Solitary nucleus excitation of supraoptic vasopressin cells via adrenergic afferents

1988 ◽  
Vol 254 (4) ◽  
pp. R711-R716 ◽  
Author(s):  
T. A. Day ◽  
J. R. Sibbald
Keyword(s):  
Area Postrema ◽  
Activity Patterns ◽  
Neurosecretory Cells ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Direct Projection ◽  
Long Latency ◽  
6 Hydroxydopamine ◽  
Baroreceptor Activation ◽  
Arterial Baroreceptor

Recent studies confirm that the supraoptic nucleus (SON) receives a direct projection from the nucleus of the solitary tract (NTS). We have examined the effect of NTS stimulation on antidromically identified SON neurosecretory cells that were classified as arginine vasopressin (AVP) or oxytocin (OXY) secreting in accord with basal activity patterns and responsiveness to arterial baroreceptor activation. Medial NTS stimulation at the level of the obex or area postrema excited 78% (59 of 76) of putative AVP cells (onset latency 52 +/- 1 ms) but only 20% (3 of 15) of putative OXY cells. Commissural NTS stimulation did not excite AVP cells (n = 13). After complete SON catecholamine afferent disruption, achieved by local injection of 6-hydroxydopamine, AVP cells tested were unresponsive to medial NTS stimulation (12 of 13), although arterial baroreceptor activation inhibited four of four cells. These data indicate that medial NTS stimulation preferentially excites SON AVP cells and that this effect involves an adrenergic input to SON. A direct projection from the A2 catecholamine cell group of the NTS may be involved, although the long latency to excitation and the poor correspondence between effective NTS stimulation sites and the location of the A2 group within NTS raise the possibility that a relay projection, possibly through the A1 catecholamine cell group of the ventrolateral medulla, may be involved.

Medullary pathways mediating depressor responses from Na(+)-sensitive sites in nucleus of the solitary tract

1997 ◽  
Vol 272 (1) ◽  
pp. R126-R133 ◽  
Author(s):  
S. L. Hochstenbach ◽  
J. Ciriello
Keyword(s):  
Area Postrema ◽  
Cardiovascular Response ◽  
Nucleus Ambiguus ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Motor Nucleus ◽  
Solitary Tract ◽  
Male Wistar Rats ◽  
Efferent Projections ◽  
Series Of Experiments

Two series of experiments were done in male Wistar rats to investigate the medullary pathways that mediate the depressor responses from sodium-sensitive sites in the nucleus of the solitary tract (NTS). In the first series, the anterograde tract tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was iontophoresed unilaterally at sites in the NTS at which microinjections (20 nl) of a 154-175 mM NaCl solution elicited depressor responses. PHA-L injection sites were found to be localized within the medial subnucleus of the NTS (Sm). In the medulla, PHA-L-labeled fibers and presumptive terminal boutons were observed bilaterally, but with an ipsilateral predominance, throughout the rostrocaudal extent of the NTS the dorsal motor nucleus of the vagus, area postrema, the ventrolateral medulla (VLM), and nucleus ambiguus. The pontine region, containing the A5 catecholaminergic cell group and the parabrachial nucleus, also received projections from Sm. In the second series of experiments, the effect of blocking synaptic transmission in VLM with cobalt chloride (CoCl2; 5 mM, 100 nl) on the cardiovascular response elicited by microinjection (20 nl) of hypertonic saline (154-175 mM) into the ipsilateral Sm was investigated in the alpha-chloralose-anesthetized, paralyzed, and artificially ventilated rat. Microinjection of CoCl2 into VLM, at sites shown in the previous study to receive efferent projections from Sm, significantly attenuated the depressor (60%) and bradycardic (80%) responses to stimulation of Sm. These data indicate that the sodium-sensitive region of the caudal Sm innervates VLM neurons and suggest that these VLM neurons are involved in mediating the depressor and bradycardic responses elicited by changes in the extracellular concentration of sodium.

