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At least 73 records · Page 4Linked to original sources

PubMed1996

Effects of neurotensin on neurons in the rat central amygdaloid nucleus in vitro.

The effects of neurotensin (NT) on neurons in the central amygdaloid nucleus (ACe) were investigated in rat brain slice preparations by adding the peptide to the perfusing medium. Of 115 ACe neurons, 69 cells (60%) showed excitatory responses and 10 cells (9%) showed inhibitory responses to application of NT. The excitatory response to NT was observed in a dose-dependent manner and the threshold concentration was approximately 3 x 10(-9) M. The excitatory effects of NT persisted under blockade of synaptic transmission. The NT fragment neurotensin 8-13 and the NT analogue neuromedin N showed effects similar to those of NT, whereas the NT fragment neurotensin 1-8 had no effect on ACe neurons. Of 43 neurons in the septal nucleus, 8 cells (19%) and 3 cells (7%) showed excitatory and inhibitory responses, respectively, to NT. The results suggest that NT exerts a potent excitatory effect on ACe neurons through a direct action on specific receptors, in which NT may play a role in amygdala-relevant functions.

Amygdala↗

PubMed1988

Effect of catecholamine-receptor antagonists on feeding-related neuronal activity in the central amygdaloid nucleus of the monkey: a microiontophoretic study.

1. Neuronal activity in the central amygdaloid nucleus (ACE) was recorded during a visually guided bar-press feeding task, and the modulatory effects of catecholaminergic blockers were investigated. 2. The feeding task had the following four phases: 1) a cue light to signal the start of bar press, 2) bar press, 3) a short cue tone followed by food delivery, and 4) ingestion reward. Of 278 cells observed, 176 (63%) increased or decreased their discharge rates in one or more phases of the feeding task. Of these, 60 (34%) responded to the cue light, 81 (46%) to the bar press, 66 (37%) to the cue tone, and 176 (100%) during the reward period. In the ingestion reward phase, firing of 128 (73%) increased and firing of 48 (27%) decreased. The reward-related response depended on the nature of food. In the trials with aversion food, some neurons increased firing (n = 6), whereas others showed opposite firing changes (n = 10). 3. The decreased firing rate during the reward period was greatly attenuated in the no-reward tasks (n = 29) and was blocked by electrophoretic application of a beta-adrenoceptive antagonist [sotalol (SOT), n = 26]. Noradrenaline (NA) application mimicked the inhibitory effect on the reward-related activity during extinction trial (n = 4). These results suggest that the decreased firing rate observed during the reward period was modulated by beta-adrenoreceptors. 4. Of 32 neurons tested, the activity of 8 (25%) and 14 (44%) were enhanced by the cue light or bar press, respectively. These effects were attenuated by electrophoretic application of a dopamine (DA) antagonist [spiperone (SPP)] but not by SOT. This indicates that dopaminergic inputs may be related to recognition of visual signals and to motor initiation during the monkey feeding paradigm.

Action Potentials↗

PubMed1991

Role of amygdaloid nucleus in the correlation between the heart and the acupoint neiguan in rabbits.

Amygdaloid nucleus (AMYG) could converge and integrate the signals from electroacupuncture (EA) at Neiguan (P 6) and acute myocardial ischemia (AMI) in rabbits. And EA could regulate the changes in the discharge of single units in AMYG caused by AMI, that is, EA inhibited the increased frequency, and reversed the decreased frequency. This suggested that AMYG is an important link in correlation between the heart and the acupoint Neiguan, providing an experimental basis for the Theory of Channel--Viscera Correlation.

Acupuncture Points↗

PubMed1997

Effects of vasopressin and involvement of receptor subtypes in the rat central amygdaloid nucleus in vitro.

