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Pharmacological approaches to habituation of the acoustic startle response in rats. ACTA ACUST UNITED AC 2013. [DOI: 10.3758/bf03335322] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
One of the oldest models of schizophrenia is based on the effects of serotonergic hallucinogens such as mescaline, psilocybin, and (+)-lysergic acid diethylamide (LSD), which act through the serotonin 5-HT(2A) receptor. These compounds produce a 'model psychosis' in normal individuals that resembles at least some of the positive symptoms of schizophrenia. Based on these similarities, and because evidence has emerged that the serotonergic system plays a role in the pathogenesis of schizophrenia in some patients, animal models relevant to schizophrenia have been developed based on hallucinogen effects. Here we review the behavioural effects of hallucinogens in four of those models, the receptor and neurochemical mechanisms for the effects and their translational relevance. Despite the difficulty of modelling hallucinogen effects in nonverbal species, animal models of schizophrenia based on hallucinogens have yielded important insights into the linkage between 5-HT and schizophrenia and have helped to identify receptor targets and interactions that could be exploited in the development of new therapeutic agents.
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Mendelson SD. A review and reevaluation of the role of serotonin in the modulation of lordosis behavior in the female rat. Neurosci Biobehav Rev 1992; 16:309-50. [PMID: 1528523 DOI: 10.1016/s0149-7634(05)80204-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The role of serotonin (5-HT) in the modulation of sexual receptivity (lordosis) in the female rat is reviewed and reevaluated. The effects on lordosis of drug treatments that decrease or increase the activity and availability of central 5-HT are first discussed, and this is followed by an evaluation of the effects of drugs that act directly at 5-HT receptors. In order to shed light on the physiological significance of effects of serotonergic drugs on lordosis, there is also a review of what is known of changes in levels of serotonergic activity and densities of 5-HT receptors in the female rat brain that take place through the estrous cycle and in response to administration of behaviorally effective doses of gonadal steroids. Serotonin has generally been thought to have a tonic, inhibitory effect on lordosis. However, it is concluded that 5-HT can either inhibit or facilitate lordosis depending on which subtypes of central 5-HT receptors become activated. Because of a lack of consistent or compelling evidence of effects of ovarian hormones on serotonergic activity or 5-HT receptors in critical areas of the brain, it is stated that there is at present no basis to conclude that the effects of pharmacological manipulations of serotonergic activity on lordosis reflect an important, physiological role of 5-HT in the modulation of lordosis behavior in the female rat.
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Affiliation(s)
- S D Mendelson
- Laboratory of Neuroendocrinology, Rockefeller University, New York, NY 10021
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Deliganis AV, Pierce PA, Peroutka SJ. Differential interactions of dimethyltryptamine (DMT) with 5-HT1A and 5-HT2 receptors. Biochem Pharmacol 1991; 41:1739-44. [PMID: 1828347 DOI: 10.1016/0006-2952(91)90178-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The interactions of the indolealkylamine N,N-dimethyltryptamine (DMT) with 5-hydroxytryptamine1A (5-HT1A) and 5-HT2 receptors in rat brain were analyzed using radioligand binding techniques and biochemical functional assays. The affinity of DMT for 5-HT1A sites labeled by [3H]-8-hydroxy-2-(di-n-propylamino)tetralin ([3H]-8-OH-DPAT) was decreased in the presence of 10(-4) M GTP, suggesting agonist activity of DMT at this receptor. Adenylate cyclase studies in rat hippocampi showed that DMT inhibited forskolin-stimulated cyclase activity, a 5-HT1A agonist effect. DMT displayed full agonist activity with an EC50 of 4 x 10(-6) M in the cyclase assay. In contrast to the agonist actions of DMT at 5-HT1A receptors, DMT appeared to have antagonistic properties at 5-HT2 receptors. The ability of DMT to compete for [3H]-ketanserin-labeled 5-HT2 receptors was not affected by the presence of 10(-4) M GTP, suggesting antagonist activity of DMT at 5-HT2 receptors. In addition, DMT antagonized 5-HT2-receptor-mediated phosphatidylinositol (PI) turnover in rat cortex at concentrations above 10(-7) M, with 70% of the 5-HT-induced PI response inhibited at 10(-4) M DMT. Micromolar concentrations of DMT produced a slight PI stimulation that was not blocked by the 5-HT2 antagonist ketanserin. These studies suggest that DMT has opposing actions on 5-HT receptor subtypes, displaying agonist activity at 5-HT1A receptors and antagonist activity at 5-HT2 receptors.