A1 cell group mediates solitary nucleus excitation of supraoptic vasopressin cells

1989 ◽  
Vol 257 (5) ◽  
pp. R1020-R1026 ◽  
Author(s):  
T. A. Day ◽  
J. R. Sibbald
Keyword(s):  
Nucleus Tractus Solitarius ◽  
Single Pulse ◽  
Neurosecretory Cells ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Onset Latency ◽  
Unit Recording ◽  
Inhibitory Neurotransmitter ◽  
Caudal Ventrolateral Medulla ◽  
Electrolytic Lesions

Stimulation of the nucleus tractus solitarius (NTS) excites putative vasopressin-secreting cells of the supraoptic nucleus (SON) via a catecholaminergic projection to hypothalamus. Despite recent evidence of a direct catecholaminergic projection from NTS to SON, we have performed single-unit recording experiments in pentobarbital sodium-anesthetized rats to investigate the possibility that NTS stimulation effects on SON vasopressin cells are indirect, being relayed via the A1 noradrenergic cell group of the caudal ventrolateral medulla. The effects of single-pulse NTS and A1 region stimulation on the activity of antidromically identified SON neurosecretory cells that had been functionally characterized as vasopressin secreting were compared. NTS stimulation excited 81% of all putative vasopressin-secreting cells tested (n = 83), with a mean onset latency of 51 +/- 1 ms. A1 region stimulation excited 76% of all cells tested and 90% of units responsive to NTS stimulation, with a mean latency of 39 +/- 1 ms. Consistent with previous work NTS stimulation excited only a minority of oxytocin cells tested (3/13), and of these two-thirds also responded to A1 stimulation. Bilateral electrolytic lesions of the A1 region abolished the effects of NTS stimulation on putative vasopressin cells. Ipsilateral A1 region injections of the inhibitory neurotransmitter gamma-amino-butyric acid reversibly blocked NTS stimulation effects on putative vasopressin cells in animals where the contralateral A1 region had already been lesioned. These results support the proposal that excitation of SON vasopressin-secreting cells after NTS stimulation is due to activation of a relay projection through the A1 noradrenergic cell group of the caudal ventrolateral medulla.

Noxious somatic stimuli excite neurosecretory vasopressin cells via A1 cell group

1990 ◽  
Vol 258 (6) ◽  
pp. R1516-R1520 ◽  
Author(s):  
T. A. Day ◽  
J. R. Sibbald
Keyword(s):  
Nerve Stimulation ◽  
Neurosecretory Cells ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Gamma Aminobutyric Acid ◽  
Unit Recording ◽  
Inhibitory Neurotransmitter ◽  
Caudal Ventrolateral Medulla ◽  
Somatic Nerve ◽  
Sciatic Nerve Stimulation

Activation of nociceptive somatic afferents excites hypothalamic neurosecretory cells and stimulates the release of vasopressin. To investigate the possibility that relevant afferent information is relayed through the A1 norepinephrine cell group of the caudal ventrolateral medulla, single-unit recording experiments were performed in pentobarbital sodium-anesthetized rats. The effects of somatic nerve stimulation, application of noxious somatic stimuli, and A1 region stimulation on the activity of putative vasopressin-secreting neurosecretory cells of the supraoptic nucleus were compared. The predominant effect of femoral and sciatic nerve stimulation on these cells was excitation, 54% (n tested = 113) displaying a marked increase in discharge probability, which had a mean onset latency of 72 +/- 3 ms and a mean duration of 114 +/- 9 ms. Almost all cells (96%) responding to somatic nerve stimulation were also excited by pinching of the ipsilateral or contralateral hindlimb paw, and the majority (84%) displayed a matching but shorter latency response to A1 region stimulation (mean onset 35 +/- 4 ms, duration 55 +/- 9 ms). A1 region injections of the inhibitory neurotransmitter gamma-aminobutyric acid reversibly blocked the effects of both somatic nerve stimulation (n = 14) and paw pinch (n = 9) on putative vasopressin cells. These results indicate that excitation of vasopressinergic neurosecretory cells by noxious somatic stimuli requires activation of neurons of the caudal ventrolateral medulla and hence are consistent with the proposal of a role for the A1 norepinephrine cell group.

