The subfornical organ and organum vasculosum of the lamina terminalis: Critical roles in cardiovascular regulation and the control of fluid balance

Fry, Mark; Ferguson, Alastair V.

doi:10.1016/b978-0-12-820107-7.00013-6

Cited by 7 publications

(5 citation statements)

References 96 publications

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“…These various mechanisms by which fructose can increase osmolality may also explain why this sugar induces vasopressin more significantly than glucose [23]. Osmoreceptors detect changes in serum osmolarity rapidly due to their location outside the blood-brain barrier, thus, we observed a very robust response to small osmolarity alterations in this study [24][25][26][27]. Increased serum osmolarity causes an acute stress response via several mechanisms, including the direct effect of vasopressin, secondary activation of RAS, activation of the sympathetic nervous system, and increased synthesis of ACTH which explains the findings of this study [28].…”

Section: Discussionmentioning

confidence: 54%

A study on the early metabolic effects of salt and fructose consumption: the protective role of water

Hasbal,

Bakir,

Incir

et al. 2024

Hypertens Res

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Increasing serum osmolality has recently been linked with acute stress responses, which over time can lead to increased risk for obesity, hypertension, and other chronic diseases. Salt and fructose are two major stimuli that can induce acute changes in serum osmolality. Here we investigate the early metabolic effects of sodium and fructose consumption and determine whether the effects of sodium or fructose loading can be mitigated by blocking the change in osmolality with hydration. Forty-four healthy subjects without disease and medication were recruited into four groups. After overnight fasting, subjects in Group 1 drank 500 mL of salty soup, while those in Group 2 drank 500 mL of soup without salt for 15 min. Subjects in Group 3 drank 500 mL of 100% apple juice in 5 min, while subjects in Group 4 drank 500 mL of 100% apple juice and 500 mL of water in 5 min. Blood pressure (BP), plasma sodium, and glucose levels were measured every 15 min in the first 2 h. Serum and urine osmolarity, serum uric acid, cortisol, fibroblast growth factor 21 (FGF21), aldosterone, adrenocorticotropic hormone (ACTH) level, and plasma renin activity (PRA) were measured at the baseline and 2 h. Both acute intake of salt or fructose increased serum osmolality (maximum ∼4 mOsm/L peaking at 75 min) associated with a rise in systolic and diastolic BP, PRA, aldosterone, ACTH, cortisol, plasma glucose, uric acid, and FGF21. Salt tended to cause greater activation of the renin-angiotensin-system (RAS), while fructose caused a greater rise in glucose and FGF21. In both cases, hydration could prevent the osmolality and largely block the acute stress response. Acute changes in serum osmolality can induce remarkable activation of the ACTH-cortisol, RAS, glucose metabolism, and uric acid axis that is responsive to hydration. In addition to classic dehydration, salt, and fructose-containing sugars can activate these responses. Staying well hydrated may provide benefits despite exposure to sugar and salt. More studies are needed to investigate whether hydration can block the chronic effects of sugar and salt on disease.

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Section: Discussionmentioning

confidence: 54%

A study on the early metabolic effects of salt and fructose consumption: the protective role of water

Hasbal,

Bakir,

Incir

et al. 2024

Hypertens Res

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“…The SCN is a hypothalamic nucleus known as the brain's circadian clock: it is found in all vertebrates that have been studied 67 . The OVLT is a sensory CVO with fenestrated blood vessels, and it is best known for its role in regulating thirst and water balance, among other functions 68–70 . The local connections between blood vessels of the SCN‐OVLT, similar to those of the pituitary portal pathway, enable small amounts of neurosecretions to reach their specialized targets in high concentrations without dilution in the general circulatory system.…”