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Affiliation(s)
- A V Deliganis
- Neurology Service (127), VA Medical Center, Palo Alto, CA 94304
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Davis M. Mescaline: excitatory effects on acoustic startle are blocked by serotonin2 antagonists. Psychopharmacology (Berl) 1987; 93:286-91. [PMID: 3124159 DOI: 10.1007/bf00187244] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The ability of serotonin2 (5-HT2) antagonists to block the excitatory effects of mescaline on the acoustic startle reflex were analyzed. Mescaline (20 mg/kg) caused a consistent increase in the amplitude of the acoustic startle reflex. This effect was blocked in a dose-related fashion by the 5-HT2 antagonist ritanserin (ED50 dose = 0.25 mg/kg IP). In contrast, even a high dose of ritanserin (2.0 mg/kg) did not block the excitatory effects of amphetamine on startle. Other 5-HT2 antagonists (ketanserin, cinanserin, LY 53857) also blocked mescaline's effect, whereas the 5-HT1 antagonist pindolol (5 mg/kg) did not. These results support the hypothesis that the behavioral effects of hallucinogens are mediated by agonist actions at 5-HT2 receptors.
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Affiliation(s)
- M Davis
- Department of Psychiatry, Yale University, New Haven, CT 06508
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Rasmussen K, Aghajanian GK. Effect of hallucinogens on spontaneous and sensory-evoked locus coeruleus unit activity in the rat: reversal by selective 5-HT2 antagonists. Brain Res 1986; 385:395-400. [PMID: 3096493 DOI: 10.1016/0006-8993(86)91090-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
As previously reported, systemic administration of the hallucinogens D-lysergic acid diethylamide (LSD) (5-10 micrograms/kg) and mescaline (2 mg/kg) in the anesthetized rat produced a decrease in spontaneous activity but, paradoxically, facilitated activation of locus coeruleus (LC) neurons by sciatic nerve stimulation. In the present study, the hallucinogen 2,5-dimethoxy-4-methylamphetamine (DOM) (20-80 micrograms/kg) was found to have similar effects. Systemic administration of the selective 5-HT2 antagonists LY 53857 (0.02-0.8 mg/kg) and ritanserin (0.1-0.3 mg/kg) completely reversed both actions of the hallucinogens on the LC. In contrast, LY 53857 did not reverse the effects of (+)-amphetamine (0.5 mg/kg) on the spontaneous or sensory-evoked activity of the LC. These results suggest that the common actions of indoleamine and phenethylamine hallucinogens displayed in the LC are mediated via 5-HT2 receptors; however, these receptors appear to be located outside the LC itself.
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Eison AS, Eison MS, Stanley M, Riblet LA. Serotonergic mechanisms in the behavioral effects of buspirone and gepirone. Pharmacol Biochem Behav 1986; 24:701-7. [PMID: 2871564 DOI: 10.1016/0091-3057(86)90577-0] [Citation(s) in RCA: 174] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The literature describing the role of serotonin (5-HT) in the mediation of anxiety is a controversial one. Serotonergic involvement in the mechanism of action of two nonbenzodiazepine anxiolytics, buspirone and gepirone, supports a role for serotonin in anxiety. The anticonflict effect of both drugs is blocked by serotonin lesions, and gepirone induces the serotonin syndrome. A shift in the gepirone dose-response curve to the left in serotonin lesioned rats suggests that this may be 5-HT-receptor mediated. Both buspirone and gepirone enhance the acoustic startle response and gepirone's effect is attenuated in serotonin lesioned animals. While other components of buspirone's mechanism of action may suppress the behavioral expression of its serotonergic interactions, results from these studies suggest that serotonin agonist-like activity may be an important mechanism in the actions of a clinically proven nonbenzodiazepine anxiolytic (buspirone), and anxiolytic candidate (gepirone).
