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McMahon D, O'Reilly MA, Hynynen K. Therapeutic Agent Delivery Across the Blood-Brain Barrier Using Focused Ultrasound. Annu Rev Biomed Eng 2021; 23:89-113. [PMID: 33752471 DOI: 10.1146/annurev-bioeng-062117-121238] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Specialized features of vasculature in the central nervous system greatly limit therapeutic treatment options for many neuropathologies. Focused ultrasound, in combination with circulating microbubbles, can be used to transiently and noninvasively increase cerebrovascular permeability with a high level of spatial precision. For minutes to hours following sonication, drugs can be administered systemically to extravasate in the targeted brain regions and exert a therapeutic effect, after which permeability returns to baseline levels. With the wide range of therapeutic agents that can be delivered using this approach and the growing clinical need, focused ultrasound and microbubble (FUS+MB) exposure in the brain has entered human testing to assess safety. This review outlines the use of FUS+MB-mediated cerebrovascular permeability enhancement as a drug delivery technique, details several technical and biological considerations of this approach, summarizes results from the clinical trials conducted to date, and discusses the future direction of the field.
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Affiliation(s)
- Dallan McMahon
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada; .,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5, Canada
| | - Meaghan A O'Reilly
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada; .,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5, Canada
| | - Kullervo Hynynen
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada; .,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M4N 3M5, Canada
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Mondadori C. Pharmacological modulation of memory: trends and problems. ACTA NEUROLOGICA SCANDINAVICA. SUPPLEMENTUM 2009; 89:129-43. [PMID: 6120610 DOI: 10.1111/j.1600-0404.1981.tb02371.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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3
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Singer G. Brain behaviour relationships. AUSTRALIAN PSYCHOLOGIST 2007. [DOI: 10.1080/00050067608255692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- George Singer
- LaTrobe University
- Department of Psychology, La Trobe University, Bundoora, Vic., 3083
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Anaya-Martinez V, Martinez-Marcos A, Martinez-Fong D, Aceves J, Erlij D. Substantia nigra compacta neurons that innervate the reticular thalamic nucleus in the rat also project to striatum or globus pallidus: Implications for abnormal motor behavior. Neuroscience 2006; 143:477-86. [PMID: 17008017 DOI: 10.1016/j.neuroscience.2006.08.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 08/04/2006] [Accepted: 08/08/2006] [Indexed: 10/24/2022]
Abstract
The projections of the substantia nigra pars compacta (SNc) to the reticular thalamic nucleus (RTn) were assessed by measuring dopamine content and counting tyrosine hydroxylase positive (TH (+)) cells in rats with unilateral lesions induced by 6-hydroxydopamine (6-OHDA), and by using a fluorescent tract-tracing technique in rats without lesions. Injection of 6-OHDA in the RTn reduced dopamine content and the number of TH (+) cells in the SNc by about 50%. Branching of SNc was suggested by the finding that 6-OHDA deposited in the RTn significantly reduced dopamine in the striatum and globus pallidus. Moreover, injections of 6-OHDA into either the striatum or the globus pallidus significantly reduced dopamine content in the RTn. Fluorescent tracers injected into the RTn labeled TH (+) cells in the SNc. A high proportion of these TH (+) cells was double labeled when tracers were also injected into either the globus pallidus or striatum. Other experiments showed that systemic injection of apomorphine or methamphetamine induced turning behavior in rats with local deposits of 6-OHDA in either the RTn or the studied basal ganglia nuclei. The extensive dopaminergic branching suggests that the abnormal motor behavior of rats with 6-OHDA deposits in the RTn may be caused by dopaminergic denervation of more than one structure. The fact that lesion of a single dopaminergic neuron can reduce dopamine transmission in more than one structure is probably important in generating the manifestations of Parkinson's disease.
