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Amino acids that centrally influence blood pressure and regional blood flow in conscious rats.

Takemoto Y - J Amino Acids (2012)

Bottom Line: This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow.Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements.Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurophysiology, Graduate School Biomedical Sciences, Hiroshima University, Kasumi-cho 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.

ABSTRACT
Functional roles of amino acids have increasingly become the focus of research. This paper summarizes amino acids that influence cardiovascular system via the brain of conscious rats. This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow. This section includes a concise history of amino acid neurotransmitters in cardiovascular research and summarizes brain areas where chemical stimulations produce blood pressure changes mainly in anesthetized animals. This is followed by comments about findings regarding several newly examined amino acids with intracisternal stimulation in conscious rats that produce changes in blood pressure. The same pressor or depressor response to central amino acid stimulations can be produced by distinct mechanisms at central and peripheral levels, which will be briefly explained. Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements. Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows. They may have physiological roles in the healthy brain, but pathological roles in the brain with cerebral vascular diseases such as stroke where the blood-brain barrier is broken.

No MeSH data available.


Related in: MedlinePlus

Potential brain nuclei of which neurons respond to intracisternal injection of amino acid solution, in the sagittal view of the rat brain. SON, the supraoptic nucleus of the hypothalamus; NTS, the nucleus tractus solitarii; RVLM, rostral ventrolateral medulla; CVLM, caudal ventrolateral medulla; CPA, caudal pressor area. Gray area indicates the ventricular system from the third ventricle to the central canal in the spinal cord.
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fig5: Potential brain nuclei of which neurons respond to intracisternal injection of amino acid solution, in the sagittal view of the rat brain. SON, the supraoptic nucleus of the hypothalamus; NTS, the nucleus tractus solitarii; RVLM, rostral ventrolateral medulla; CVLM, caudal ventrolateral medulla; CPA, caudal pressor area. Gray area indicates the ventricular system from the third ventricle to the central canal in the spinal cord.

Mentions: There are several well-examined neuronal groups which change blood pressure at medulla level when chemically stimulated (Figure 5); rostral ventrolateral medulla (RVLM) [16, 45–49], caudal ventrolateral medulla (CVLM) [47, 50–56], and nucleus tractus solitarii (NTS) [57–64]. Neural pathways of a reflex which detects changes in blood pressure and returns it to the original level via mainly sympathetic neurons (called the baroreceptor reflex) include NTS, RVLM, and CVLM. Baroreceptor afferent neurons of vagal and glossopharyngeal nerves terminate second-order neurons in the NTS [65–67] that send information to GABAergic interneurons in the CVLM [68]. When baroreceptors in the aortic arch and carotid sinus detect an increase in blood pressure, excited GABAergic neurons in the CVLM inhibit presympathetic neurons in the RVLM, leading to a decrease in sympathetic activity and resulting in restoration of original blood pressure [21]. RVLM is believed to contain the most essential neuronal group to maintain the resting and tonic vasomotor sympathetic activity, since lesion or inhibition of RVLM produces severe hypotension equivalent to a spinal transection [50, 69] and blockade of many cardiovascular-related reflexes [12].


Amino acids that centrally influence blood pressure and regional blood flow in conscious rats.

Takemoto Y - J Amino Acids (2012)

Potential brain nuclei of which neurons respond to intracisternal injection of amino acid solution, in the sagittal view of the rat brain. SON, the supraoptic nucleus of the hypothalamus; NTS, the nucleus tractus solitarii; RVLM, rostral ventrolateral medulla; CVLM, caudal ventrolateral medulla; CPA, caudal pressor area. Gray area indicates the ventricular system from the third ventricle to the central canal in the spinal cord.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368589&req=5

fig5: Potential brain nuclei of which neurons respond to intracisternal injection of amino acid solution, in the sagittal view of the rat brain. SON, the supraoptic nucleus of the hypothalamus; NTS, the nucleus tractus solitarii; RVLM, rostral ventrolateral medulla; CVLM, caudal ventrolateral medulla; CPA, caudal pressor area. Gray area indicates the ventricular system from the third ventricle to the central canal in the spinal cord.
Mentions: There are several well-examined neuronal groups which change blood pressure at medulla level when chemically stimulated (Figure 5); rostral ventrolateral medulla (RVLM) [16, 45–49], caudal ventrolateral medulla (CVLM) [47, 50–56], and nucleus tractus solitarii (NTS) [57–64]. Neural pathways of a reflex which detects changes in blood pressure and returns it to the original level via mainly sympathetic neurons (called the baroreceptor reflex) include NTS, RVLM, and CVLM. Baroreceptor afferent neurons of vagal and glossopharyngeal nerves terminate second-order neurons in the NTS [65–67] that send information to GABAergic interneurons in the CVLM [68]. When baroreceptors in the aortic arch and carotid sinus detect an increase in blood pressure, excited GABAergic neurons in the CVLM inhibit presympathetic neurons in the RVLM, leading to a decrease in sympathetic activity and resulting in restoration of original blood pressure [21]. RVLM is believed to contain the most essential neuronal group to maintain the resting and tonic vasomotor sympathetic activity, since lesion or inhibition of RVLM produces severe hypotension equivalent to a spinal transection [50, 69] and blockade of many cardiovascular-related reflexes [12].

Bottom Line: This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow.Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements.Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurophysiology, Graduate School Biomedical Sciences, Hiroshima University, Kasumi-cho 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.

ABSTRACT
Functional roles of amino acids have increasingly become the focus of research. This paper summarizes amino acids that influence cardiovascular system via the brain of conscious rats. This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow. This section includes a concise history of amino acid neurotransmitters in cardiovascular research and summarizes brain areas where chemical stimulations produce blood pressure changes mainly in anesthetized animals. This is followed by comments about findings regarding several newly examined amino acids with intracisternal stimulation in conscious rats that produce changes in blood pressure. The same pressor or depressor response to central amino acid stimulations can be produced by distinct mechanisms at central and peripheral levels, which will be briefly explained. Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements. Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows. They may have physiological roles in the healthy brain, but pathological roles in the brain with cerebral vascular diseases such as stroke where the blood-brain barrier is broken.

No MeSH data available.


Related in: MedlinePlus