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Abstract
Research is reviewed arising from the proposition that behavioral habituation is mediated by brain mechanisms operated by the neurotransmitter, acetylcholine. Effects of cholinergic drugs on habituation of the startle response in rats fail to support involvement of acetylcholine. Likewise, serotonergic drug effects do not favor the more recent view that startle habituation depends on brain serotonin, nor is there sufficient evidence for an essential role of either dopamine or noradrenaline . Because of persistence of habituation following challenge with a variety of pharmacological agents, the phenomenon probably depends upon a complex interplay between a number of transmitters and behavioral processes. Contrary to earlier belief, no single transmitter should be seen as crucially responsible for startle habituation.
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Pellet J, Weiss M, Gourdon MJ. Harmaline effects on the sensory-motor reactivity: modifications of the acoustic startle pattern. Pharmacol Biochem Behav 1983; 19:527-34. [PMID: 6634903 DOI: 10.1016/0091-3057(83)90130-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effects of harmaline, an indoleamine and a MAOI, were tested on the acoustic startle pattern. EMG measures of the startle reflex, the pinna reflex as well as the characters of the vertex evoked responses to brief intense tone bursts (60 msec, 110 dB, 8000 Hz) were simultaneously studied in 4 alert guinea-pigs. The basic experimental design was a 4 by 4 latin square, with the treatments being given at 2 day intervals. The four harmaline-HCl treatments were isotonic saline, 0.25, 5.0, and 10.0 mg/kg. Compared with saline baselines, all the doses resulted, throughout the 60 min session, in overall high significant depressions of the startle reflex, the pinna reflex and the initial wave of the acoustic evoked potential at the vertex. In contrast, harmaline had little or no influence on amplitude and latency of the late wave of the vertex response. The effects of harmaline on the general behavior of the guinea-pig are also reported. These results may support an involvement of serotonergic systems in the modulation of the sensory-motor reactivity at the brainstem level. Nevertheless, the probably more complex cortical processes involved in startle responsiveness do not appear univocally affected by the indoleamine drugs such as harmaline.
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Appel JB, White FJ, Holohean AM. Analyzing mechanism(s) of hallucinogenic drug action with drug discrimination procedures. Neurosci Biobehav Rev 1982; 6:529-36. [PMID: 7177512 DOI: 10.1016/0149-7634(82)90036-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Some of the advantages of using drug discrimination (DD) procedure to analyze the mechanisms of action of hallucinogenic and related drugs were illustrated by reviewing research with lysergic acid diethylamide (LSD). Because they ensure that drug-induced alterations in interoceptive "state" become biologically meaningful "cues," these procedures are reliable, robust, sensitive and specific. With reference to LSD, many DD experiments suggest: (1) that while hallucinogens substitute for (mimic) LSD (in rats), such substitution does not predict hallucinogenic potency (in humans) but does predict similarities in mechanism(s) of action; (2) the behavioral (in vivo) effects of LSD, unlike those of some of its congeners, are mediated primarily by central, serotonergic (5-HT) neuronal mechanism although LSD may also have (secondary) dopamine (DA) agonist properties; (3) both the locus and the nature of these LSD-5-HT interactions are unclear: cells arising from B-7, B-8 and B-9 regions of the dorsal-medial raphe may be involved; pretreatment with agents that deplete 5-HT and increase the stereospecific binding of 3H-LSD in vitro (p-chlorophenylalanine; 5,7-dihydroxytryptamine) enhance sensitivity to LSD in vivo.