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Affiliation(s)
- V Anaya-Martinez
- Departamento de Fisiología, Biofísica y Neurociencias, Cinvestav, Apartado postal 14-740, México D.F., 07000 Mexico
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Höcht C, Opezzo JAW, Taira CA. Applicability of reverse microdialysis in pharmacological and toxicological studies. J Pharmacol Toxicol Methods 2006; 55:3-15. [PMID: 16567112 DOI: 10.1016/j.vascn.2006.02.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 02/15/2006] [Indexed: 10/24/2022]
Abstract
A recent application of microdialysis is the introduction of a substance into the extracellular space via the microdialysis probe. The inclusion of a higher amount of a drug in the perfusate allows the drug to diffuse through the microdialysis membrane to the tissue. This technique, actually called as reverse microdialysis, not only allows the local administration of a substance but also permits the simultaneous sampling of the extracellular levels of endogenous compounds. Local effects of exogenous compounds have been studied in the central nervous system, hepatic tissue, dermis, heart and corpora luteae of experimental animals by means of reverse microdialysis. In central nervous studies, reverse microdialysis has been extensively used for the study of the effects on neurotransmission at different central nuclei of diverse pharmacological and toxicological agents, such as antidepressants, antipsychotics, antiparkinsonians, hallucinogens, drugs of abuse and experimental drugs. In the clinical setting, reverse microdialysis has been used for the study of local effects of drugs in the adipose tissue, skeletal muscle and dermis. The aim of this review is to describe the principles of the reverse microdialysis, to compare the technique with other available methods and finally to describe the applicability of reverse microdialysis in the study of drugs properties both in basic and clinical research.
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Affiliation(s)
- Christian Höcht
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina.
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Kasamatsu T, Schmidt EK. Continuous and direct infusion of drug solutions in the brain of awake animals: implementation, strengths and pitfalls. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 1997; 1:57-69. [PMID: 9385048 DOI: 10.1016/s1385-299x(96)00008-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
One of the best strategies for understanding an animal's behavior is to study the function of the brain by experimentally modifying brain chemistry temporarily or on a long-term basis. This can be achieved by direct manipulation of neurochemistry of a targeted brain area with various drugs whose in vitro specificity and sensitivity are known. We assume that an animal's behavior is primarily controlled by the integrated performance of neural networks, rather than the action of a "superstar" single neuron which has narrowly tuned selectivity, in a specified brain region. Therefore, the former must be regulated by a large number of combinations of various transmitter/modulator receptors, hormones, growth factors, and other biochemically identifiable and yet unidentified substances. Under certain conditions, the activation of receptor-bound second messenger systems is thought to cause the enhanced expression of particular genes. Given the wide possibilities in manipulating brain chemistry, which may otherwise result in a variety of consequences, it is crucial to have a dependable means of sustaining the steady-state action of a drug for a sufficiently long time period at a targeted area in the brain of behaving animals. In most cases the continuous application of a drug is necessary to counteract its secondary mitigating effect, which is set in action through negative feedback loops and which in effect reduces the primary action of the drug in use. We have developed a technique to answer this need, using the Alzet osmotic minipump as the source of the continuous infusion force. A drug solution is continuously and directly infused, guided through a chronically implanted cannula, into a targeted area in the brain of behaving animals. The consequences of such an infusion are assessed, during as well as after the infusion, using various types of measurements in behavior, biochemistry, neurophysiology, pharmacology and morphology. The method has been successfully applied, for example, to the study of developmentally regulated neural plasticity in cat visual cortex. A few preconditions should be satisfied for the method to be properly applied to the brains of live animals. Those are: (1) manufacturing a suitable guide system, i.e., cannula-minipump assembly, for the infusion solution; (2) stereotaxic implantation of a cannula-minipump assembly into a selected brain region; and (3) estimating the concentration gradient of the continuously infused solution. This is crucial to assess the specificity and sensitivity of a drug for its assumed effects in vivo.