Effects of arginine-vasopressin (AVP) on neurons in the central amygdaloid nucleus (ACe) were investigated with rat brain slice preparations using extracellular recording methods. Of 160 ACe neurons tested, 70 cells (44%) were excited and 9 cells (6%) were inhibited by bath application of AVP at 3 x 10(-7) M. The excitatory effects of AVP were dose-dependent and the threshold concentration was approximately 10(-10) to 10(-9) M. The excitatory effects of AVP persisted under blockade of synaptic transmission by perfusing with Ca2+-free and high-Mg2+ medium, whereas the inhibitory effects were abolished by synaptic blockade. AVP-induced effects were mimicked by a V1-receptor agonist and completely blocked by a selective V1-antagonist. V2-agonist produced no effects on ACe neurons and V2-antagonist had no effect on AVP-induced excitation. These results showed that the excitatory effect of AVP on ACe neurons was produced by a direct action through the V1-receptors, whereas the inhibitory response of ACe neurons to AVP seemed to be produced by an indirect action. The results of this study suggest that AVP is involved in the amygdala-relevant functions as a neurotransmitter or a neuromodulator.

Amygdala↗

PubMed1995

Inhibition of neurons in the rat medial amygdaloid nucleus in vitro by somatostatin.

Effects of somatostatin (SRIF) on neurons in the medial amygdaloid nucleus were investigated in rat brain slice preparations, using extracellular recordings. Following bath application of SRIF at 10(-7) - 10(-6) M, 63 of 81 (78%) medial amygdala neurons showed an inhibitory response. The inhibitory effect of SRIF was dose dependent, and the threshold concentration was approximately 10(-9) M. The inhibitory response to SRIF persisted during synaptic blockade in two-thirds of neurons tested. The inhibitory effect of SRIF was reduced by picrotoxin, a GABAA receptor antagonist, in one-third of neurons. These results suggest that SRIF exerts an inhibitory effect on medial amygdala neurons through either a direct action on SRIF receptors or a GABAergic synaptic involvement.

Amygdala↗

PubMed1994

In vivo voltammetric measurement of evoked extracellular dopamine in the rat basolateral amygdaloid nucleus.

1. The in vivo measurement of evoked extracellular dopamine was established in the basolateral amygdaloid nucleus (BAN) using fast-scan cyclic voltammetry at carbon-fibre microelectrodes. 2. The identification of evoked extracellular dopamine in the BAN was based on anatomical, electrochemical and pharmacological criteria. Electrochemical and pharmacological evidence indicated that the species was a catecholamine. Mesencephalic sites eliciting overflow and amygdaloid sites supporting overflow correlated well with the mesoamygdaloid dopamine innervation. 3. Marked differences in the dynamics and magnitude of evoked dopamine overflow were observed in the BAN, caudate-putamen and amygdalo-striatal transition area. The results underscore the importance of making spatially resolved measurements of extracellular dopamine in the amygdala. 4. Mesoamygdaloid dopamine neurons have similar release characteristics as mesostriatal dopamine neurons but share with mesoprefrontal cortical dopamine neurons the ability to use a greater percentage of intraneuronal dopamine stores for release.

Amygdala↗

PubMed1985

Morphology of peptide-containing neurons in the rat basolateral amygdaloid nucleus.

The peroxidase-antiperoxidase (PAP) immunohistochemical technique was used to identify neurons in the basolateral amygdaloid nucleus (BL) that contain vasoactive intestinal polypeptide (VIP), somatostatin (SOM) or cholecystokinin (CCK). Examination of immunostained neurons demonstrated that most, if not all, of these peptide-containing cells correspond to spine-sparse class II neurons recognized in Golgi studies. Each type of peptide-containing perikaryon in BL exhibits a distinct size distribution which, in part, accounts for the broad size range of class II neurons noted in Golgi studies.

Amygdala↗

PubMed2001

[Effect of estrogen on dopamine release evoked by electric stimulation of central amygdaloid nucleus].

In vivo fast cyclic voltammetry (FCV) was used to investigate dopamine (DA) release from central amygdaloid nucleus (CAN) of ovariectomized (OVX), estrogen-treated and normal female rats. Radioimmunoassay was used to measure the serum concentration of estradiol (E(2)). DA release was significantly higher in OVX rats treated with estradiol benzoate (EB) as compared with controls. The DA release due to electric stimulation is dose-dependent on serum concentration of estradiol, suggesting that estrogen may play an important role in regulating DA release from CAN.

