The medial amygdaloid area is involved in activation of angiotensin II-sensitive neurons in the anterior hypothalamic area

Hagiwara, Yukihiko; Nishigori, Yusuke; Fukumori, Ryuji; Kubo, Takao

doi:10.1016/j.brainres.2004.11.015

Cited by 13 publications

(2 citation statements)

References 34 publications

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“…The medial amygdala has one of the highest densities of angiotensinogen mRNA 43 and angiotensin microinjected into the medial amygdala inhibits sexual behaviour in rats 44 . Glutamate stimulation of neurons in the medial amygdala releases angiotensin in the anterior hypothalamus, 45 a region identified as innervating the PVN 46 . Thus, angiotensin, via AT 1 receptors, may be an inhibitory neuromodulator within the medial amygdala.…”

Section: Angiotensin and The Medial Amygdalamentioning

confidence: 99%

Role of the medial amygdala in mediating responses to aversive stimuli leading to hypertension

Davern

Head

2011

Clin Exp Pharma Physio

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1. The amygdala is a part of the limbic system that is associated with mediating the emotional and hormonal response to stress and although studies have focused on the central amygdala, there is increasing evidence that the medial amygdala is a major region activated by stressful stimuli. 2. Neuroanatomical studies in rats have shown greater activation in the medial amygdala following aversive stresses compared with other brain regions, including the central amygdala. Inhibition of the medial, but not the central, amygdala attenuates the development of hypertension in spontaneously hypertensive rats. 3. Schlager (BPH/2J) mice have a neurogenic form of hypertension that is most evident during the night when the mice are most active and is closely correlated with the level of activation of neurons in the medial, but not the central, amygdala. Pressor responses to aversive stimuli, such as restraint and cage-switch stress, are much greater in BPH/2J hypertensive than BPN/3J normotensive mice, but appetitive arousal produces normal increases in blood pressure. The degree of activation in the medial amygdala in BPH/2J hypertensive mice during aversive stress closely correlates with the increased blood pressure. 4. Thus, the inappropriate activation of the medial amygdala evoked by specific fear or aversive stimuli may be key to the neurogenic hypertension.

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Section: Angiotensin and The Medial Amygdalamentioning

confidence: 99%

Role of the medial amygdala in mediating responses to aversive stimuli leading to hypertension

Davern

Head

2011

Clin Exp Pharma Physio

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“…Fukumori et al (2004) showed that ibotenic acid lesion of the MeA mitigates the development of hypertension in spontaneously hypertensive rats. Additionally, microinjections of glutamate into the MeA evoked tonic firing of angiotensin II-sensitive neurones in the anterior hypothalamic area, important for the development of hypertension (Hagiwara et al, 2005). These findings have been interpreted as evidence of the medial amygdala playing a role in the engagement of physiological responses during the processing of sociosexual behaviours, fear conditioning and stress responses (Takahashi et al, 2007;Davern and Head, 2011).…”

Section: Implications Of Amygdala Involvement In Autonomic Functionsmentioning

confidence: 95%

Limbic modulation of the autonomic nervous system

Ajayi¹

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Nuclei in the hypothalamus and brainstem are responsible for maintaining homoeostasis by controlling rhythmic motor and autonomic activities. However, during emotional responses to real or potential environmental challenges, significant changes in motor and autonomic rhythm also occur.Forebrain structures that form the limbic system are responsible for perceiving environmental challenges and orchestrating appropriate emotional responses. Thus, it is only through descending synaptic interactions of the forebrain areas with the hypothalamus and brainstem, that modulation of motor and autonomic activities is possible during the expression of emotions. However, there is little knowledge of the forebrain areas that modulate autonomic activities. Also, in coordinating physiologic responses, forebrain structures operate through functional networks but the neural pathways and mechanisms involved particularly during emotional behaviours are not clear.The hippocampus is an important component of the limbic system involved in learning and memory, but evolving evidence implicates it in the expression of emotions such as defensive fear and anxiety reactions. Studies also suggest possible hippocampal connections with brainstem autonomic centres.Thus, the central hypothesis tested in this thesis is that discrete neurone populations in the ventral hippocampus, via neuronal projections to the amygdala, can modulate bulbar motor and autonomic output. Specific aims were to 1) Investigate and describe the respiratory and cardiovascular changes induced by chemically mapping the dorsal and ventral hippocampus with microinjections of the excitatory amino acid, D, L-Homocysteic acid, 2) Investigate the distribution of descending projections of the hippocampus using classical neuroanatomical tract tracing techniques, with a particular focus on the connectivity of the ventral hippocampus and the amygdala, 3) To extend the chemical mapping to specific areas in the amygdala that receive projections from the hippocampus and determine how such areas differ in their influence over motor and autonomic functions and 4) To investigate the effects of inhibiting of the amygdala while stimulating the ventral hippocampus.Experiments were conducted using urethane-anaesthetised (1.5 g/kg IP) adult Sprague-Dawley rats (n = 136; weight = 300 -600 g; either sex). The hippocampus was stereotaxically mapped to locate discrete neurone populations that can modulate motor and autonomic activities. The specific parameters monitored include blood pressure, heart rate, respiratory frequency, inspiratory and expiratory durations, tracheal pressure and the motor expression of augmented breaths.Microinjections of the excitatory amino acid (EAA), D, L, Homocysteic acid (DLH; 50 mM, pH 7.4, iii n = 95), were used for chemical stimulation. Using this stimulation technique, discrete neurone populations in the ventral hippocampus were identified that can generate significant changes in both respiratory and cardiovascular parameters. Augmented breaths, which have...

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Central injection of hypertonic saline activates angiotensin II-sensitive neurons in the anterior hypothalamic area of rats

et al. 2005

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The medial amygdaloid area is involved in activation of angiotensin II-sensitive neurons in the anterior hypothalamic area

Cited by 13 publications

References 34 publications

Role of the medial amygdala in mediating responses to aversive stimuli leading to hypertension

Role of the medial amygdala in mediating responses to aversive stimuli leading to hypertension

Limbic modulation of the autonomic nervous system

Central injection of hypertonic saline activates angiotensin II-sensitive neurons in the anterior hypothalamic area of rats

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