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Affiliation(s)
- T Kasamatsu
- Smith-Kettlewell Eye Research Institute, San Francisco, CA 94115, USA
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Simpson CW, Ruwe WD, Myers RD. Prostaglandins and hypothalamic neurotransmitter receptors involved in hyperthermia: a critical evaluation. Neurosci Biobehav Rev 1994; 18:1-20. [PMID: 7909592 DOI: 10.1016/0149-7634(94)90033-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The role of a prostaglandin of the E series (PGE) in the hypothalamic mechanisms underlying a fever continues to be controversial. This paper reviews the historical literature and current findings on the central action of the PGEs on body temperature (Tb). New experiments were undertaken to examine the local effect of muscarinic, nicotinic, serotonergic, alpha-adrenergic, or beta-adrenergic receptor antagonists at hypothalamic sites where PGE1 caused a rise in Tb of the primate. Guide tubes for microinjection were implanted stereotaxically above sites in and around the anterior hypothalamic, preoptic area (AH/POA) of male Macaque monkeys. Following postoperative recovery, 30-100 ng of PGE1 was micro-injected unilaterally in a volume of 1.0-1.5 microliter at sites in the AH/POA to evoke a rise in Tb, and once identified, pretreated with a receptor antagonist. PGE1 hyperthermia was significantly reduced by microinjections of the muscarinic and nicotinic antagonists, atropine, or mecamylamine, at PGE1 reactive sites in the AH/POA. The serotonergic antagonist, methysergide, injected at PGE1 sensitive sites in the ventromedial hypothalamus also attenuated the rise in Tb. However, the 5-HT reuptake blocker, fluoxetine, and the beta-adrenergic receptor antagonist, propranolol, injected in the AH/POA failed to alter the PGE1 hyperthermia. In contrast, the alpha-adrenergic antagonist, phentolamine, potentiated the increase in Tb at all PGE1 reactive sites in the hypothalamus. An updated model is presented to explain how the concurrent actions of aminergic neurotransmitters acting on their respective receptors in the hypothalamus can interact with a PGE to elicit hyperthermia. Finally, an evaluation of the current literature including recent findings on macrophage inflammatory protein (MIP-1) supports the conclusion that a PGE in the brain is neither an obligatory nor essential factor for the expression of a pyrogen fever.
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Affiliation(s)
- C W Simpson
- Division of Molecular Biology and Biochemistry, University of Missouri, Kansas City 64108
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Bazzett TJ, Becker JB, Albin RL. A novel device for chronic intracranial drug delivery via microdialysis. J Neurosci Methods 1991; 40:1-8. [PMID: 1839046 DOI: 10.1016/0165-0270(91)90111-c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A system is described for chronic intracranial drug administration in the rat using a modified in vivo microdialysis probe coupled to an Alzet model 2002 osmotic minipump. The results presented demonstrate that this system can be used for the chronic administration of quinolinic acid with minimal non-specific damage. Each pump delivered approximately 225 microliters of solution over a period of 19-20 days when tested in vitro. The dialysis units were uniform in function, delivering greater than 93% of the [3H]quinolinic acid initially loaded into the minipump. For in vivo analysis of this apparatus the dose of quinolinic acid tested produced extensive destruction of the striatum. The present system allows reliable drug diffusion over a relatively large area without pressure injection variability. In conclusion, we have developed a simple and inexpensive technique for administration of drugs into brain parenchyma with substantial advantages over previously used techniques.
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Affiliation(s)
- T J Bazzett
- Department of Psychology, University of Michigan, Ann Arbor 48104-1687
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Dubach M. Distribution of intracerebrally injected dopamine as studied by a punch-scintillation modeling technique. Neuroscience 1991; 45:103-15. [PMID: 1754060 DOI: 10.1016/0306-4522(91)90107-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Three-dimensional distribution gradients of intracerebrally injected tritiated dopamine were calculated on the basis of concentrations in multiple punch-samples from sequential sections of Macaca fascicularis brain tissue. The monkey was pretreated systemically with a monoamine oxidase inhibitor to retard elimination. Gradients were best fit by cubic exponential equations relating concentration to distance from the center of the site. The concentration at the center, total amount of label, and total extent of the site injected just before perfusion were consistent with initial distribution in the extracellular space, if the volume fraction of the latter is estimated at 20%. The extent of distribution was distinctly greater in the mediolateral and dorsoventral dimensions than in the anteroposterior dimension. The total amount of label near the site decreased rapidly in the first few minutes after injection, then much more slowly, reaching about 30% of the injected amount after 2 h. Its distribution within the site changed steadily, the outer boundary gradually expanding and the peak at the center gradually decreasing. This pattern was consistent with an initial rapid dispersion by injection pressure and an initial loss of tritiated dopamine due to disruption of the blood-brain barrier at the center of the site, followed by a steady expansion of the site driven by diffusion and bulk flow.
