The role of angiotensin II in the central regulation of feed intake in sheep

Sunagawa, Katsunori; Weisinger, R. S.; Purcell, B.; Thomson, Craig; Burns, Peta

doi:10.4141/a00-055

Cited by 12 publications

(14 citation statements)

References 34 publications

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“…From these results, it is thought that to maintain a homeostasis in water and Na content of body fluid, the renin–angiotensin system was activated and vasopressin was released in P sheep (Ramsay & Ganong 1986). The intravenously injected vasopressin or ICV infused angiotensin II (AngII) decreased feed intake in sheep (Meyer et al 1989; Sunagawa et al. 2001).…”

Section: Discussionmentioning

confidence: 99%

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Effect of intracerebroventricular infusion of urocortin on feed and salt intake in parotid fistulated sheep

Sunagawa

Purcell

Thomson

et al. 2002

Animal Science Journal

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The effect of a new peptide, brain urocortin (UCN), in the central regulation of feed and salt intake in parotid fistulated sheep was investigated through a continuous intracerebroventricular (ICV) infusion of the peptide at a small dose for 48 h. Feed and salt intake on day 1 of UCN infusion were similar to those before infusion. However, feed and salt intake on day 2 during UCN infusion decreased significantly. Water intake on days 1 and 2 during UCN infusion was the same as that before infusion. Saliva secretion from the unilateral parotid gland during UCN infusion was unchanged from that before infusion. On the other hand, urine excretion during UCN infusion increased significantly. The present results suggested that UCN acts directly on the brain mechanisms of sheep to decrease feed and salt intake, but does not alter water intake.KEYWORDS: brain urocortin, feed intake, parotid fistulated sheep, salt intake. adrenal axis and the sympathetic nervous system (Antoni 1986;Menzaghi et al. 1993; Imai et al. 1995). In animals exposed to stress, corticotropin-releasing hormone (CRH) is released from the hypothalamus, adrenocorticotropic hormone (ACTH) is released from the pituitary gland, and cortisol is released from the adrenal gland. It is reported that CRH depresses feed intake in sheep (Sunagawa et al. 2000). However, the influence of the peptide on mineral intake is unclear.A new peptide, urocortin (UCN), was isolated from a discrete midbrain region in rats (Vaughan et al. 1995). The amino acid sequence of this peptide is related to urotensin (63% sequence identity) and CRH (45% sequence identity). Urocortin has similar biological activities to urotensin and CRH. Urocortin is more potent than CRH in binding and activating corticotropin-releasing factor R2 (CRF-R2) receptors (Vaughan et al. 1995).The aim of the present research was to determine the effect of brain UCN on feed and salt intake in parotid fistulated sheep.

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Section: Discussionmentioning

confidence: 99%

“…It is therefore thought that vasopressin and AngII depressed feeding in P sheep. In NP sheep with continuous access to water and 0.5 mol/L NaCl solution, ICV infused AngII caused an increase in salt intake (Sunagawa et al. 2001).…”

Section: Discussionmentioning

confidence: 99%

Effect of intracerebroventricular infusion of urocortin on feed and salt intake in parotid fistulated sheep

Sunagawa

Purcell

Thomson

et al. 2002

Animal Science Journal

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“…Decreases in feed intake during intracerebroventricular infusion of angiotensin II are caused by the production of thirst sensations in the brains of ewes leading to excessive water intake and ruminal distension (Sunagawa et al 2001). It was also reported that intraperitoneal injections of vasopressin decrease feed intake in goats (Meyer et al 1989).…”

Section: Plasma Glucose Concentrationmentioning

confidence: 99%

“…Parotid saliva secretion volumes in ruminants contribute 50 to 70% of the total mixed saliva secretion volumes (Tsuda et al 1994). Up to this point, Sunagawa et al (2001Sunagawa et al ( , 2005Sunagawa et al ( , 2007b have intravenously infused animals continuously with hypo-osmotic and iso-osomotic artificial saliva beginning 1 h prior to the commencement of feeding. Plasma osmolarities during infusion were comparatively low or equal to non-infusion values.…”

Section: Plasma Glucose Concentrationmentioning

confidence: 99%

An intravenous replenishment of salivary components decrease water intake and increases feed intake in freely drinking large-type goats fed on dry forage

Sunagawa¹,

Hashimoto²,

Izuno³

et al. 2008

Can. J. Anim. Sci.

