Cardiovascular Responses to NMDA Injected into Nuclei of Hypothalamus or Amygdala in Conscious Rats

Gören, M. Zafer; Akıcı, Ahmet; Berkman, Kemal; Onat, Filiz

doi:10.1159/000028410

Cited by 13 publications

(6 citation statements)

References 33 publications

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“…The present results showed the central effect of ketamine on blood pressure increase, which is consistent with the results of previous studies 14,15,21) . In addition, the latency and duration of blood pressure increase were similar to those obtained in the results of previous studies in which NMDA was administered to the amygdala to induce blood pressure increase 22) . In the present study, the latency before blood pressure increase was long with considerable variations.…”

Section: Discussionsupporting

confidence: 85%

Increase in Blood Pressure by Local Injection of Ketamine into the Amygdala in Rats

Morimoto

Koyama

Murakawa

2021

Biological & Pharmaceutical Bulletin

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To confirm that an increase in blood pressure induced by ketamine is mediated through the central nervous system, we examined the effect of ketamine, applied directly to the amygdala, on blood pressure. Six male Sprague-Dawley rats were used in the study. Under head-restrained and unanesthetized condition, 0.2 μl (5 mg/ml) of ketamine was injected in and around the amygdala at a flow rate of 0.2 μl/min through a glass pipette, and the blood pressure was recorded while monitoring the state of the animals by electroencephalogram and electromyogram. After ketamine injection, the injection site was marked by Pontamine Sky Blue infusion. Blood pressure was increased by ketamine injection into the basolateral and central nuclei of the amygdala, endopiriform nucleus and piriform cortex. In a total of 11 responses, an increase in blood pressure started with a mean latency of 193.5 ± 43.0 sec, reached its peak 180.2 ± 23.3 sec after the response onset, then gradually returned to the baseline with mean duration of 706.7 ± 113.5 sec. The mean fluctuation was 17.1 ± 2.5 mmHg. We revealed that blood pressure fluctuations induced by ketamine are associated with the amygdala. Elucidation of the mechanism of ketamine-induced blood pressure increase will lead to understanding of the mechanism of side effects of ketamine, and will contribute to its appropriate use.

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Section: Discussionsupporting

confidence: 85%

Increase in Blood Pressure by Local Injection of Ketamine into the Amygdala in Rats

Morimoto

Koyama

Murakawa

2021

Biological & Pharmaceutical Bulletin

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“…Disruption of γ-aminobutyric acid (GABA)-mediated neurotransmission in the DMH evokes increases in arterial blood pressure, heart rate, peripheral sympathetic nerve activity, and plasma catecholamine levels in both conscious and anesthetized rats, suggesting that the GABAergic system in the DMH exerts a tonic inhibitory influence over the sympathetic nervous system (4 -6). In addition, the activation of NMDA receptors in the DMH evokes significant increases in blood pressure and heart rate (7,8). These results provide evidence for the involvement of the DMH in the central regulation of cardiovascular functions.…”

Section: Introductionmentioning

confidence: 59%

Extracellular Hypothalamic γ-Aminobutyric Acid (GABA) and L-Glutamic Acid Concentrations in Response to Bicuculline in a Genetic Absence Epilepsy Rat Model

et al. 2008

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Abstract. The posterior part of the hypothalamus plays a vital role in the homeostatic processes of the internal environment, including blood pressure and heart rate regulation, by means of γ-aminobutyric acid (GABA)ergic and glutamatergic neurotransmission. In this study we measured the extracellular levels of GABA and L-glutamic acid in the dorsomedial hypothalamic nucleus (DMH) and posterior hypothalamus (PH), following intracerebroventricular (i.c.v.) administration of bicuculline, a GABA A -receptor antagonist, in genetic absence epileptic rats from Strasbourg (GAERS), where heart rate, blood pressure, and EEG recordings were also collected simultaneously. The i.c.v. injection of bicuculline (0.3 nmol) produced no response in nonepileptic Wistar rats but caused an increase in mean arterial pressure in GAERS (P<0.01). Microdialysis experiments showed that L-glutamic acid increased in the DMH in GAERS after bicuculline administration (P<0.01). Additionally, extracellular GABA concentration decreased in the PH (P<0.05). Bicuculline suppressed the spike-and-wave discharges, the characteristic sign of absence seizures. All these results suggest that the bicuculline-induced blood pressure response is accompanied by changes in L-glutamic acid levels in the DMH and GABA levels in the PH, indicating a bicuculline hypersensitivity in the DMH and PH of GAERS that may make the GAERS display an altered mode of central cardiovascular regulation. These results suggest that the circuits affected in GAERS are not only restricted to the regions responsible for seizure generation but also present in the hypothalamus.