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Affiliation(s)
- M Dubach
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle 98195
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Willis GL, Smith GC. The amine accumulation-producing capacity of 6-hydroxydopamine and its neurochemical specificity. Brain Res Bull 1986; 17:145-9. [PMID: 3094834 DOI: 10.1016/0361-9230(86)90109-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
There was considerable research during the 1970's addressing the problem of the neurospecificity of 6-hydroxydopamine (6-OHDA). Despite the numerous attempts to define the criteria governing the use of this drug in experimental paradigms, some believed that specific damage to catecholamine (CA)-containing neurones could be achieved only by controlling the dose injected, while others claimed that the neurotoxic effect that this drug had on non-CA systems was so severe that it contraindicated its use experimentally. The issue still remains unresolved. In the present study, we examined the degree of neurochemical specificity produced by 6-OHDA or radiofrequency (RF) lesions by comparing the quantity of amine accumulation to the amount of physical damage at the lesion site (termed non-specific damage, NSD) which each technique produced. The volume of NSD produced by 6-OHDA (2 microliter of 8 micrograms/ul) was significantly less than that produced by large RF lesions (60 degrees C for 50 sec) both of which has a similar effect on the regulation of short term body weight. Both types of lesions produced similar quantities of amine accumulation. Smaller RF lesions (45 degrees C for 30 sec) produced the same amount of NSD as did 6-OHDA but significantly less amine accumulation and had no effect on body weight regulation. The ratio of NSD to amine accumulation in 6-OHDA treated rats was 3/1 while large and small RF lesions produced a NSD/accumulation ratio of 15/1. The present results reveal that the neurochemical specificity of 6-OHDA is several magnitudes greater than with RF lesions, when using the criteria as defined in the present experiment.(ABSTRACT TRUNCATED AT 250 WORDS)
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11
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Burnstock G. Morphological changes produced by drugs acting on the autonomic nervous system. PHARMACOLOGY & THERAPEUTICS. PART B: GENERAL & SYSTEMATIC PHARMACOLOGY 1979; 5:49-53. [PMID: 386378 DOI: 10.1016/0163-7258(79)90073-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Reyes Vazquez C, Zarco-Coronado I, Brust-Carmona H. Effects of intracaudate microinjections of 6-hydroxydopamine upon the suppression of lever pressing and upon passive avoidance conditioning in cats. Pharmacol Biochem Behav 1978; 9:747-51. [PMID: 746050 DOI: 10.1016/0091-3057(78)90351-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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13
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Myers RD, Hoch DB. 14C-dopamine microinjected into the brain-stem of the rat: dispersion kinetics, site content and functional dose. Brain Res Bull 1978; 3:601-9. [PMID: 318183 DOI: 10.1016/0361-9230(78)90006-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A morphological analysis was undertaken of both the dispersion characteristics and tissue content of dopamine (DA) microinjected acutely into the brain-stem of the anesthetized rat. 14C-DA, with a specific activity of 56-62 mCi/mMol, was infused unilaterally into the pars compacta of the substantia nigra in one of four test volumes: 0.5, 1.0, 4.0 or 8.0 microliters. The concentration of the 14C-DA solution was 1.0 microCi/microliter, equivalent to 3.01 micrograms/microliters, which was delivered at an injection rate of 1.0 microliter per 45 sec. At an interval of either one min or 15 min following the microinjection, the rat's brain was removed rapidly from its calvarium, flash frozen and then cut in the coronal plane on a freezing microtome in 500 micron slabs. After each of the respective serial slabs was mounted on glass, the Eik Nes-Brizzee trochar technique for the discrete removal of tissue samples was used to obtain 0.5 mm dia. cylindrical plugs of meso-diencephalic tissue at distances from the site of injection ranging from 0.5 to 2.5 mm, center to center. Each sample plug was subsequently solubilized and 14C-DA activity quantitated by liquid scintillation spectrometry. The results show that regardless of volume, the spatial patterning of the microinjected solution assumes a tear-drop or pear shape, not a sphere. Further, as the volume of the injection is increased from 0.5 to 8.0 microliters, the magnitude of the dispersion of 14C-DA is enhanced throughout the surrounding parenchyma, but not in a linear fashion.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R D Myers
- Department of Psychiatry, University of North Carolina, School of Medicine, Chapel Hill 27514