Amygdala↗

PubMed1989

Effect of electro-acupuncture of "Neiguan" on spontaneous discharges of single unit in amygdaloid nucleus in rabbits.

In this paper, the regularity on spontaneous discharges of the single unit in amygdaloid nucleus (AMYG) in rabbits were analyzed and whether the signal of Electro-acupuncture (EA) at Neiguan (P 6) can reach the AMYG was further observed with the technique of glass microelectrode. It was found that the signals of EA at Neiguan can reach AMYG and activate or inhibit the electrical activity of some neurons, manifesting two response patterns: frequency-increasing and frequency-decreasing. Additionally, the same neuron had a different response to the signals of EA at Neiguan and Zusanli (St 36), suggesting that a relative specificity of acupoints is present.

Acupuncture Therapy↗

PubMed1993

Effect of differential rearing on synapses and soma size in rat medial amygdaloid nucleus.

The effects of differential rearing on synaptic morphology and neuronal size were examined in the medial amygdaloid nucleus (MAN) of adult rats. Forty-day-old male rats were housed in one of three ways: individually (isolated condition, IC); with four males per cage (unisexual condition, UC); or with two males and two females per cage (social condition, SC). After 2 months, the animals were prepared for electron and light microscopy. Although there was no statistically significant difference in number of synapses per unit volume in MAN, the number of perforated (P) synapses, which are characterized by discontinuities in the postsynaptic density, were significantly greater in the UC and the SC than in the IC. The length of synaptic contact zone of P synapses was also longer in both the UC and the SC compared with the IC, whereas the length of nonperforated synapses was longer only in the SC. Soma area was also larger in the SC compared with the IC. These results demonstrate that exposure to different rearing conditions, in which the pheromonal environment can be substantially different, can induce striking morphological changes in both synapses and neurons in the MAN of adult rats.

Amygdala↗

PubMed1987

Cholinergic manipulations in the rat basolateral amygdaloid nucleus on locomotor activity induced by amphetamine.

Microinjections of cholinergic antagonists in the vicinity of the basolateral amygdaloid nucleus produced a marked reduction of amphetamine-induced hyperactivity when amphetamine was administered i.p. in relatively large doses (1.5 mg/kg). Cholinergic agonists enhanced locomotor activity induced by relatively small doses of amphetamine (0.5 mg/kg). These observations suggest that cholinergic activity in the amygdala modulates the locomotor response to amphetamine.

Amphetamine↗

PubMed1997

Increase of the aversive value of taste stimuli following ibotenic acid lesion of the central amygdaloid nucleus in the rat.

Male Sprague-Dawley rats received bilateral ibotenic acid lesions of the central amygdaloid nucleus (CeA) and were compared to sham-lesioned rats in their response to different concentrations of saccharin and quinine solutions. In two-bottle choice test situation, the lesioned rats exhibited a lower saccharin preference at concentrations of 2.5; 7.5 and 25 mM, while their aversion towards quinine and the highest concentration of saccharin (50 mM) was increased. In a one-bottle test, the lesioned rats showed consistent decreases in their consumption of 2.5 and 7.5 mM saccharin solutions whereas their intake of 0.9 mM solution of saccharin was equal to that of the sham-lesioned rats. The lesion of the CeA had no significant effects on the acquisition of conditioned taste aversion. There was less postoperative weight gain in lesioned rats as compared to sham-lesioned animals but the lesion had no significant effect on daily water intake. These findings suggest that the CeA plays an important role in the normal response to exteroceptive food stimuli via modulation of the aversive value of taste stimuli. The results are discussed in the context of an interaction between the CeA and the lateral hypothalamus (LH) in the modulation of palatability and feeding behavior.

Amygdala↗

PubMed1992

Conditioning stimulation of the central amygdaloid nucleus inhibits the jaw-opening reflex in the cat.

