleus noradrenergic (LC-NE) neurons in response to a variety of physiological manipulations in unanesthetized, unrestrained cats. Unit responses were studied during a constant behavioral state in order to avoid the potentially confounding effects of state changes upon LC-NE unit discharge. In the present study, LC-NE unit activity was recorded during two thermoregulatory challenges: ambient heating and pyrogen-induced fever. These two conditions are particularly interesting since the direction of body temperature change that they produce is the same, but the thermoregulatory responses elicited are opposite, i.e. heat loss and heat gain. LC-NE neurons were activated by both manipulations. In response to ambient heating, neuronal activity increased only with the occurrence of panting, and not during earlier portions of the heating session. Following pyrogen administration, LC-NE neurons responded only during the peak increase in body temperature. Both of these effects on unit activity occurred independent of changes in behavioral state. Since both manipulations similarly increased LC-NE unit activity, despite eliciting opposite thermoregulatory responses, it appears that these neurons do not play a specific role in thermoregulation, but may participate in the response to physiological challenges in general.
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Affiliation(s)
- D A Morilak
- Department of Psychology, Princeton University, NJ 08544
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Morilak DA, Fornal CA, Jacobs BL. Effects of physiological manipulations on locus coeruleus neuronal activity in freely moving cats. III. Glucoregulatory challenge. Brain Res 1987; 422:32-9. [PMID: 3315119 DOI: 10.1016/0006-8993(87)90537-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Insulin-induced hypoglycemia and the subsequent administration of glucose were examined for their effects on single unit activity of locus coeruleus noradrenergic (LC-NE) neurons in unanesthetized, unrestrained cats. LC-NE neuronal activity showed an inverse relationship to blood glucose levels. The activity of most cells increased during sustained hypoglycemia, and then decreased following glucose administration. Some neurons were unaffected by hypoglycemia, but were inhibited following glucose. The activation of LC-NE neurons in response to insulin administration generally paralleled the increase in plasma epinephrine, although the adrenal response was more sensitive. These data, together with those reported in the preceding papers, suggest the following general conclusions: (1) physiological stimuli can influence the activity of LC-NE neurons in unanesthetized subjects (although they do so less strongly than environmental stimuli); (2) these effects of physiological stimuli upon LC-NE neurons can be exerted independent of changes in behavioral state; (3) LC-NE neurons do not appear to play a specific role in the regulation of any of the systems examined, but may instead play a more global role in the response to physiological challenges in general; (4) LC-NE neurons are generally co-activated with both the neural and hormonal components of the sympatho-adrenal system, although sympathetic activation can occur in the absence of increased LC-NE activity. A previously hypothesized role for LC-NE neurons in facilitating the behavioral response to environmental stressors may thus be extended to include the response to physiological challenges, and perhaps facilitation of the physiological as well as the behavioral components of the stress response.
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Affiliation(s)
- D A Morilak
- Department of Psychology, Princeton University, NJ 08544
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