Fine structural evidence of degeneration in supraoptic nucleus and subfornical organ of rats with lesions in the anteroventral third ventricle

Carithers, Jeanine; Bealer, Steven L.; Brody, Michael J.; Johnson, Alan Kim

doi:10.1016/0006-8993(80)90770-2

Cited by 56 publications

(24 citation statements)

References 20 publications

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“…The horseradish peroxidase technique has been applied to sheep and revealed a prominant projection from the nucleus medianus to the SON with less dense projections from the SFO and OVLT (Miselis, McKinley, Simpson, Leventer & Denton, 1984 histological and electrophysiological studies. Degenerating axon terminals appeared in the SON, and signs of retrograde degeneration in the SFO after AV3V lesions in rats (Carithers et al 1980). After water deprivation in rats with lesions, the ultrastructural and immunocytochemical changes in the hypothalamo-neurohypophysial system which are characteristic of increased vasopressin secretion were absent.…”

Section: Circumventricular Organsmentioning

confidence: 93%

Control of Release of Vasopressin by Neuroendocrine Reflexes

1988

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Section: Circumventricular Organsmentioning

confidence: 93%

Control of Release of Vasopressin by Neuroendocrine Reflexes

1988

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“…After the MnPO, the OVLT followed by the SON appear to be the next nuclei, respectively, receiving the highest number of efferent projections from the SFO (94). In the SON, it is primarily the magnocellular (i.e., vasopressinergic) neurons that receive SFO input (13,93,133); and injection of a retrograde tracer into the SON demonstrated that it is mainly the peripheral portion of the SFO that projects to the SON (64). The connection of the SFO to the magnocellular PVN (mPVN) has also been demonstrated by an injection of the neuronal tracer, biotinylated dextran amine (BDA), into the peripheral portion of the SFO (68).…”

Section: Subfornical Organ: Anatomy Connections and Physiological Fmentioning

confidence: 99%

Mechanisms of brain renin angiotensin system-induced drinking and blood pressure: importance of the subfornical organ

Coble¹,

Grobe

Johnson³

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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Coble JP, Grobe JL, Johnson AK, Sigmund CD. Mechanisms of brain renin angiotensin system-induced drinking and blood pressure: importance of the subfornical organ. Am J Physiol Regul Integr Comp Physiol 308: R238 -R249, 2015. First published December 17, 2014 doi:10.1152/ajpregu.00486.2014.-It is critical for cells to maintain a homeostatic balance of water and electrolytes because disturbances can disrupt cellular function, which can lead to profound effects on the physiology of an organism. Dehydration can be classified as either intra-or extracellular, and different mechanisms have developed to restore homeostasis in response to each. Whereas the renin-angiotensin system (RAS) is important for restoring homeostasis after dehydration, the pathways mediating the responses to intra-and extracellular dehydration may differ. Thirst responses mediated through the angiotensin type 1 receptor (AT 1R) and angiotensin type 2 receptors (AT 2R) respond to extracellular dehydration and intracellular dehydration, respectively. Intracellular signaling factors, such as protein kinase C (PKC), reactive oxygen species (ROS), and the mitogen-activated protein (MAP) kinase pathway, mediate the effects of central angiotensin II (ANG II). Experimental evidence also demonstrates the importance of the subfornical organ (SFO) in mediating some of the fluid intake effects of central ANG II. The purpose of this review is to highlight the importance of the SFO in mediating fluid intake responses to dehydration and ANG II.angiotensin; blood pressure; barin; fluid; renin FLUID BALANCE is crucial for the homeostasis and survival of organisms because they have to properly maintain fluid and electrolyte concentrations for the normal function of all cells. Fluid balance can go awry in pathological states such as in chronic kidney disease and diabetes. Among its many roles in maintaining homeostasis, the renin-angiotensin system (RAS) is an important regulator of fluid balance. The RAS achieves this through the actions of its main effector peptide, angiotensin II (ANG II) through the ANG II type 1 (AT 1 R) and type 2 (AT 2 R) receptors. Activation of AT 1 R by blood-borne ANG II in target tissues causes increases in sodium and water retention, arginine vasopressin (AVP), and aldosterone release, vasoconstriction, increased sympathetic nervous system activity, and increased fluid intake. ANG II is produced by the consecutive enzymatic action of renin on its substrate angiotensinogen (AGT) and by angiotensin-converting enzyme (ACE) on its substrate angiotensin I (ANG I). The renin-AGT cleavage step is generally the rate-limiting step in the production of ANG II, and this is certainly true in the brain where the amount of renin is limiting. The RAS exists in two forms: a circulatory form where ANG II acts as an endocrine factor, and a tissue-specific form, where local production of ANG II acts in an autocrine or paracrine manner to induce AT 1 R signaling on ANG II producing or nearby cells (75). Intracrine, or intracellular forms of the RAS, hav...