To elucidate a function of the central amygdaloid nucleus (ACE) in the trigeminal system, the ACE conditioning effect on the jaw-opening reflex (JOR) regarded as a nociceptive reflex was investigated in the cat anesthetized with pentobarbital sodium. The JOR to molar tooth pulp stimulation with an intensity 1.2-1.5 times the threshold was recorded in the ipsilateral digastric muscle. As conditioning stimulation, a train of 33 rectangular pulses (0.5 ms in duration) at 330 Hz with an intensity of 300 microA was applied to the ipsilateral ACE. The conditioning stimulation inhibited a JOR that had a latency of 7.90 +/- 0.88 ms (n = 36). The inhibition was maximum (83.1 +/- 11.2%) at a conditioning-test (C-T) interval of 110 ms and continued for C-T intervals of up to 1,000 ms. Likewise, microinjection of 0.5 M monosodium glutamate (10 microliters) into the ACE-inhibited the JOR for approximately 10 min. Additionally, the ACE conditioning stimulation inhibited the JOR induced by the stimulation of the sensory trigeminal nuclear complex in a similar manner, but not the jaw-opening response induced by the stimulation of the trigeminal motor nucleus (Mo V). Also, the conditioning stimulation influenced neither the evoked potentials induced by the tooth pulp stimulation at the main sensory and rostral nuclei nor the jaw-closing reflex induced by the stimulation of the mesencephalic trigeminal nucleus (Mes V). These results suggest that the excitation of the cell bodies in the ACE exerts an inhibitory modulation on the JOR with no effect on the non-nociceptive reflex such as the jaw-closing reflex at the level of Mo V.

Amygdala↗

PubMed1998

Anatomical interactions between the central amygdaloid nucleus and the hypothalamic paraventricular nucleus of the rat: a dual tract-tracing analysis.

Axonal connections between the amygdala and the hypothalamic paraventricular nucleus were examined by combined anterograde-retrograde tract tracing. Iontophoretic injections of the retrograde tracer Fluorogold were placed in the paraventricular nucleus, and the anterograde tracer PHA-L in the ipsilateral central or medial amygdaloid nuclei. Single and double-label immunohistochemistry were used to detect tracers. Single label anterograde and retrograde tracing suggest limited evidence for direct connections between the central or medial amygdala and the paraventricular nucleus. In general, scattered PHA-L-positive terminals were seen in autonomic subdivisions of the paraventricular nucleus (lateral parvocellular, dorsal parvocellular and ventral medial parvocellular subnuclei) following central or medial amygdaloid nucleus injection. Double-label studies indicate that central and medial amygdaloid nucleus efferents contact paraventricular nucleus-projecting cells in several forebrain nuclei. In the case of central nucleus injections, PHA-L positive fibers occasionally contacted Fluorogold-labeled neurons in the anteromedial, ventromedial and preoptic subnuclei of the bed nucleus of the stria terminalis. Overall, such contacts were quite rare, and did not occur in the bed nucleus of the stria terminalis regions showing greatest innervation by the central amygdaloid nucleus. In contrast, medial amygdala injections resulted in a significantly greater overlap of PHA-L labeling and Fluorogold-labeled neurons, with axosomatic appositions observed in medial divisions of the bed nucleus of the stria terminalis, anterior hypothalamic area and preoptic area. The results provide anatomical evidence that a substantial proportion of amygdaloid connections with hypophysiotrophic paraventricular nucleus neurons are likely multisynaptic, relaying in different subregions of the bed nucleus of the stria terminalis and hypothalamus.

Amygdala↗

PubMed1988

Projections of the intermediate subdivision of the central amygdaloid nucleus to the bed nucleus of the stria terminalis and medial diencephalon.

The forebrain projections of the intermediate subdivision of the central amygdaloid nucleus (CI) were studied using the horseradish peroxidase (HRP) retrograde transport technique. Injections of wheatgerm agglutinin-conjugated HRP into the bed nucleus of the stria terminalis and medial thalamus resulted in moderate retrograde labeling in CI while injections into the medial hypothalamus produced very dense cell labeling in CI. The dorsal hypothalamic area appears to be the main target of the efferents to the hypothalamus. Although previous histochemical studies have suggested that CI may be part of the lateral subdivision of the central nucleus (CL), the projection of CI to the medial diencephalon clearly distinguishes CI from CL.