Cardiovascular regulation after destruction of the C1 cell group of the rostral ventrolateral medulla in rats

2003 ◽  
Vol 285 (6) ◽  
pp. H2734-H2748 ◽  
Author(s):  
Christopher J. Madden ◽  
Alan F. Sved
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Cell Population ◽  
Cardiovascular Regulation ◽  
Neuronal Population ◽  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Integral Role ◽  
6 Hydroxydopamine

To evaluate the role of C1 neurons in the rostral ventrolateral medulla (RVLM) in cardiovascular regulation, we studied rats in which this cell group was destroyed by the injection of anti-dopamine-β-hydroxylase-saporin into the RVLM. These immunotoxin injections resulted in 32–99% depletion of the RVLM-C1 neurons and ∼50% depletion of the A5 cell population. In conscious rats with large (>80%) depletion of the RVLM-C1 cell population, resting arterial pressure was ∼10 mmHg lower than in control injected rats, although heart rate was not significantly different. Similar results were observed when arterial pressure was recorded in urethan-anesthetized rats, although under anesthesia, heart rate was also reduced in rats with large (>80%) depletion of the RVLM-C1 neuronal population. Sympathoexcitatory responses to baroreceptor unloading, chemoreceptor activation, and electrical stimulation of sciatic nerve afferent fibers were attenuated in rats with >80% depletion of the RVLM-C1 cell population. These effects of RVLM-C1 plus A5 cell populations were not mimicked by either smaller lesions of the RVLM-C1 population or by selective destruction of the A5 cell population with 6-hydroxydopamine. Sympathoinhibitory responses such as decreases in arterial pressure and heart rate evoked by injection of GABA into the RVLM or by intravenous phenylbiguanide administration were not altered by RVLM-C1 plus A5 cell depletion. These data suggest that RVLM-C1 cells contribute to the maintenance of baseline arterial pressure and play an integral role in sympathoexcitatory responses.

Fos expression in brain stem nuclei of pregnant rats after hydralazine-induced hypotension

1999 ◽  
Vol 277 (2) ◽  
pp. R532-R540 ◽  
Author(s):  
Kathleen S. Curtis ◽  
J. Thomas Cunningham ◽  
Cheryl M. Heesch
Keyword(s):  
Area Postrema ◽  
Virgin Female ◽  
Female Rats ◽  
Ventrolateral Medulla ◽  
Pregnant Rats ◽  
Induced Hypotension ◽  
Central Response ◽  
Vehicle Treatment ◽  
Fos Expression ◽  
The Brain

Fos and dopamine β-hydroxylase immunoreactivity were evaluated in the brain stems of 21-day pregnant and virgin female rats injected with either hydralazine (HDZ; 10 mg/kg iv) or vehicle. HDZ produced significant hypotension in both groups, although baseline blood pressure was lower in pregnant rats (96 ± 2.5 mmHg) than in virgin female rats (121 ± 2.8 mmHg). There were no differences in Fos immunoreactivity in the brain stems of pregnant and virgin female rats after vehicle treatment. HDZ-induced hypotension significantly increased Fos expression in both groups; however, the magnitude of the increases differed in the caudal ventrolateral medulla (CVL), the area postrema (AP), and the rostral ventrolateral medulla (RVL). Fos expression after HDZ in pregnant rats was augmented in noncatecholaminergic neurons of the CVL but was attenuated in the AP and in noncatecholaminergic neurons in the RVL. These results are consistent with differences in the sympathetic response to hypotension between pregnant and virgin female rats and indicate that the central response to hypotension may be different in pregnant rats.

scholarly journals Vasopressin in the area postrema modulates arterial baroreceptor reflex in rats

2000 ◽  
Vol 82 ◽  
pp. 77
Author(s):  
Hideto Ariumi ◽  
Koichiro Saito ◽  
Ryo Saito ◽  
Kenji Honda ◽  
Yukio Takano ◽  
...  
Keyword(s):  
Area Postrema ◽  
Baroreceptor Reflex ◽  
Arterial Baroreceptor Reflex ◽  
Arterial Baroreceptor

Cell types and response timings in the medial interlaminar nucleus and C-layers of the cat lateral geniculate nucleus