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“…Efferent projections to the MnPO from the SFO have been implicated in osmoreception, and although AV3V lesions do not destroy SFO, many efferents from the SFO are disrupted. For example, following AV3V lesions, anterograde degeneration was observed in SON and PVN, and retrograde degeneration was observed in SFO (16,17). AV3V lesions destroy connections between the MnPO and MPO and therefore indirect SFO projections to MPO.…”

Section: Sites For Integration Of Temperature and Fluid Homeostasismentioning

confidence: 99%

Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels

Sladek

Johnson

2013

American Journal of Physiology-Regulatory, Integrative and Comp

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Sladek CD, Johnson AK. Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels. Am J Physiol Regul Integr Comp Physiol 305: R669 -R678, 2013. First published July 24, 2013 doi:10.1152/ajpregu.00270.2013.-Maintenance of body water homeostasis is critical for preventing hyperthermia, because evaporative cooling is the most efficient means of dissipating excess body heat. Water homeostasis is achieved by regulation of water intake and water loss by the kidneys. The former is achieved by sensations of thirst that motivate water acquisition, whereas the latter is regulated by the antidiuretic action of vasopressin. Vasopressin secretion and thirst are stimulated by increases in the osmolality of the extracellular fluid as well as decreases in blood pressure and/or blood volume, signals that are precipitated by water depletion associated with the excess evaporative water loss required to prevent hyperthermia. In addition, they are stimulated by increases in body temperature. The sites and molecular mechanisms involved in integrating thermal and osmotic regulation of thirst and vasopressin secretion are reviewed here with a focus on the role of the thermal and mechanosensitive transient receptor potential-vanilloid (TRPV) family of ion channels. thirst; TRPV; vasopressin; hypothalamus MAINTENANCE of a constant body temperature by homeotherms is critically dependent on body water homeostasis, because evaporative cooling is the most efficient means that homeotherms have for dissipating excess body heat. Even at rest, heat is generated as a by-product of basal cellular metabolism and the ongoing muscle activity of the heart beating, respiration, and gastrointestinal motility. For a typical 70-kg man the resting (basal) rate of metabolic heat production is about 80 kcal/h, but intense exercise can increase heat production to 400 -600 kcal/h. Thus the body must have efficient mechanisms for dissipating heat to prevent hyperthermia. In humans, body heat is dissipated by passive transfer of heat from the skin to the air. The heat generated by muscles and internal organs is transferred to the skin by the blood flowing through epidermal capillaries. Thus heat loss can be increased by increasing skin blood flow and by increasing the movement of air next to the skin by removing clothing and standing near a fan or in a breeze. However, evaporative cooling significantly augments heat loss from the skin, because evaporation of 1 gram of water from the skin dissipates 0.6 kcal. Thus a sweat rate of 1 l/h could theoretically remove 600 kcal/h from the body. Furcovered mammals also rely heavily on evaporative cooling for maintaining body temperature with increased body temperature promoting panting, increased salivation, and saliva spreading in dogs, cats, and rats. However, water loss of the magnitude required in many instances to adequately dissipate excess body heat must be compensated to prevent electrolyte imbalance and preserve blood volume for adequate cardiovascular function. Thus mechanis...

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Fine structural evidence of degeneration in supraoptic nucleus and subfornical organ of rats with lesions in the anteroventral third ventricle

Cited by 56 publications

References 20 publications

Control of Release of Vasopressin by Neuroendocrine Reflexes

Control of Release of Vasopressin by Neuroendocrine Reflexes

Mechanisms of brain renin angiotensin system-induced drinking and blood pressure: importance of the subfornical organ

Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels

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