Section: The Scn‐ovlt Connection: Identification Of a Second Portal P...mentioning

confidence: 99%

“…67 The OVLT is a sensory CVO with fenestrated blood vessels, and it is best known for its role in regulating thirst and water balance, among other functions. [68][69][70] The local connections between blood vessels of the SCN-OVLT, similar to those of the pituitary portal pathway, enable small amounts of neurosecretions to reach their specialized targets in high concentrations without dilution in the general circulatory system. Although the anatomical work reported to date did not establish the direction of blood flow, we conjectured that blood flows from the SCN to the OVLT based on a host of prior studies and on our substantial knowledge of the SCN 4 (Figure 4).…”

Section: Literature Reviewsmentioning

confidence: 99%

Parallel trajectories in the discovery of the SCN‐OVLT and pituitary portal pathways: Legacies of Geoffrey Harris

Silver

Yao

Roy

et al. 2023

J Neuroendocrinology

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A map of central nervous system organization based on vascular networks provides a layer of organization distinct from familiar neural networks or connectomes. As a well‐established example, the capillary networks of the pituitary portal system enable a route for small amounts of neurochemical signals to reach local targets by traveling along specialized pathways, thereby avoiding dilution in the systemic circulation. The first evidence of such a pathway in the brain came from anatomical studies identifying a portal pathway linking the hypothalamus and the pituitary gland. Almost a century later, we demonstrated a vascular portal pathway that joined the capillary beds of the suprachiasmatic nucleus and a circumventricular organ, the organum vasculosum of the lamina terminalis, in a mouse brain. For each of these portal pathways, the anatomical findings opened many new lines of inquiry, including the determination of the direction of flow of information, the identity of the signal that flowed along this pathway, and the function of the signals that linked the two regions. Here, we review landmark steps to these discoveries and highlight the experiments that reveal the significance of portal pathways and more generally, the implications of morphologically distinct nuclei sharing capillary beds.

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“…The SFO has been identified as the structure of the laminae terminalis ( Fry and Ferguson, 2021 ), and it is also involved in the regulation of osmotic pressure and thirst ( Noda and Hiyama, 2015 ). By immunohistochemistry, Na x channels were found to be on the SFO, which is the structural basis for the SFO to monitor changes in cerebrospinal fluid osmolality ( Noda and Hiyama, 2005 ).…”

Section: Introductionmentioning

confidence: 99%

The organum vasculosum of the lamina terminalis and subfornical organ: regulation of thirst

Wang,

Lv,

Yin

et al. 2023

Front. Neurosci.

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Thirst and water intake are regulated by the organum vasculosum of the lamina terminalis (OVLT) and subfornical organ (SFO), located around the anteroventral third ventricle, which plays a critical role in sensing dynamic changes in sodium and water balance in body fluids. Meanwhile, neural circuits involved in thirst regulation and intracellular mechanisms underlying the osmosensitive function of OVLT and SFO are reviewed. Having specific Nax channels in the glial cells and other channels (such as TRPV1 and TRPV4), the OVLT and SFO detect the increased Na+ concentration or hyperosmolality to orchestrate osmotic stimuli to the insular and cingulate cortex to evoke thirst. Meanwhile, the osmotic stimuli are relayed to the supraoptic nucleus (SON) and paraventricular nucleus of the hypothalamus (PVN) via direct neural projections or the median preoptic nucleus (MnPO) to promote the secretion of vasopressin which plays a vital role in the regulation of body fluid homeostasis. Importantly, the vital role of OVLT in sleep-arousal regulation is discussed, where vasopressin is proposed as the mediator in the regulation when OVLT senses osmotic stimuli.

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The subfornical organ and organum vasculosum of the lamina terminalis: Critical roles in cardiovascular regulation and the control of fluid balance

Cited by 7 publications

References 96 publications

A study on the early metabolic effects of salt and fructose consumption: the protective role of water

A study on the early metabolic effects of salt and fructose consumption: the protective role of water

Parallel trajectories in the discovery of the SCN‐OVLT and pituitary portal pathways: Legacies of Geoffrey Harris

The organum vasculosum of the lamina terminalis and subfornical organ: regulation of thirst

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