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“…Previous studies demonstrated that disruption of GABAergic neurotransmission in the dorsomedial nucleus evokes increases in arterial blood pressure, heart rate, peripheral sympathetic nerve activity and plasma catecholamine levels in both conscious and anesthetized rats, suggesting that the GABAergic system in the dorsomedial nucleus exerts a tonic inhibitory influence over the sympathetic nervous system [15][16][17]. Moreover, we demonstrated that the activation of N-methyl-D-aspartate (NMDA) receptors in the dorsomedial nucleus evokes significant increases in blood pressure and heart rate [18]. These results provide evidence for the involvement of dorsomedial nucleus in the central regulation of cardiovascular functions.…”

Section: Introductionmentioning

confidence: 74%

“…Our previous experiments demonstrated the roles of GABA A -mediated inhibitory and NMDA-mediated excitatory mechanisms in the modulation of cardiovascular functions [16,18]. Limbic structures such as amygdala and hippocampus are richly interconnected with hypothalamic regions.…”

Section: Discussionmentioning

confidence: 95%

Extracellular Concentrations of Catecholamines and Amino Acids in the Dorsomedial Hypothalamus of Kindled Rats

Gören

Aker²,

Yananlı³

et al. 2003

Pharmacology

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Epilepsy affects homeostasis and autonomic nervous system functions. It has been thought that the dysfunction in the autonomic neural mechanisms could be a cause of sudden unexpected death in patients with epilepsy. The kindling model of epilepsy is considered to be an animal model for complex partial seizures with secondary generalization. The objectives of this study were to investigate the extracellular γ-aminobutyric acid (GABA), glutamate, noradrenaline and dopamine levels in the dorsomedial nucleus of the hypothalamus in non-epileptic and kindled epileptic rats and to explain some of the cardiovascular changes in the kindling model of epilepsy. Stimulation electrodes were stereotaxically implanted into the basolateral amygdala and electrical stimulation was applied 3 times a day at a constant current. The rats were then kindled to full stage 5 seizures. Microdialysis experiments were performed to demonstrate the neurotransmitter levels in the dorsomedial nucleus of the hypothalamus 3–5 days after being kindled. Decreases in noradrenaline and dopamine levels in the dorsomedial nucleus were detected in the conscious kindled animals. This finding is in agreement with prior findings that the noradrenergic system has a negative role in the process of kindling. The basal level of glutamic acid and GABA remained unchanged in the kindled group when compared to non-epileptic animals, and similarly, neither blood pressure nor heart rate responses to bicuculline or N-methyl-D-aspartate were affected by the acute kindled state. These findings suggest that the autonomic changes in kindling require further studies.

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Cardiovascular Responses to NMDA Injected into Nuclei of Hypothalamus or Amygdala in Conscious Rats

Cited by 13 publications

References 33 publications

Increase in Blood Pressure by Local Injection of Ketamine into the Amygdala in Rats

Increase in Blood Pressure by Local Injection of Ketamine into the Amygdala in Rats

Extracellular Hypothalamic γ-Aminobutyric Acid (GABA) and L-Glutamic Acid Concentrations in Response to Bicuculline in a Genetic Absence Epilepsy Rat Model

Extracellular Concentrations of Catecholamines and Amino Acids in the Dorsomedial Hypothalamus of Kindled Rats

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