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Geyer MA, Petersen LR, Rose GJ. Effects of serotonergic lesions on investigatory responding by rats in a holeboard. BEHAVIORAL AND NEURAL BIOLOGY 1980; 30:160-77. [PMID: 7447870 DOI: 10.1016/s0163-1047(80)91041-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Davis M. Neurochemical modulation of sensory-motor reactivity: acoustic and tactile startle reflexes. Neurosci Biobehav Rev 1980; 4:241-63. [PMID: 6106916 DOI: 10.1016/0149-7634(80)90016-0] [Citation(s) in RCA: 269] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The present review argues that the startle reflex is particularly well suited as a model system to analyze how drugs alter stimulus reactivity and reflex excitability. It then reviews all the literature to date on how drugs or lesions that are thought to alter neurochemical transmitter systems affect acoustic and/or tactile startle. Hypotheses are presented to account for how serotonin, dopamine, norepinephrine, acetylcholine, and opiates modulate startle. Effects on startle plasticity such as habituation, sensitization, and potentiation resulting from prior associative learning are also included.
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Aghajanian GK. Mescaline and LSD facilitate the activation of locus coeruleus neurons by peripheral stimuli. Brain Res 1980; 186:492-8. [PMID: 7357465 DOI: 10.1016/0006-8993(80)90997-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Gruzelier JH, Hirsch SR, Weller M, Murphy C. Influence of D-or DL-propranolol and chlorpromazine on habituation of phasic electrodermal responses in schizophrenia. Acta Psychiatr Scand 1979; 60:241-8. [PMID: 495166 DOI: 10.1111/j.1600-0447.1979.tb00272.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Propranolol was found to share the properties of the racemate in facilitating habituation of the electrodermal orienting reflex in schizophrenic patients. This effect appeared independent of influences on levels of skin conductance and non-specific responses. Chlorpromazine did not normalise orienting activity. If the findings from open clinical studies that D-propranolol has anti-psychotic properties are confirmed, the fact that dextro propranolol has only minimal cardiovascular effects may give it important advantages as an anti-psychotic agent. Controlled clinical studies to prove its therapeutic action and neurobiological studies to determine its central mechanisms of action are warranted.
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Geyer MA, Rose GJ, Petersen LR. Mescaline increases startle responding equally in normal and raphe-lesioned rats. Pharmacol Biochem Behav 1979; 10:293-8. [PMID: 450941 DOI: 10.1016/0091-3057(79)90103-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
To test the possible involvement of serotonin-containing cells of the midbrain in mediating the effects of mescaline on startle responding, electrolytic lesions were made in either the dorsal or median raphe nucleus in rats. Decreases in either striatal or hippocampal tryptophan hydroxylase activity confirmed the effectiveness of the lesions. One week later, startle was measured in response to 30 air-puff stimuli for each rat. Median, but not dorsal, raphe lesions increased startle magnitudes throughout the test session. The following day each group was divided into matched halves and were given 60 trials, 30 minutes after intraperitoneal injection of either saline or 10 mg/kg mescaline. Despite the large differences in baseline startle among the groups, mescaline produced comparable 25% increases in startle magnitudes in both sham- and raphe-lesioned animals. This result fails to support the hypothesis that increased startle responding produced by mescaline is mediated by the midbrain raphe nuclei.
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Walters JK, Sheard MH, Davis M. Effects of N,N-dimethyltryptamine (DMT) and 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) on shock elicited fighting in rats. Pharmacol Biochem Behav 1978; 9:87-90. [PMID: 279938 DOI: 10.1016/0091-3057(78)90016-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Rats were tested for shock elicited fighting under various doses of N,N-dimethyltryptamine (0.12, 0.25, 0.50, 1.0, 4.0, 8.0 mg/kg) and 5-methoxy-N,N-dimethyltryptamine (0.06, 0.12, 0.5, 2.0 mg/kg). Both drugs produced an inhibition of fighting at higher doses but no significant effects at lower doses. The effects of these drugs on shock elicited fighting, as well as on other behaviors, thus differ from those of another indole hallucinogen, d-lysergic acid diethylamide, and are discussed in relation to their effects on single unit activity of the raphe-serotonin system and their interaction with other neurotransmitter systems.
