Responses of Raphe Nucleus Projecting Subfornical Organ Neurons to Angiotensin II in Rats

Tanaka, Junichi; Ushigome, Akihiko; Hori, Koji; Nomura, Masahiko

doi:10.1016/s0361-9230(97)00371-7

Cited by 23 publications

(13 citation statements)

References 13 publications

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“…Alternatively, other pertinent observations support the hypothesis that volume depletion (and possibly the serial changes in arterial pressure) activates neurons of the SFO sensitive to ANG II, which project to form synapses with serotonergic neurons of the DRN (7,30). As a result of this monitoring of the circulating levels of ANG II, signals would be generated and transmitted by ascending serotonergic pathways of the DRN with the objective of modulating sodium appetite, with subsequent regulation of extracellular fluid volume.…”

Section: Discussionmentioning

confidence: 85%

“…As mentioned previously, these structures are innervated by serotonergic neurons, are rich in serotonin receptors and reciprocally transmit signals to the raphe (1,2,4-6,8). It is quite likely that these signals reflect adjustments concerning variations in volume, electrolytic composition of the extracellular fluid and cardiovascular parameters (4,5,7,30).…”

Section: Discussionmentioning

confidence: 99%

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Effect of electrolytic lesion of the dorsal raphe nucleus on water intake and sodium appetite

Olivares

Costa-e-Sousa

Cavalcante-Lima

et al. 2003

Braz J Med Biol Res

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The present study determined the effect of an electrolytic lesion of the dorsal raphe nucleus (DRN) on water intake and sodium appetite. Male Wistar rats weighing 290-320 g with a lesion of the DRN (L-DRN), performed two days before experiments and confirmed by histology at the end of the experiments, presented increased sensitivity to the dehydration induced by fluid deprivation. The cumulative water intake of L-DRN rats reached 23.3 ± 1.9 ml (a 79% increase, N = 9) while sham-lesioned rats (SL-DRN) did not exceed 13.0 ± 1.0 ml (N = 11, P < 0.0001) after 5 h. The L-DRN rats treated with isoproterenol (300 µg kg -1 ml -1 , sc) exhibited an increase in water intake that persisted throughout the experimental period (L-DRN, 15.7 ± 1.47 ml, N = 9 vs SL-DRN, 9.3 ± 1.8 ml, N = 11, P < 0.05). The L-DRN rats also showed an increased spontaneous sodium appetite during the entire period of assessment. The intake of 0.3 M NaCl after 12, 24, 36 and 72 h by the L-DRN rats was always higher than 20.2 ± 4.45 ml (N = 10), while the intake by SL-DRN was always lower than 2.45 ± 0.86 ml (N = 10, P < 0.00001). Sodium-and water-depleted L-DRN rats also exhibited an increased sodium appetite (13.9 ± 2.0 ml, N = 11) compared to SL-DRN (4.6 ± 0.64 ml, N = 11) after 120 min of observation (P < 0.02). The sodium preference of L-DRN rats in both conditions was always higher than that of SL-DRN rats. These results suggest that electrolytic lesion of the DRN overcomes a tonic inhibitory component of sodium appetite. Correspondence

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Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Effect of electrolytic lesion of the dorsal raphe nucleus on water intake and sodium appetite

Olivares

Costa-e-Sousa

Cavalcante-Lima

et al. 2003

Braz J Med Biol Res

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“…Furthermore, the ubiquitous distribution of terminals and the diversity of forebrain 5-HT receptors has allowed to elaborate the hypothesis that 5-HTergic system would interfere practically in all of the integrative mechanisms of neuronal plasticity, in nature, autonomic, neuroendocrine, behavioral and cognitive (Azmitia and Segal 1978, Azmitia 1987, Jacobs and Azmitia 1992 Forebrain structures involved with the hydroelectrolyte and cardiocirculatory control reciprocally innervate the midbrain raphe (Lind 1986, Tanaka et al 1998, Celada et al 2002. Contingent of ANG II-sensitive neurons from SFO project toward 5-HTergic neurons of DRN (Tanaka et al 1998). This assessment was carried out in study in which neurons of DRN, antidromically identifi ed, were excited by intra-carotid or iontophoretic administration of ANG II into SFO.…”

Section: Regulationmentioning

confidence: 99%

Role of the serotoninergic system in the sodium appetite control

Reis

2007

An. Acad. Bras. Ciênc.