1999 ◽  
Vol 16 (3) ◽  
pp. 513-525 ◽  
Author(s):  
ALLEN L. HUMPHREY ◽  
ADITYA MURTHY
Keyword(s):  
Cell Types ◽  
Direction Selectivity ◽  
Extrastriate Cortex ◽  
Cell Group ◽  
Absolute Phase ◽  
Long Latency ◽  
Lagged Cells ◽  
Discharge Patterns ◽  
Response Timing ◽  
X Cells

Previous evidence concerning the physiological cell classes in the medial interlaminar nucleus (MIN) has been conflicting. We reexamined the MIN using standard functional tests to distinguish X-, Y- and W-cells. Discharge patterns to flashing spots also were used to identify some cells as lagged or nonlagged, as previously done for the geniculate A-layers. Also, each cell's response timing (latency and absolute phase) was measured from discharges to a spot undergoing sinusoidal luminance modulation. Of 71 MIN cells, 48% were Y, 27% were W, 8% were X, and 17% were unclassifiable. Lagged and nonlagged discharge profiles were observed in each cell group, with 28% of all cells being lagged. Lagged cells displayed a response suppression and long latency to discharge following spot onset, and a slow decay in firing at spot offset that was often preceded by a transient discharge. These profiles were indistinguishable from those of lagged cells in the A-layers. MIN cells also were heterogeneous in response timing, displaying a range of latency and absolute phase values similar to that in the A-layers. We extended these analyses to 27 cells in the geniculate C-layers. In layer C, 35% of cells were Y, 10% were X, 25% were W, and 30% were unclassifiable. About 11% had lagged profiles, and were X-cells or unclassifiable cells. Layers C1 and C2 contained only W-cells and no lagged profiles. The range of timings in the C-layers was somewhat narrower than in the MIN. Overall, these results show that the MIN contains a greater variety of functional cell classes than heretofore appreciated. Further, it appears that mechanisms which create different timing delays in the A-layers also exist in the MIN and layer C. These timings may contribute to direction selectivity in extrastriate cortex.

Raphe pallidus excites a unique class of sympathetic preganglionic neurons

1993 ◽  
Vol 265 (1) ◽  
pp. R82-R89 ◽  
Author(s):  
S. F. Morrison
Keyword(s):  
Splanchnic Nerve ◽  
Short Latency ◽  
Ventrolateral Medulla ◽  
Conduction Time ◽  
Antidromic Activation ◽  
Sympathetic Preganglionic Neurons ◽  
Preganglionic Neurons ◽  
Long Latency ◽  
Excitatory Responses ◽  
Raphe Pallidus

The responses of splanchnic sympathetic preganglionic neurons (SPNs) to stimulation in raphe pallidus and in rostral ventrolateral medulla (RVLM) were compared to determine the basis for the excitatory responses evoked in the whole splanchnic preganglionic nerve bundle. Most (88%) of the SPNs with a short-latency (32 ms) excitatory response to RVLM stimulation were unaffected by raphe pallidus stimulation, although 12% were excited at a long latency (123 ms). Each of the SPNs with long-latency (114 ms) excitatory responses to RVLM stimulation was also excited by raphe pallidus stimulation at latencies (106 ms) that were 7 ms (P < 0.01) shorter than those evoked from the RVLM. Antidromic activation of raphe pallidus neurons from both the T8 intermediolateral nucleus (98 ms) and from the RVLM (18 ms) indicated that their spinally projecting axons emit collaterals (mean conduction time: 12 ms) into the ventrolateral medulla. In conclusion, the short-latency (70 ms) splanchnic nerve excitation evoked by RVLM stimulation is mediated primarily by SPNs that do not respond to raphe pallidus stimulation. Similarly, the long-latency (162 ms) splanchnic excitation evoked from the raphe pallidus is mediated primarily by SPNs that do not respond to the rapidly conducting sympathoexcitatory pathway from the RVLM. The long-latency (169 ms), RVLM stimulus-evoked excitation of the splanchnic nerve may arise from action potentials conducted on the axonal branches of raphe spinal neurons.

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