Micro-injection of 3H-acetylcholine, 14C-serotonin and 3H-norepinephrine into the hypothalamus of the rat: Diffusion into tissue and ventricles

Myers, R.D.; Tytell, Michael; Kawa, A.; Rudy, Thomas A.

doi:10.1016/0031-9384(71)90143-0

Cited by 80 publications

(9 citation statements)

References 21 publications

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“…That NMDA in the dorsal hippocampus exerts mainly temporary effects is further corroborated by the results of experiment 4, where rats infused with NMDA only before tone test 1 exhibited reduced freezing as compared with VEH rats during tone test 1, but not 2. Moreover, with the small infusion volume (0.5 l/side) and fine infusion cannulae (34 gauge) used in the present study, the estimated spread of the infused substances, occurring preferentially dorsally along the external wall of the infusion cannula, is Ͻ1 mm (Myers, 1966;Myers et al, 1971;Routtenberg, 1972). Thus, it can be assumed that differences observed between rats infused with VEH as compared to those infused with MK-801 or NMDA reflected a temporary alteration of neuronal activity by blockade or stimulation of dorsal hippocampal NMDA receptors.…”

Section: Dorsal Hippocampal Infusion Of Mk-801 and Nmdamentioning

confidence: 82%

Dorsal hippocampus and classical fear conditioning to tone and context in rats: Effects of local NMDA‐receptor blockade and stimulation

2003

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ABSTRACT:Consistent with the importance of the hippocampus in learning more complex stimulus relations, but not in simple associative learning, the dorsal hippocampus has commonly been implicated in classical fear conditioning to context, but not to discrete stimuli, such as a tone. In particular, a specific and central role in contextual fear conditioning has been attributed to mechanisms mediated by dorsal hippocampal N-methyl-D-aspartate (NMDA)-type glutamate receptors. The present study characterized the effects of blockade or tonic stimulation of dorsal hippocampal NMDA receptors by bilateral local infusion of the noncompetitive NMDA receptor antagonist MK-801 (dizocilpine maleate; 6.25 g/side) or of NMDA (0.7 g/side), respectively, on classical fear conditioning to tone and context in Wistar rats. Freezing was used to measure conditioned fear. Regardless of whether conditioning was conducted with tone-shock pairings or unsignaled footshocks (background or foreground contextual conditioning), both NMDA and MK-801 infusion before conditioning resulted in reduced freezing during subsequent exposure to the conditioning context. Freezing during subsequent tone presentation in a new context, normally resulting from conditioning with tone-shock pairings, was not impaired by MK-801 but was strongly reduced by NMDA infusion before conditioning; this freezing was also reduced by NMDA infusion before tone presentation (in an experiment involving NMDA infusions before conditioning and subsequent tone presentation to assess the role of state-dependent learning). It was assessed whether unspecific infusion effects (altered sensorimotor functions, state dependency) or infusion-induced dorsal hippocampal damage contributed to the observed reductions in conditioned freezing. Our data suggest that formation of fear conditioning to context, but not tone, requires NMDA receptor-mediated mechanisms in the dorsal hippocampus. As indicated by the effects of NMDA, some dorsal hippocampal processes may also contribute to fear conditioning to tone. The role of the dorsal hippocampus and local NMDA receptor-mediated processes in fear conditioning to tone and context is discussed in comparison with ventral hippocampal processes.

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Section: Dorsal Hippocampal Infusion Of Mk-801 and Nmdamentioning

confidence: 82%

Dorsal hippocampus and classical fear conditioning to tone and context in rats: Effects of local NMDA‐receptor blockade and stimulation

2003

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“…Given that all infusion sites were located in dorsal hippocampus, we assume that most to all subregions within that area (CA1, CA3, and dentate gyrus) were affected. Given the infusion volume (1 lL) and size of infusion cannulae (26 gauge) used in the present study, the estimated spread of the infused substances was approximately 1 mm (Myers, 1966;Myers et al, 1971;Routtenberg, 1972). Therefore, it can be assumed that the spread of the drug was well within the dorsal regions of the hippocampus and that any differences between vehicle and drug-infused rats reflected a pharmacological alteration of dorsal hippocampal function.…”

Section: Discussionmentioning

confidence: 98%

Intrahippocampal infusion of the I_h blocker ZD7288 slows evoked theta rhythm and produces anxiolytic‐like effects in the elevated plus maze