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Da Prada M, Pieri L, Keller HH, Pieri M, Bonetti EP. Effects of 5,6-dihydroxytryptamine and 5,7-dihydroxytryptamine on the rat central nervous system after intraventricular or intracerebral application and on blood platelets in vitro. Ann N Y Acad Sci 1978; 305:595-620. [PMID: 152083 DOI: 10.1111/j.1749-6632.1978.tb31551.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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PROCEEDINGS OF THE AUSTRALASIAN SOCIETY OF CLINICAL AND EXPERIMENTAL PHARMACOLOGISTS. Clin Exp Pharmacol Physiol 1978. [DOI: 10.1111/j.1440-1681.1978.tb00677.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Myers RD, Ruwe WD. Thermoregulation in the rat: deficits following 6-OHDA injections in the hypothalamus. Pharmacol Biochem Behav 1978; 8:377-85. [PMID: 674250 DOI: 10.1016/0091-3057(78)90073-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bilateral microinjections of 6-hydroxydopamine (6-OHDA) were made in a volume of 0.5--0.75 microliter through chronically implanted cannulae into anterior hypothalamic, preoptic loci. Sites were selected at which 1.0 to 12.5 microgram of norepinephrine (NE) had previously elicited a fall in the rat's body temperature. After 2.0 to 6.0 microgram of 6-OHDA were injected in the same volume at the same loci, a comparable hypothermia ensued. When the rats were exposed repeatedly for one-hour intervals to an environmental temperature of either 35.0 degrees C or 8.0 degrees C, they were unable to thermoregulate against the heat and their colonic temperature rose. In some experiments, the rats also failed to defend adequately against the cold ambient temperature, but mainly following the microinjection of the higher doses of 6-OHDA . The intakes of food and water were generally suppressed; this was accompanied by a transient decline in body weight. Overall, the severity, duration and direction of the thermoregulatory impairment depended upon the anatomical site of injection and the dose regimen of the neurotoxin employed. These results offer further evidence that an intact catecholaminergic pathway within the anterior hypothalamus is required for the rat's physiological control of heat loss in a warm environmental temperature.
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Mason ST, Iversen SD. An investigation of the role of cortical and cerebellar noradrenaline in associative motor learning in the rat. Brain Res 1977; 134:513-27. [PMID: 332274 DOI: 10.1016/0006-8993(77)90826-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Abstract
Lesion to the fibres of the dorsal noradrenergic bundle arising from the locus coeruleus using the selective neurotoxin 6-hydroxydopamine has been shown to produce a resistance to extinction on a number of behavioural tests without affecting the acquisition learning process itself. The experiments reported here are aimed at elucidating the behavioural mechanisms involved in this resistance to extinction. Theories invoking general hyperactivity, internal inhibition and perseveration are tested in the following experiments and all are shown to be contrary to the observed facts. On the basis of other data it is tentatively concluded that the dorsal noradrenergic bundle may play a role in the filtering out of irrelevant stimuli or in the memory of non-reward.
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Oltmans GA, Lorden JF, Margules DL. Food intake and body weight: effects of specific and non-specific lesions in the midbrain path of the ascending noradrenergic neurons of the rat. Brain Res 1977; 128:293-308. [PMID: 871916 DOI: 10.1016/0006-8993(77)90996-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bilateral injections of 4.8 or 12 microgram of 6-hydroxydopamine hydrobromide were made in the midbrain path of the ascending norepinephrine (NE) fibers. Maximum NE depletion was obtained with the 4 microgram dose. Increasing the dose did not increase NE depletion in either the hypothalamus or the telencephalon. Increases in food intake were observed following the 12 microgram dose only. Electrolytic, copper sulfate, or 5,6-dihydroxytryptamine lesions at the same site caused increases in both food intake and body weight with only moderate (-32 to -58%) decreases in NE levels. Behavioral changes were seen in only those groups in which a large amount of non-specific tissue damage was also observed. Therefore, the behavioral effects were attributed to general tissue damage in the area and not the NE fibers specifically.
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Lorez HP. Catecholamine fluorescence in the brains of chemically sympathectomized adult rats: increased fluorescence in bulbospinal neurons. Brain Res 1977; 128:361-8. [PMID: 326351 DOI: 10.1016/0006-8993(77)91002-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Singer G, Armstrong S. Effects of intracranial injections of 6-OHDA on food and water intakes, body temperature and body weight regulation in the rat. Pharmacol Biochem Behav 1976; 5:309-17. [PMID: 996064 DOI: 10.1016/0091-3057(76)90083-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
6-Hydroxydopamine was injected either intraventricularly (320 mug in 10 mul) or intrahypothalamically (64 mug in 2 mul) into rats kept under either free feeding or body weight reduced conditions. Intraventricular injections caused a temporary aphagia and hypodipsia in free feeding rats but daily measurements failed to reveal any long term effects; body weight reduced rats did not display the temporary aphagia but were initially hyperphagic. Injections into the more rostral hypothalamic areas of free feeding rats also showed only minimal short term effects; however, some of the body weight in both body weight reduced group died within several days of injection. Injections made at more posterior loci again showed very little effect in both body weight reduced and free feeding groups; some temporary disruption of feeding occurred from lesions in the proximity of the zone incerta of some free feeding animals.
