Functional identification of central pressor pathways originating in the subfornical organ

1991 ◽  
Vol 69 (7) ◽  
pp. 1035-1045 ◽  
Author(s):  
John Ciriello ◽  
Michael B. Gutman
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Paraventricular Nucleus ◽  
Supraoptic Nucleus ◽  
Subfornical Organ ◽  
Preoptic Nucleus ◽  
Thoracic Spinal Cord ◽  
Median Preoptic Nucleus ◽  
Pressor Responses ◽  
Stimulation Of

The functional projections from pressor sites in the subfornical organ (SFO) were identified using the 2-deoxyglucose (2-DG) autoradiographic method in urethane-anesthetized, sinoaortic-denervated rats. Autoradiographs of brain and spinal cord sections taken from rats whose SFO was continuously stimulated electrically for 45 min with stereotaxically placed monopolar electrodes (150 μA, 1.5-ms pulse duration, 15 Hz) following injection of tritiated 2-DG were compared with control rats that received intravenous infusions of pressor doses of phenylephrine to mimic the increase in arterial pressure observed during SFO stimulation. Comparisons were also made to autoradiographs from rats in which the ventral fornical commissure (CFV), just dorsal to the SFO, was electrically stimulated. The pressor responses during either electrical stimulation of the SFO or intravenous infusion of phenylephrine were similar in magnitude. On the other hand, stimulation of the CFV did not elicit a significant pressor response. Electrical stimulation of the SFO increased 2-DG uptake, in comparison to the phenylephrine-infused rats, in the nucleus triangularis, septofimbrial nucleus, lateral septal nucleus, nucleus accumbens, bed nucleus of the stria terminalis, dorsal and ventral nucleus medianus (median preoptic nucleus), paraventricular nucleus of the thalamus, hippocampus, supraoptic nucleus, suprachiasmatic nucleus, paraventricular nucleus of the hypothalamus, and the intermediolateral nucleus of and central autonomic area of the thoracic spinal cord. In contrast, in rats whose CFV was stimulated, these nuclei did not demonstrate changes in 2-DG uptake compared with control animals that received pressor doses of phenylephrine. These data have demonstrated some of the components of the neural circuitry likely involved in mediating the pressor responses to stimulation of the SFO and the corrective responses to activation of the SFO by disturbances to circulatory and fluid balance homeostasis.Key words: cardiovascular reflex pathways, drinking, median preoptic nucleus, osmoreceptors, paraventricular nucleus of the hypothalamus, supraoptic nucleus.

Hypothalamic projections of renal afferent nerves in the cat

1980 ◽  
Vol 58 (5) ◽  
pp. 574-576 ◽  
Author(s):  
J. Ciriello ◽  
F. R. Calaresu
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Paraventricular Nucleus ◽  
Fluid Balance ◽  
Lateral Hypothalamus ◽  
Discharge Rate ◽  
Renal Nerves ◽  
Preoptic Nucleus ◽  
Afferent Nerves ◽  
Stimulation Of

In 10 cats anaesthetized with chloralose the electrical activity of spontaneously active hypothalamic units was recorded for changes in discharge rate during electrical stimulation of renal afferent nerves. The discharge rate of 141 single units was altered by stimulation of either the ipsilateral or contralateral renal nerves. Most of the responsive units were located in the regions of lateral preoptic nucleus, lateral hypothalamus, and paraventricular nucleus. These results demonstrate that renal afferent nerves provide information to hypothalamic structures known to be involved in the regulation of arterial pressure and fluid balance.

Vasoconstrictor and vasodilator sites within anteroventral third ventricle region

1987 ◽  
Vol 253 (6) ◽  
pp. R827-R831 ◽  
Author(s):  
M. L. Mangiapane ◽  
M. J. Brody
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Third Ventricle ◽  
Renal Vascular Resistance ◽  
Preoptic Nucleus ◽  
Median Preoptic Nucleus ◽  
Tungsten Microelectrode ◽  
Renal Vascular ◽  
Stimulation Of

Previous studies have shown that electrical stimulation of the rat anteroventral third ventricle (AV3V) region produces a characteristic pattern of hemodynamic effects, i.e., renal and mesenteric vasoconstriction, and hindquarters vasodilation. In the present study, we localized the vasoconstrictor and vasodilator effects to specific subregions of the AV3V. In urethan-anesthetized rats prepared with arterial catheters and pulsed Doppler flow probes, we assessed the effects of electrical stimulation of four nuclei within AV3V on mean arterial pressure and renal, mesenteric, and hindquarters resistance. These nuclei were the organum vasculosum lamina terminalis (OVLT), ventral nucleus medianus (median preoptic nucleus), anterior (precommissural) nucleus medianus (median preoptic nucleus), and periventricular preoptic nuclei. Stimulation was carried out by use of a tungsten microelectrode. Stimulation of the OVLT consistently provoked stimulus-locked increases in arterial pressure coupled with increases in mesenteric and renal vascular resistance. Ganglionic blockade with chlorisondamine prevented these responses, demonstrating that they were mediated neurogenically. Stimulation of the three remaining nuclei produced decreases in arterial pressure, hindquarters vasodilation, and little change in mesenteric and renal vascular resistance. No changes in heart rate were observed with stimulation of any of the four nuclei. These results suggest that the vasoconstrictor and pressor functions of the AV3V region are localized in or near the OVLT region, whereas the remaining nuclei of the AV3V region mediate vasodilator and depressor responses.

