Activation within dorsal medullary nuclei following stimulation in the hypothalamic paraventricular nucleus in rats

Banks, D.; Harris, Mary

doi:10.1007/bf00581165

Cited by 21 publications

(18 citation statements)

References 33 publications

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“…A surprisingly high proportion of these retrogradely labeled mpPVN neurons (20 -25%) were also Fos-positive, regardless of whether the tracer deposit had been placed in the VLM or NTS. This finding, in combination with past reports that PVN stimulation activates VLM and NTS neurons (Krukoff et al, 1994;Banks and Harris, 1987), leads us to suggest that the reduction in psychological stress-induced CA cell activation caused by PVN lesions was probably due to interruption of direct, excitatory mpPVN projections to the VLM and NTS. The current study provides no information as to the neurochemical phenotype of these medulla-projecting mpPVN neurons, but previous studies have provided evidence consistent with a role for oxytocinergic neurons (Buijs et al, 1990;Petrov et al, 1995).…”

Section: Restraint-induced Fos Expression In Pvn Neurons That Projectmentioning

confidence: 51%

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Hypothalamic paraventricular nucleus neurons regulate medullary catecholamine cell responses to restraint stress

Dayas

Buller

Day

2004

J of Comparative Neurology

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Both physical and psychological stressors recruit catecholamine cells (CA) located in the ventrolateral medulla (VLM) and the nucleus of the solitary tract (NTS). In the case of physical stressors, this effect is initiated by signals that first access the central nervous system at or below the level of the medulla. For psychological stressors, however, CA cell recruitment depends on higher structures within the neuraxis. Indeed, we have recently provided evidence of a pivotal role for the medial amygdala (MeA) in this regard, although such a role must involve a relay, as MeA neurons do not project directly to the medulla. However, some of the MeA neurons that respond to psychological stress have been found to project to the hypothalamic paraventricular nucleus (PVN), a structure that provides significant input to the medulla. To determine whether the PVN might regulate medullary CA cell responses to psychological stress, animals were prepared with unilateral injections of the neurotoxin ibotenic acid into the PVN (Experiment 1), or with unilateral injections of the retrograde tracer wheat germ agglutinin-gold (WGA-Au) into the CA cell columns of the VLM or NTS (Experiment 2). Seven days later, animals were subjected to a psychological stressor (restraint; 15 minutes), and their brains were subsequently processed for Fos plus appropriate cytoplasmic markers (Experiment 1), or Fos plus WGA-Au (Experiment 2). PVN lesions significantly suppressed the stress-related induction of Fos in both VLM and NTS CA cells, whereas tracer deposits in the VLM or NTS retrogradely labeled substantial numbers of PVN cells that were also Fos-positive after stress. Considered in concert with previous results, these data suggest that the activation of medullary CA cells in response to psychological stress may involve a critical input from the PVN.

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Section: Restraint-induced Fos Expression In Pvn Neurons That Projectmentioning

confidence: 51%

“…Moreover, several studies have provided evidence that these projections can influence medullary CA cell activity (Banks and Harris, 1987;Krukoff et al, 1994). However, to the best of our knowledge, there have been no previous attempts to determine whether the PVN might feature in the initiation of medullary CA cell responses to psychological stress.…”

mentioning

confidence: 98%

Hypothalamic paraventricular nucleus neurons regulate medullary catecholamine cell responses to restraint stress

Dayas

Buller

Day

2004

J of Comparative Neurology

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“…B: calculated gain vs. MAP using same symbols as above. modulate the integration of baroreceptor afferent inputs within the medulla (1,10,26). Absolute level of RSNA.…”

Section: Discussionmentioning

confidence: 99%

“…Baroreflex resetting likely reflects some mixture of receptor resetting (25,29,40), and alterations in the central nervous system (CNS; 11,19,30,31,33,42), including descending modulation of medullary neurons integrating baroreceptor afferent inputs (1,10,26). A lack of resetting of the MAP-RSNA relationship has been reported in ANG II-infused HT rabbits (2), so that at resting levels of MAP, further inhibition of RSNA is not possible.…”

Section: Oe Oementioning

confidence: 99%

Baroreflex regulation of renal sympathetic nerve activity and heart rate in renal wrap hypertensive rats