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Willis GL, Singer G, Evans BK. Intracranial injections of 6-OHDA. Comparison of catecholamine-depleting effects of different volumes and concentrations. Pharmacol Biochem Behav 1976; 5:207-13. [PMID: 996052 DOI: 10.1016/0091-3057(76)90038-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Fluorescence histochemistry was used to assess monoamine depletion after injections of 6-OHDA into selected brain areas. Two volumes (2 and 4 mul) and 4 concentrations (1, 2, 4 and 8 mug/mul) of 6-OHDA were injected into the olfactory tubercle, the posterior lateral hypothalamus and the lateral hyopthalamus. Selective destruction of catecholamine-containing neurons resulted from all injections of 6-OHDA with the exception of the 2 lowest doses (2 and 4 mul of 1 mug/mul) and the highest dose (4 mul of 8 mug/mul) which produced nonspecific damage of brain parenchyma. The results indicate that, in addition to the selection of an effective dose, it is also possible to choose a site of injection which will produce a maximal area of specific depletion. In cases where injections into terminal areas caused limited specific depletion the same dose injected into preterminal axons often caused a more widespread loss of fluorescence. With volume, concentration and anatomical location being important variables to consider, caution is needed in the interpretation of behavioural experiments. When using 6-OHDA it is necessary to show that specific depletion of catecholamines has been achieved.
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Abstract
NGF is a protein that stimulates growth and differentiation of sympathetic and sensory components of the peripheral nervous system. The purpose of this review is to examine the evidence that NGF has similar activity in the central nervous system. First, the primary mode of interaction of NGF with the nerve cell will be discussed, and the possibility that such an interaction takes place in the brain will be examined. Recent studies have demonstrated that NGF promotes regenerative sprouting of damaged catecholamine-containing neurons in the brain. The next part of the paper reviews this literature, and other findings that indicate or contraindicate a role of NGF in brain maturation of maintenance. The final part of this paper suggests specific avenues for future research in this area, and presents conclusions regarding the literatureon brain activity of NGF to date.
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Evans BK, Singer G, Armstrong S, Saunders PE, Burnstock G. Effects of chronic intracranial injection of low and high concentrations of guanethidine in the rat. Pharmacol Biochem Behav 1975; 3:219-28. [PMID: 1096174 DOI: 10.1016/0091-3057(75)90151-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Low (64 mug in 2 mul) or high 320-1280 mug in 2 mul) doses of guanethidine sulphate were injected daily for up to 19 days into the lateral hypothalamus, substantia nigra, locus coeruleus, dorsal raphe nucleus, or amygdala region of the rat brain. Effects on monoamine-containing neurons were determined using fluorescence histochemistry. The noradrenergic terminals of the hypothalamus were depleted over a diameter of 7 mm by both low and high doses of guanethidine whereas, even with high doses, the dopaminergic terminals of the median eminence, amygdala and acudate nucleus were only partially depleted. Fluorescence levels of dopaminergic cell bodies of the sub stantis nigra and 5HT-containing cell bodies of the dorsal raphe nucleus were unaltered by low doses of guanethidine. Low doses of guanethidine did not affect the fluorescence of the noradrenergic cell bodies of the locus coeruleus, however high doses caused a substantial reduction in fluorescence levels. Normal levels of fluorescence were observed in all catecholamine-containing neurons within 14 days from cessation of injections. Thus, the xon retraction and eventual degeneration of peripheral sympathetic adrenergic neurons, which occurs as a result of chronic intraperitoneal injections of guanethidine does not occur with the catecholamine-containing neurons in the central nervous system. The rapid recovery of centrat catecholamine-containing neurons is remarkable in view of the extensive areas of brain damage produced by chronic injection of such high concentrations of drug. Fluorescence in peripheral adrenergic nerves was unaffected by chronic injection of guanethidine into the lateral hypothalamus but adhesions of some internal organs were observed. Blood vessels in the vicinity of the cannula were heavily reinnervated by fluorescent fibres probably arising from intracranial catecholamine-containing neurons. Some of the advantages of intracranial injection of guanethidine compared to 6-hydroxydopamine for behavioral experiments are discussed.
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