Central noradrenergic activity in intact and sinoaortic denervated Dahl rats

1989 ◽  
Vol 67 (5) ◽  
pp. 450-455 ◽  
Author(s):  
K. P. Patel ◽  
J. D. Peuler ◽  
D. A. Morgan ◽  
B. J. Pardini ◽  
D. D. Lund ◽  
...  
Keyword(s):  
Paraventricular Nucleus ◽  
Genetic Predisposition ◽  
Supraoptic Nucleus ◽  
Locus Ceruleus ◽  
Preoptic Nucleus ◽  
Brain Areas ◽  
Brain Nuclei ◽  
Salt Diet ◽  
Median Preoptic Nucleus ◽  
Norepinephrine Turnover

Lesions in forebrain areas richly innervated by noradrenergic terminals and involved in cardiovascular function reduce or prevent hypertension in the Dahl salt-sensitive (S) rats fed a high (H) salt diet. This led us to examine two questions. (1) Is the noradrenergic activity altered in discrete forebrain and brainstem areas of SH rats? (2) Are these changes in noradrenergic activity eliminated by sinoaortic denervation (SAD)? Studies were done in 10-week-old female SH and Dahl salt-resistant (RH) rats. Half of the rats in each group had SAD surgery 1 week prior to study. An index of norepinephrine (NE) turnover was determined by measuring the decline in tissue NE concentration 8 h after administering α-methyl-p-tyrosine, a NE synthesis blocker, to animals from each of four groups: sham-RH, SAD-RH, sham-SH, and SAD-SH (n = 18–20 per group). Various discrete brain areas were obtained using the "punch technique." In SH rats the index of NE turnover was increased in the median preoptic nucleus and decreased in the paraventricular nucleus compared with RH rats regardless of SAD. In contrast, in SH rats the index of NE turnover was increased in the supraoptic nucleus and locus ceruleus compared with RH rats; however, SAD-RH had greater turnover of NE at these sites than SAD-SH. In summary, changes in noradrenergic activity in the median preoptic nucleus and the paraventricular nucleus may be related to genetic predisposition to hypertension in SH rats. In contrast, changes in the locus ceruleus and the supraoptic nucleus of SH rats may be related to impaired baroreflexes and thereby contribute to hypertension.Key words: hypertension, brain nuclei, norepinephrine, turnover.

Effect of paraventricular nucleus lesions on cardiovascular responses elicited by stimulation of the subfornical organ in the rat

1985 ◽  
Vol 63 (7) ◽  
pp. 816-824 ◽  
Author(s):  
Michael B. Gutman ◽  
John Ciriello ◽  
Gordon J. Mogenson
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Paraventricular Nucleus ◽  
Pressor Response ◽  
Cardiovascular Responses ◽  
Subfornical Organ ◽  
Short Latency ◽  
Peak Latency ◽  
Ganglionic Blockade ◽  
Stimulation Of

It has recently been reported that stimulation of the region of the subfornical organ (SFO) elicits an increase in arterial pressure. However, the mechanisms and forebrain neural circuitry that are involved in this cardiovascular response have not been elucidated. The present study was done in urethane-anaesthetized rats to determine whether selective activation of SFO neurons elicit cardiovascular responses and whether these responses were mediated by a pathway involving the paraventricular nucleus of the hypothalamus (PVH). Stimulation sites which required the lowest threshold current (30 μA) to elicit a pressor response and at which the largest rise in mean arterial pressure (MAP; 22 ± 2 mmHg) was elicited at a constant current intensity (150 μA) were histologically localized in the region of the SFO. Short (mean peak latency; 4 ± 2 s) and long (mean peak latency; 61 ± 8 s) latency increases in MAP were observed during and after electrical stimulation of the SFO, respectively. Cardiac slowing accompanied the short latency pressor response and cardioacceleration was observed in most (57%) of the cases to accompany the late pressor response. Microinjection of L-glutamate into the SFO consistently elicited cardiovascular responses qualitatively similar to those observed during electrical stimulation. Ganglionic blockade abolished the short latency increase in MAP and the accompanying bradycardia. However, the long latency pressor and cardioacceleratory responses were not altered by ganglionic blockade and adrenalectomy. Selective bilateral electrolytic or kainic acid lesions of the region of the PVH significantly attenuated the cardiovascular responses elicited by stimulation of the SFO. These data suggest that activation of neurons in the SFO elicit cardiovascular responses partially mediated by sympathetic outflow through a neural pathway involving the PVH.