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Fuxe K, Ogren SO, Agnati LF, Jonsson G, Gustafsson JA. 5,7-Dihydroxytryptamine as a tool to study the functional role of central 5-hydroxytryptamine neurons. Ann N Y Acad Sci 1978; 305:346-69. [PMID: 280251 DOI: 10.1111/j.1749-6632.1978.tb31533.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Jacobs BL. Dreams and hallucinations: A common neurochemical mechanism mediating their phenomenological similarities. Neurosci Biobehav Rev 1978. [DOI: 10.1016/0149-7634(78)90007-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jacobs BL, Trulson ME, Stern WC. Behavioral effects of LSD in the cat: proposal of an animal behavior model for studying the actions of hallucinogenic drugs. Brain Res 1977; 132:301-14. [PMID: 19128 DOI: 10.1016/0006-8993(77)90423-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In the course of examining the complete dose-response relationship for the behavioral effects of LSD in the cat, we discovered that, in addition to large increases in investigatory and hallucinatory-like responses, two behaviors, not previously reported, are emitted with a high probability under LSD. Beginning from a baseline of essentially zero in saline-treated animals, limb flicks and abortive grooming increase in frequency in direct relation to the dose of LSD administered (2.5, 10, 25 and 50 microgram/kg i.p.) and then decrease at higher doses (100 and 200 microgram/kg). Limb flicks are a species-specific behavior seen in normal cats almost exclusively in response to the presence of a foreign substance, such as water, on the hindpaw or forepaw. In abortive grooming, the cat orients to the body surfaces as if to groom but does not emit the consummatory grooming response (bite, lick or scratch), or emits the response in midair. These behaviors can serve as an animal behavior model for the actions of LSD and related hallucinogens in humans. The specificity of these behavioral changes is indicated by the fact that they are never seen in response to other classes of psychoactive drugs such as D-amphetamine, atropine, caffeine, and cholorpheniramine. They are, however, elicited by compounds such as psilocybin which are structurally and functionally related to LSD. The validity of the model is based on evidence indicating that it is: specific to hallucinogens, dose dependent, observed in a dose range effective in humans, parallels the major parameters of the actions of LSD in humans (see following paper), sensitive, robust, reliable, quantifiable and easy to score.
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Davis M, Gallager DW, Aghamanian GK. Tricyclic antidepressant drugs: attenuation of excitatory effects of d-lysergic acid diethylamide (LSD) on acoustic startle response. Life Sci 1977; 20:1249-57. [PMID: 850475 DOI: 10.1016/0024-3205(77)90499-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Davis M, Walters JK. Psilocybin: biphasic dose-response effects on the acoustic startle reflex in the rat. Pharmacol Biochem Behav 1977; 6:427-31. [PMID: 882579 DOI: 10.1016/0091-3057(77)90180-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The startle reflex was measured in 7 groups of 10 rats each after intraperitoneal injection of saline or 0.25, 0.50, 0.75, 1.0, 2.0, 4.0 or 8.0 mg/kg psilocybin. Low doses (0.75-2.0 mg/kg) increased startle amplitude whereas high doses (4.0-8.0 mg/kg) depressed startle. Selected low (0.71 mg/kg) or high (5.70 mg/kg) doses of psilocin also had a biphasic dose-response effect on startle comparable in magnitude to equimolar doses of psilocybin. This biphasic dose-response relationship of the indole hallucinogen, psilocybin, on startle is consistent with the hypothesis that startle is increased when the firing rates of midbrain raphe neurons are selectively inhibited but is depressed when neurons postsynaptic to raphe cells are also inhibited.