Vitela¹,

Herrera-Rosales²,

Haywood³

et al. 2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Despite its usefulness as a nongenetic model of hypertension, little information is available regarding baroreflex function in the Grollman, renal wrap model of hypertension in the rat. Baroreflex regulation of renal sympathetic nerve activity (RSNA) and heart rate (HR) were studied in male, Sprague-Dawley rats hypertensive (HT) for 1 or 4-6 wk after unilateral nephrectomy and figure-8 ligature around the remaining kidney or normotensive (NT) after sham surgery. Rats were anesthetized with Inactin and RSNA, and HR was recorded during intravenous infusions of sodium nitroprusside or phenylephrine to lower or raise mean arterial pressure (MAP). Response curves were analyzed using a logistic sigmoid function. In 1- and 4-wk HT rats the midpoints of RSNA and HR reflex curves were shifted to the right (P < 0.05). Comparing NT to 1- or 4-wk HT rats, the gain of RSNA-MAP curves was no different; however, gain was reduced in the HR-MAP curves at both 1 and 4 wk in HT rats (P < 0.05). In anesthetized rats the HR range was small; therefore, MAP and HR were measured in conscious rats during intravenous injections of three doses of phenylephrine and three doses of sodium nitroprusside. Linear regressions revealed a reduced slope in both 1- and 4-wk HT rats compared with NT rats (P < 0.05). The results indicate that baroreflex curves are shifted to the right, to higher pressures, in hypertension. After 1-4 wk of hypertension the gain of baroreflex regulation of RSNA is not altered; however, the gain of HR regulation is reduced.

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“…The peptidergic projections from the PVN to the NTS may also mediate functions other than cardiovascular regulation. Indeed, it has been reported that the peptidergic projections from the PVN to the NTS may be involved in facilitating the effects of visceral afferent input from the abdominal vagus to the NTS (Banks and Harris, 1987;Kannan and Yamashita, 1985;Rogers and Hermann, 1985).…”

Section: Introductionmentioning

confidence: 99%

Cardiovascular function of a glutamatergic projection from the hypothalamic paraventricular nucleus to the nucleus tractus solitarius in the rat

et al. 2008

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Experiments were done in urethane-anesthetized, barodenervated, male Wistar rats. Chemical stimulation of the hypothalamic paraventricular nucleus (PVN) by unilateral microinjections of Nmethyl-D-aspartic acid (NMDA) elicited increases in mean arterial pressure (MAP) and greater splanchnic nerve activity (GSNA). The increases in the MAP and GSNA induced by chemical stimulation of the PVN were significantly exaggerated by bilateral microinjections of D-AP7 and NBQX (ionotropic glutamate receptor antagonists) into the medial subnucleus of the nucleus tractus solitarius (mNTS). These results were confirmed by single unit recordings; i.e., excitation of mNTS barosensitive neurons caused by chemical stimulation of the ipsilateral PVN was blocked by application of D-AP7 and NBQX to these neurons. Bilateral microinjections of D-AP7 and NBQX into the mNTS elicited pressor responses which were significantly attenuated by inhibition of PVN neurons by bilateral microinjections of muscimol. Unilateral microinjections of fluorogold into the mNTS resulted in bilateral retrograde labeling of the PVN neurons. Unilateral microinjections of biotinylated dextran amine into the PVN resulted in anterograde labeling of axons and terminals in the mNTS bilaterally and the labeled terminals exhibited vesicular glutamate transporter-2 immunoreactivity. These results indicated that; 1) a tonically active glutamatergic bilateral projection from the PVN to the mNTS exists, 2) bilateral blockade of ionotropic glutamate receptors in the mNTS exaggerates the increases in MAP and GSNA to the chemical stimulation of the PVN, and 3) this projection may serve as a restraint mechanism for excitatory cardiovascular effects of PVN stimulation.

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Activation within dorsal medullary nuclei following stimulation in the hypothalamic paraventricular nucleus in rats

Cited by 21 publications

References 33 publications

Hypothalamic paraventricular nucleus neurons regulate medullary catecholamine cell responses to restraint stress

Hypothalamic paraventricular nucleus neurons regulate medullary catecholamine cell responses to restraint stress

Baroreflex regulation of renal sympathetic nerve activity and heart rate in renal wrap hypertensive rats

Cardiovascular function of a glutamatergic projection from the hypothalamic paraventricular nucleus to the nucleus tractus solitarius in the rat

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