Subfornical organ disconnection alters Fos expression in the lamina terminalis, supraoptic nucleus, and area postrema after intragastric hypertonic NaCl

2005 ◽  
Vol 288 (4) ◽  
pp. R947-R955 ◽  
Author(s):  
Julia A. Freece ◽  
Julie E. Van Bebber ◽  
Dannielle K. Zierath ◽  
Douglas A. Fitts
Keyword(s):  
Supraoptic Nucleus ◽  
Area Postrema ◽  
Anterior Commissure ◽  
Subfornical Organ ◽  
Main Body ◽  
Lamina Terminalis ◽  
Preoptic Nucleus ◽  
Median Preoptic Nucleus ◽  
Organum Vasculosum Laminae Terminalis ◽  
Initial Load

The lamina terminalis was severed by a horizontal knife cut through the anterior commissure to determine the effects of a disconnection of the subfornical organ (SFO) on drinking and Fos-like immunoreactivity (Fos-ir) in the rat brain in response to an intragastric load of hypertonic saline (5 ml/kg of 1.5 M NaCl by gavage). After an initial load, knife-cut rats drank significantly less water than sham-cut rats, thus confirming a role for the SFO in osmotic drinking. After a second load at least 1 wk later, the rats were not allowed to drink after the gavage and were perfused for analysis of Fos-ir at 90 min. Compared with sham-cut rats, the knife-cut rats displayed significantly elevated Fos-ir in the main body of the SFO, in the dorsal cap of the organum vasculosum laminae terminalis, and in the ventral median preoptic nucleus after the hypertonic load. The knife cut significantly decreased Fos-ir in the supraoptic nucleus. Fos-ir was expressed mainly in the midcoronal and caudal parts of the area postrema of sham-cut rats, and this expression was greatly reduced in knife-cut rats. These findings strengthen the case for the presence of independently functioning osmoreceptors within the SFO and suggest that the structures of the lamina terminalis provide mutual inhibition during hypernatremia. They also demonstrate that the Fos-ir in the area postrema after intragastric osmotic loading is heavily dependent on the intact connectivity of the SFO.

Vagal afferent inhibition of primate thoracic spinothalamic neurons

1983 ◽  
Vol 50 (4) ◽  
pp. 926-940 ◽  
Author(s):  
W. S. Ammons ◽  
R. W. Blair ◽  
R. D. Foreman
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Background Activity ◽  
Linear Regression Analysis ◽  
Cell Activity ◽  
High Threshold ◽  
Thoracic Spinal Cord ◽  
Afferent Fibers ◽  
Vagal Afferent ◽  
Stimulation Of

Spinothalamic (ST) neurons in the C8-T5 segments of the spinal cord were examined for responses to electrical stimulation of the left thoracic vagus nerve (LTV). Seventy-one ST neurons were studied in 39 anesthetized monkeys (Macaca fascicularis). Each neuron could be excited by manipulation of its somatic field and by electrical stimulation of cardiopulmonary sympathetic afferent fibers. LTV stimulation resulted in inhibition of the background activity of 43 (61%) ST neurons. Nine (13%) were excited, 3 (4%) were excited and then inhibited, while 16 (22%) did not respond. There was little difference among these groups in terms of the type of somatic or sympathetic afferent input although inhibited cells tended to be more prevalent in the more superficial laminae. The degree of inhibition resulting from LTV stimulation was related, in a linear fashion, to the magnitude of cell activity before stimulation. LTV inhibition of background activity was similar among wide dynamic range, high threshold, and high-threshold cells with inhibitory hair input. Any apparent differences in LTV inhibitory effects among these groups were accounted for by the differences in ongoing cell activity as predicted by linear regression analysis. LTV stimulation inhibited responses of 32 of 32 ST cells to somatic stimuli. In most cases the stimulus was a noxious pinch; however, LTV stimulation also inhibited responses to innocuous stimuli such as hair movement. Bilateral cervical vagotomy abolished the inhibitory effect of LTV stimulation on background activity (six cells) or responses to somatic stimuli (seven cells). Stimulation of the cardiac branch of the vagus inhibited activity of three cells to a similar degree as LTV stimulation, while stimulation of the vagus below the heart was ineffective in reducing activity of 10 cells. We conclude that LTV stimulation alters activity of ST neurons in the upper thoracic spinal cord. Vagal inhibition of ST cell activity was due to stimulation of cardiopulmonary vagal afferent fibers coursing to the brain stem, which appear to activate descending inhibitory spinal pathways. Vagal afferent activity may participate in processing of somatosensory information as well as information related to cardiac pain.

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