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The present article reviews the role of the serotoninergic system in the regulation of the sodium appetite. Data from the peripheral and icv administration of serotoninergic (5-HTergic) agents showed the participation of 5-HT2/3 receptors in the modulation of sodium appetite. These observations were extended with the studies carried out after brain serotonin depletion, lesions of DRN and during blockade of 5-HT2A/2C receptors in lateral parabrachial nucleus (LPBN). Brain serotonin depletion and lesions of DRN increased the sodium appetite response, in basal conditions, after sodium depletion and hypovolemia or after beta-adrenergic stimulation as well. These observations raised the hypothesis that the suppression of ascending pathways from the DRN, possibly, 5-HTergic fi bers, modifi es the angiotensinergic or sodium sensing mechanisms of the subfornical organ involved in the control of the sodium appetite. 5-HTergic blockade in LPBN induced to similar results, particularly those regarded to the natriorexigenic response evoked by volume depletion or increase of the hypertonic saline ingestion induced by brain angiotensinergic stimulation. In conclusion, many evidences lead to acceptation of an integrated participation resulting of an interaction, between DRN and LPBN, for the sodium appetite control.

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“…There is a reciprocal connection linking DRN and SFO (7)(8)(9) which suggests that the DRN participates in cardiovascular as well as in extracellular fluid (ECF) volume and electrolyte homeostasis. Angiotensinergic stimulation of the SFO elicits electrophysiological alterations in DRN serotonergic neurons (9). On the other hand, isosmotic hypovolemia induced by hemorrhage evokes changes in the electrical activity of DRN serotonergic neurons connected with the SFO (10).…”

Section: Introductionmentioning

confidence: 99%

“…DRN afferent fibers arise from these areas (especially the SFO), probably involved in a feedback loop regulating sodium satiety and contributing to ECF volume and cardiocirculatory homeostasis (7,9,21).…”

Section: Introductionmentioning

confidence: 99%

Chronic excitotoxic lesion of the dorsal raphe nucleus induces sodium appetite

Cavalcante-Lima

Badauê‐Passos

de-Lucca

et al. 2005

Braz J Med Biol Res

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We determined if the dorsal raphe nucleus (DRN) exerts tonic control of basal and stimulated sodium and water intake. Male Wistar rats weighing 300-350 g were microinjected with phosphate buffer (PB-DRN, N = 11) or 1 µg/0.2 µl, in a single dose, ibotenic acid (IBO-DRN, N = 9 to 10) through a guide cannula into the DRN and were observed for 21 days in order to measure basal sodium appetite and water intake and in the following situations: furosemide-induced sodium depletion (20 mg/kg, sc, 24 h before the experiment) and a low dose of dietary captopril (1 mg/g chow). From the 6th day after ibotenic acid injection IBO-DRN rats showed an increase in sodium appetite (12.0 ± 2.3 to 22.3 ± 4.6 ml 0.3 M NaCl intake) whereas PB-DRN did not exceed 2 ml (P < 0.001). Water intake was comparable in both groups. In addition to a higher dipsogenic response, sodium-depleted IBO-DRN animals displayed an increase of 0.3 M NaCl intake compared to PB-DRN (37.4 ± 3.8 vs 21.6 ± 3.9 ml 300 min after fluid offer, P < 0.001). Captopril added to chow caused an increase of 0.3 M NaCl intake during the first 2 days (IBO-DRN, 33.8 ± 4.3 and 32.5 ± 3.4 ml on day 1 and day 2, respectively, vs 20.2 ± 2.8 ml on day 0, P < 0.001). These data support the view that DRN, probably via ascending serotonergic system, tonically modulates sodium appetite under basal and sodium depletion conditions and/or after an increase in peripheral or brain angiotensin II.

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Responses of Raphe Nucleus Projecting Subfornical Organ Neurons to Angiotensin II in Rats

Cited by 23 publications

References 13 publications

Effect of electrolytic lesion of the dorsal raphe nucleus on water intake and sodium appetite

Effect of electrolytic lesion of the dorsal raphe nucleus on water intake and sodium appetite

Role of the serotoninergic system in the sodium appetite control

Chronic excitotoxic lesion of the dorsal raphe nucleus induces sodium appetite

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