Amygdala↗

PubMed1983

Increase of FSH secretion in immature female rats following lesioning of the medial amygdaloid nucleus.

Immature female rats were bilaterally lesioned or sham-lesioned in the anterior part of the medial amygdaloid nucleus (AMN) at 21 days of age, and the serum FSH and LH concentrations were estimated in groups of rats autopsied at daily intervals from day 21 through day 28. Whereas the LH concentration did not differ between lesioned females and the controls, a highly significant elevation of the circulating FSH level was recorded in the lesioned rats from day 22 till day 24. A further experiment demonstrated that similar lesions did not change the FSH and LH-inhibiting effect of estrogen in rats that were ovariectomized on day 22, daily injected with 0.05 microgram estradiol benzoate per 100 g b.w. on days 22 and 23, and sacrificed 24 hr after the last injection. The results suggest that the AMN exerts a restraining influence on the hypophyseal FSH secretion around 21 days of age, and that this inhibitory activity does not depend upon sensitization to the negative feed-back of estrogen.

Amygdala↗

PubMed1997

[Role of substance P in pressor response of central amygdaloid nucleus to glutamate].

Substance P (SP)-immunoreactive cells and the axon terminals are widely distributed in the central amygdaloid nucleus (AC) and its important projection areas. The present study showed that (1) Excitation of the AC by glutamate (Glu) or injection of SP into the AC projection areas: locus coeruleus (LC), nucleus parabrachialis (NPB), periaqueductal gray matter (PAG) or lateral hypothalamus-perifornical region (LH/PF), all elicited pressor response. (2) Preinjection of DPDPDT (a SP antagonist) into bilateral LC, NPB, PAG or LH/PF could attenuate the AC pressor response to Glu. (3) Intra-RVLM (rostral ventrolateral medulla) preinjection of either phentolamine, propranolol or atropine (but not GDEE, a Glu antagonist) could also reduce the AC pressor response. Taken together with our previous findings that the alpha-, beta-, M-receptors in RVLM mediated the pressor response to LC excitation, alpha-receptors mediated the NPB pressor response, alpha- and beta-receptors mediated the PAG pressor response; these results indicate that the SPergic projections of the AC not only directly act upon the brainstem pressor areas (LC, NPB, PAG)-RVLM system, but also indirectly via the LH/PF act upon the brainstem pressor areas-RVLM system to induce the pressor response.

Amygdala↗

PubMed1995

The adrenergic innervation of the rat central amygdaloid nucleus: a light and electron microscopic immunocytochemical study using phenylethanolamine N-methyltransferase as a marker.

Using immunocytochemistry of phenylethanolamine N-methyltransferase for light and electron microscopy, investigations were carried out to document the morphology of adrenergic afferents innervating the rat central amygdaloid nucleus and to analyse the manner in which contacts with neurons of the nucleus are formed. With the light microscope, dense terminal plexus of phenylethanolamine N-methyltransferase-immunoreactive axons with typical large boutons (diameter > 1 micron) were found in the medial central nucleus, extending into its ventral subdivision and the adjacent intra-amygdaloid portion of the bed nucleus of the stria terminalis. Electron microscopy of the medial central nucleus showed phenylethanolamine N-methyltransferase-immunoreaction product in the cytoplasm of intervaricose axons and boutons. Large adrenergic boutons contained numerous small clear vesicles and, occasionally, large dense-cored vesicles. In serial sections, most boutons formed synaptic contacts. Synapses of immunoreactive terminals were mainly of the asymmetric type and localized preferentially on medium sized to small dendrites and dendritic spines. Structures postsynaptic to adrenergic boutons were often additionally contacted by non-labelled terminals. The study gives evidence that adrenergic afferents exert a direct synaptic influence on medial central nucleus neurons. The peripheral localization of the majority of adrenergic synapses, their asymmetric configuration, and the presence of non-adrenergic synapsing terminals in their immediate vicinity indicate that the major component of the adrenergic input is of an excitatory nature, and is integrated with innervation from other sources.

Amygdala↗