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Davis M, Cedarbaum JM, Aghajanian GK, Gendelman DS. Effects of clonidine on habituation and sensitization of acoustic startle in normal, decerebrate and locus coeruleus lesioned rats. Psychopharmacology (Berl) 1977; 51:243-53. [PMID: 403539 DOI: 10.1007/bf00431631] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Rats were presented with startle-eliciting tones after injection of clonidine (0.01, 0.02, 0.04, 0.08, 0.5, 1.0 or 2.0 mg/kg) or saline. Clonidine potently depressed startle amplitude and the effect was monotonically related todose. Pretreatment with piperoxane (10 mg/kg) antagonized this effect but pretreatment with phentolamine (10 mg/kg) did not. Clonidine still depressed startle in acutely decerebrate rats and in rats with bilateral ablation of the locus coeruleus. Clonidine did not interfere with sensitization to background noise and did not interfere with the ability to startle but instead improved within-session habituation. The results represent one of the few instances in the literature where a drug appears to improve habituation without directly interfering with the ability to respond. The possibility that clonidine might affect startle by stimulating central epinephrine rather than norepinephrine receptors is discussed.
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Eliasson M, Meyerson BJ. The effects of lysergic acid diethylamide on copulatory behaviour in the female rat. Neuropharmacology 1977; 16:37-44. [PMID: 138098 DOI: 10.1016/0028-3908(77)90044-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Frontali M, Amorico L, De Acetis L, Bignami G. A pharmacological analysis of processes underlying differential responding: a review and further experiments with scopolamine, amphetamine, lysergic acid diethylamide (LSD-25), chlordiazepoxide, physostigmine, and chlorpromazine. BEHAVIORAL BIOLOGY 1976; 18:1-74. [PMID: 791242 DOI: 10.1016/s0091-6773(76)91764-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Davis M, Aghajanian GK. Effects of apomorphine and haloperidol on the acoustic startle response in rats. Psychopharmacology (Berl) 1976; 47:217-23. [PMID: 823557 DOI: 10.1007/bf00427605] [Citation(s) in RCA: 83] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A series of 3 experiments tested the effects of 0.01, 0.04, 0.19, 0.75, 3.00, and 6.00 mg/kg apomorphine and 0.13, 0.25, and 0.50 haloperidol on the acoustic startle response in rats. Apomorphine markedly facilitated startle amplitude for about 40 min after injection and then depressed startle over the next 40 min. Both the early facilitory and later inhibitory effects were directly related to the dose. Haloperidol (0.5 mg/kg--given 30 min before) completely blocked both the early facilitory and the later depressant effect of apomorphine (3 mg/kg). Haloperidol alone had only a slight depressant effect on startle. The data support the conclusion that DA receptor stimulation enhances acoustic startle amplitude and indicate that a previous report failed to find an effect of apomorphine on startle because startle was only measured 40 min after injection.
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Davis M, D'Aquila R. Acute intravenous infusion in freely moving rats through the sagittal and transverse sinuses. Pharmacol Biochem Behav 1976; 4:469-72. [PMID: 935217 DOI: 10.1016/0091-3057(76)90065-4] [Citation(s) in RCA: 5] [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
A technique is described which allows drugs to be injected intravenously using the junction of the sagittal and transverse sinuses as the point of entry into the venous system. The procedure is rapid and uses conventional stereotaxic techniques. Subsequent restraint of movement during drug infusion is minimal. Using this method, 15 mug/kg d-lysergic acid diethylamide produced an increase in acoustic startle amplitide within about 1-2 min which lasted for about 25 min.
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Davis M, Sheard MH. p-Chloroamphetamine (PCA): acute and chronic effects on habituation and sensitization of the acoustic startle response in rats. Eur J Pharmacol 1976; 35:261-73. [PMID: 129331 DOI: 10.1016/0014-2999(76)90228-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In a series of 6 experiments the effects of p-chloroamphetamine (PCA) on the acoustic startle response in rats were investigated. 15 min after 5 mg/kg PCA startle amplitude was inhibited, 2-15 hr after PCA startle was facilitated. Rate of habituation however was not altered. Both the inhibitory and excitatory effects of PCA were blocked by pretreatment with p-chlorophenylalanine but not by alpha-methyl-p-tyrosine. 24 hr, 1 week and 4 weeks after PCA, initial startle amplitude was unchanged but PCA increased rate of sensitization over successive tone blocks. Increased sensitization was most pronounced at 10 mg/kg and absent at 2.5 mg/kg. The early inhibitory effect of PCA but not the later facilitatory effect was eliminated by reducing the level of background noise. The results suggest that inhibition of startle sensitization is associated with enhanced release of serotonin (5-HT) whereas enhancement of startle sensitization is associated with 5-HT depletion.