2012

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Hippocampal theta rhythm has been associated with a number of behavioral processes, including learning and memory, spatial behavior, sensorimotor integration and affective responses. Suppression of hippocampal theta frequency has been shown to be a reliable neurophysiological signature of anxiolytic drug action in tests using known anxiolytic drugs (i.e., correlational evidence), but only one study to date (Yeung et al. (2012) Neuropharmacology 62:155-160) has shown that a drug with no known effect on either hippocampal theta or anxiety can in fact separately suppress hippocampal theta and anxiety in behavioral tests (i.e., prima facie evidence). Here, we attempt a further critical test of the hippocampal theta model by performing intrahippocampal administrations of the Ih blocker ZD7288, which is known to disrupt theta frequency subthreshold oscillations and resonance at the membrane level but is not known to have anxiolytic action. Intrahippocampal microinfusions of ZD7288 at high (15 µg), but not low (1 µg) doses slowed brainstem-evoked hippocampal theta responses in the urethane anesthetized rat, and more importantly, promoted anxiolytic action in freely behaving rats in the elevated plus maze. Taken together with our previous demonstration, these data provide converging, prima facie evidence of the validity of the theta suppression model.

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“…With the small infusion volume (0.5 mL/side) and fine infusion cannulae (26 gauge) used in the present study, the estimated spread of the infused substances was ,1 mm (Myers et al 1971;Routtenberg 1972;Bast and Feldon 2003). It is, therefore, likely that differences between drug conditions (demonstrated within subjects) can be attributed to the temporary Cold Spring Harbor Laboratory Press on May 12, 2018 -Published by learnmem.cshlp.org Downloaded from alteration of neuronal activity by stimulation of GABA A receptors within the ACgx.…”

Section: Discussionmentioning

confidence: 99%

Role of the anterior cingulate cortex in the retrieval of novel object recognition memory after a long delay

et al. 2017

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Previous in vivo electrophysiological studies suggest that the anterior cingulate cortex (ACgx) is an important substrate of novel object recognition (NOR) memory. However, intervention studies are needed to confirm this conclusion and permanent lesion studies cannot distinguish effects on encoding and retrieval. The interval between encoding and retrieval tests may also be a critical determinant of the role of the ACgx. The current series of experiments used micro-infusion of the GABAA receptor agonist, muscimol, into ACgx to reversibly inactivate the area and distinguish its role in encoding and retrieval. ACgx infusions of muscimol, before encoding did not alter NOR assessed after a delay of 20 min or 24 h. However, when infused into the ACgx before retrieval muscimol impaired NOR assessed after a delay of 24 h, but not after a 20-min retention test. Together these findings suggest that the ACgx plays a time-dependent role in the retrieval, but not the encoding, of NOR memory, neuronal activation being required for the retrieval of remote (24 h old), but not recent (20 min old) visual memory.

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Micro-injection of 3H-acetylcholine, 14C-serotonin and 3H-norepinephrine into the hypothalamus of the rat: Diffusion into tissue and ventricles

Cited by 80 publications

References 21 publications

Dorsal hippocampus and classical fear conditioning to tone and context in rats: Effects of local NMDA‐receptor blockade and stimulation

Dorsal hippocampus and classical fear conditioning to tone and context in rats: Effects of local NMDA‐receptor blockade and stimulation

Intrahippocampal infusion of the I_h blocker ZD7288 slows evoked theta rhythm and produces anxiolytic‐like effects in the elevated plus maze

Role of the anterior cingulate cortex in the retrieval of novel object recognition memory after a long delay

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Micro-injection of 3H-acetylcholine, 14C-serotonin and 3H-norepinephrine into the hypothalamus of the rat: Diffusion into tissue and ventricles

Cited by 80 publications

References 21 publications

Dorsal hippocampus and classical fear conditioning to tone and context in rats: Effects of local NMDA‐receptor blockade and stimulation

Dorsal hippocampus and classical fear conditioning to tone and context in rats: Effects of local NMDA‐receptor blockade and stimulation

Intrahippocampal infusion of the Ih blocker ZD7288 slows evoked theta rhythm and produces anxiolytic‐like effects in the elevated plus maze

Role of the anterior cingulate cortex in the retrieval of novel object recognition memory after a long delay

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Intrahippocampal infusion of the I_h blocker ZD7288 slows evoked theta rhythm and produces anxiolytic‐like effects in the elevated plus maze