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This research utilized two treatments to investigate if feed intake is reduced by changes in humoral factors induced by dry forage feeding in large-type goats given free access to water. In the control treatment (NI), a solution was not infused. The artificial parotid saliva i.v. infusion (ASI) treatment consisted of an i.v. infusion of artificial parotid saliva in order to replenish NaHCO3 and fluids lost from the blood to the rumen due to increased saliva secretion volume during initial stages of dry forage feeding. The ASI treatment significantly mitigated the decreases in circulating plasma volume caused by saliva secretion. Thirst was lower in the ASI-treated group, as indicated by the lower water intake (NI, 3894 mL 2 h-1; ASI, 3100 mL 2 h-1). Decreases with time in dry forage intake were significantly reduced by the ASI treatment (2134g 2 h-1) compared with the NI control (1756 g 2 h-1). These results indicate that under free drinking conditions, dry forage intake of large-type goats may likely be suppressed by the decrease in plasma volume and increase in water intake following saliva secretion during the initial stages of feeding. Key words: Dry forage intake, water intake, large-type goat

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“…The intravenous infusion of ANG II reduced parotid saliva secretion in ewes ( McKinley et al, 1979 ). Sunagawa et al (2001) reported that brain ANG II reduced dry forage intake in sheep. These facts indicate that the marked suppression of dry forage intake during the first hour was caused by a feeding-induced hypovolemia while the suppression of saliva secretion was brought about by the loss of NaHCO 3 from the blood due to increased saliva secretion during the initial stages of dry forage feeding.…”

Section: Introductionmentioning

confidence: 99%

The Physiological Suppressing Factors of Dry Forage Intake and the Cause of Water Intake Following Dry Forage Feeding in Goats — A Review

Sunagawa

Nagamine

2015

Asian Australas. J. Anim. Sci

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The goats raised in the barn are usually fed on fresh grass. As dry forage can be stored for long periods in large amounts, dry forage feeding makes it possible to feed large numbers of goats in barns. This review explains the physiological factors involved in suppressing dry forage intake and the cause of drinking following dry forage feeding. Ruminants consume an enormous amount of dry forage in a short time. Eating rates of dry forage rapidly decreased in the first 40 min of feeding and subsequently declined gradually to low states in the remaining time of the feeding period. Saliva in large-type goats is secreted in large volume during the first hour after the commencement of dry forage feeding. It was elucidated that the marked suppression of dry forage intake during the first hour was caused by a feeding-induced hypovolemia and the loss of NaHCO3 due to excessive salivation during the initial stages of dry forage feeding. On the other hand, it was indicated that the marked decrease in feed intake observed in the second hour of the 2 h feeding period was related to ruminal distension caused by the feed consumed and the copious amount of saliva secreted during dry forage feeding. In addition, results indicate that the marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding. After 40 min of the 2 h dry forage feeding period, the feed salt content is absorbed into the rumen and plasma osmolality increases. The combined effects of ruminal distension and increased plasma osmolality accounted for 77.6% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality are the main physiological factors in suppression of dry forage intake in large-type goats. There was very little drinking behavior observed during the first hour of the 2 h feeding period most water consumption occurring in the second hour. The cause of this thirst sensation during the second hour of dry forage feeding period was not hypovolemia brought about by excessive salivation, but rather increases in plasma osmolality due to the ruminal absorption of salt from the consumed feed. This suggests the water intake following dry forage feeding is determined by the level of salt content in the feed.

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The role of angiotensin II in the central regulation of feed intake in sheep

Cited by 12 publications

References 34 publications

Effect of intracerebroventricular infusion of urocortin on feed and salt intake in parotid fistulated sheep

Effect of intracerebroventricular infusion of urocortin on feed and salt intake in parotid fistulated sheep

An intravenous replenishment of salivary components decrease water intake and increases feed intake in freely drinking large-type goats fed on dry forage

The Physiological Suppressing Factors of Dry Forage Intake and the Cause of Water Intake Following Dry Forage Feeding in Goats — A Review

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