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Brooks DC. The effect of LSD upon sponstaneous PGO wave activity and REM sleep in the cat. Neuropharmacology 1975; 14:847-57. [PMID: 174025 DOI: 10.1016/0028-3908(75)90113-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Davis M, Sheard MH. Effects of lysergic acid diethylamide (LSD) on temporal recovery (pre-pulse inhibition) of the acoustic startle response in the rat. Pharmacol Biochem Behav 1975; 3:861-8. [PMID: 1208627 DOI: 10.1016/0091-3057(75)90118-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In a series of 6 experiments 40 mug/kg d-lysergic acid diethylamide (LSD) augmented acoustic startle amplitude in rats when long intertone intervals (4, 8, 16, or 32 sec) were used but not when short interstimulus intervals were used (0.02, 0.1, 0.5, 1, or 2 sec). In contrast, 8 mg/kg d-amphetamine augmented startle when either long or short interstimulus intervals were used. The results suggest that LSD augments startle by accelerating the decay of pre-pulse inhibition (temporal recovery process) which may be one mechanism by which LSD can alter sensory processing.
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Davis M, Svensson TH, Aghajanian GK. Effects of d- and l-amphetamine on habituation and sensitization of the acoustic startle response in rats. Psychopharmacology (Berl) 1975; 43:1-11. [PMID: 1172255 DOI: 10.1007/bf00437607] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In a series of 3 experiments the effects of 2, 4, 8, or 16 mg/kg d-amphetamine and 4, 8, 16, or 32 mg/kg l-amphetamine on acoustic startle amplitude in the rat were investigated. d-Amphetamine was 4--5 times as potent as l-amphetamine in augmenting startle amplitude. Startle potentiation was associated with vigorous stereotypies but the resultant cage movement could not account for the change in startle. Pretreatment with alpha-methyl-p-tyrosine (100 mg/kg, 1 hr before) had only a slight depressant effect on startle but essentially eliminated augmentation of startle by either d-amphetamine (8 mg/kg) or l-amphetamine (32 mg/kg). d-Amphetamine did not have a direct effect on startle but instead enhanced sensitization produced by the startle stimuli without altering sensitization produced by background white noise or habituation. The results suggest that startle sensitization is enhanced by increased availability of catecholamines and, by virtue of the different potencies of the d- and l-isomers, that dopamine and norepinephrine may affect startle differently.
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Geyer MA, Warbritton JD, Menkes DB, Zook JA, Mandell AJ. Opposite effects of intraventricular serotonin and bufotenin on rat startle responses. Pharmacol Biochem Behav 1975; 3:687-91. [PMID: 1187731 DOI: 10.1016/0091-3057(75)90193-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Rat startle responses to air puffs were monitored in a stabilimeter during the intraventricular infusion of various doses of 5-hydroxytrptamine (5-HT) or the putative hallucinogenic congener of 5-HT, 5-hydroxy-N, N-dimethyltrytamine (5-HDMT) or saline. Qualitativity opposite effects were observed, with 5-HT producing a dose-dependent decrease in responsivity and 5-HDMT increasing the magnitude of startle responses. No specific effects of either compound could be demonstrated on the presumably separable processes of sensitization and habituation. The results are discussed in the context of a central serotonergic system which facilitates behavioral inhibition and which is antagonized by indoleamine hallucinogens.
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Davis M, Sheard MH. Biphasic dose-response effects of N-N-dimethyltryptamine on the rat startle reflex. Pharmacol Biochem Behav 1974; 2:827-9. [PMID: 4533618 DOI: 10.1016/0091-3057(74)90116-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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