Autonomic processing of the cardiovascular reflexes in the nucleus tractus solitarii

Machado, Benedito H.; Mauad, Helder; Chianca, D.A.; Haibara, Andréa Siqueira; Colombari, Eduardo

doi:10.1590/s0100-879x1997000400015

Cited by 66 publications

(57 citation statements)

References 47 publications

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“…The lateral parabrachial subnuclei respond to painful stimuli (Lanteri-Minet et al, 1994;Bester et al, 2000), and the strong projection from this area to the VLPO may play a role in the alterations of sleep induced by pain. The VLPO receives inputs from the infralimbic cortex and nucleus of the solitary tract, areas implicated in the regulation of cardiovascular, respiratory, and other autonomic functions (Cechetto and Saper, 1987;Machado et al, 1997). Hence, changes in autonomic function could influence sleep via these pathways.…”

Section: Functional Implicationsmentioning

confidence: 99%

Afferents to the Ventrolateral Preoptic Nucleus

et al. 2002

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Sleep is influenced by diverse factors such as circadian time, affective states, ambient temperature, pain, etc., but pathways mediating these influences are unknown. To identify pathways that may influence sleep, we examined afferents to the ventrolateral preoptic nucleus (VLPO), an area critically implicated in promoting sleep. Injections of the retrograde tracer cholera toxin B subunit (CTB) into the VLPO produced modest numbers of CTB-labeled monoaminergic neurons in the tuberomammillary nucleus, raphe nuclei, and ventrolateral medulla, as well as a few neurons in the locus coeruleus. Immunohistochemistry for monoaminergic markers showed dense innervation of the VLPO by histaminergic, noradrenergic, and serotonergic fibers. Along with previous findings, these results suggest that the VLPO and monoaminergic nuclei may be reciprocally connected. Retrograde and anterograde tracing showed moderate or heavy inputs to the VLPO from hypothalamic regions including the median preoptic nucleus, lateral hypothalamic area, and dorsomedial hypothalamic nucleus (DMH), autonomic regions including the infralimbic cortex and parabrachial nucleus, and limbic regions including the lateral septal nucleus and ventral subiculum. Light to moderate inputs arose from orexin and melanin concentrating hormone neurons, but cholinergic or dopaminergic inputs were extremely sparse. Suprachiasmatic nucleus (SCN) projections to the VLPO were sparse, but the heavy input to the VLPO from the DMH, which receives direct and indirect SCN inputs, could provide an alternate pathway regulating the circadian timing of sleep. These robust pathways suggest candidate mechanisms by which sleep may be influenced by brain systems regulating arousal, autonomic, limbic, and circadian functions.

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Section: Functional Implicationsmentioning

confidence: 99%

Afferents to the Ventrolateral Preoptic Nucleus

et al. 2002

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“…An organism copes with blood fluctuations by intrinsic, neural and humoral regulatory mechanisms (1). Of particular interest to the present research, neural regulatory mechanisms, more specifically baroreceptor feedback control, are characterized by their prompt effect (1) on a beat-to-beat time scale (2).…”

Section: Introductionmentioning

confidence: 99%

Baroreflex function in conscious rats submitted to iron overload

Cardoso

Pedrosa

Silva

et al. 2005

Braz J Med Biol Res

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Our hypothesis is that iron accumulated in tissue, rather than in serum, may compromise cardiovascular control. Male Fischer 344 rats weighing 180 to 220 g were divided into 2 groups. In the serum iron overload group (SIO, N = 12), 20 mg elemental iron was injected ip daily for 7 days. In the tissue iron overload group (TIO, N = 19), a smaller amount of elemental iron was injected (10 mg, daily) for 5 days followed by a resting period of 7 days. Reflex heart rate responses were elicited by iv injections of either phenylephrine (0.5 to 5.0 µg/kg) or sodium nitroprusside (1.0 to 10.0 µg/kg). Baroreflex curves were determined and fitted to sigmoidal equations and the baroreflex gain coefficient was evaluated. To evaluate the role of other than a direct effect of iron on tissue, acute treatment with the iron chelator deferoxamine (20 mg/kg, iv) was performed on the TIO group and the baroreflex was reevaluated. At the end of the experiments, evaluation of iron levels in serum confirmed a pronounced overload for the SIO group (30-fold), in contrast to the TIO group (2-fold). Tissue levels of iron, however, were higher in the TIO group. The SIO protocol did not produce significant alterations in the baroreflex curve response, while the TIO protocol produced a nearly 2-fold increase in baroreflex gain (-4.34 ± 0.74 and -7.93 ± 1.08 bpm/mmHg, respectively). The TIO protocol animals treated with deferoxamine returned to sham levels of baroreflex gain (-3.7 ± 0.3 sham vs -3.6 ± 0.2 bpm/mmHg) 30 min after the injection. Our results indicate an effect of tissue iron overload on the enhancement of baroreflex sensitivity.

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“…Studies from our laboratory have evaluated the autonomic processing of the cardiovascular reflexes in the nucleus tractus solitarii (NTS), with particular emphasis on the role of excitatory amino acid (EAA) receptors (1)(2)(3)(4)(5)(6). Several studies have indicated a major role for L-glutamate and the different subtypes of EAA receptors in this neurotransmission (7)(8)(9)(10).…”

Section: Introductionmentioning

confidence: 99%

Blockade of NK-1 receptors in the lateral commissural nucleus tractus solitarii of awake rats had no effect on the cardiovascular responses to chemoreflex activation

Zhang

Bonagamba

Machado

2000

Braz J Med Biol Res

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The neurotransmission of the chemoreflex in the nucleus tractus solitarii (NTS), particularly of the sympatho-excitatory component, is not completely understood. There is evidence that substance P may play a role in the neurotransmission of the chemoreflex in the NTS. Microinjection of substance P (50 pmol/50 nl, N = 12, and 5 nmol/50 nl, N = 8) into the commissural NTS of unanesthetized rats produced a significant increase in mean arterial pressure (101 ± 1 vs 108 ± 2 and 107 ± 3 vs 115 ± 4 mmHg, respectively) and no significant changes in heart rate (328 ± 11 vs 347 ± 15 and 332 ± 7 vs 349 ± 13 bpm, respectively) 2 min after microinjection. Previous treatment with WIN, an NK-1 receptor antagonist (2.5 nmol/50 nl), microinjected into the NTS of a specific group of rats, blocked the pressor (11 ± 5 vs 1 ± 2 mmHg) and tachycardic (31 ± 6 vs 4 ± 3 bpm) responses to substance P (50 pmol/50 nl, N = 5) observed 10 min after microinjection. Bilateral microinjection of WIN into the lateral commissural NTS (N = 8) had no significant effect on the pressor (50 ± 4 vs 42 ± 6 mmHg) or bradycardic (-230 ± 16 vs -220 ± 36 bpm) responses to chemoreflex activation with potassium cyanide (iv). These data indicate that the activation of NK-1 receptors by substance P in the NTS produces an increase in baseline mean arterial pressure and heart rate. However, the data obtained with WIN suggest that substance P and NK-1 receptors do not play a major role in the neurotransmission of the chemoreflex in the lateral commissural NTS.

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Autonomic processing of the cardiovascular reflexes in the nucleus tractus solitarii

Cited by 66 publications

References 47 publications

Afferents to the Ventrolateral Preoptic Nucleus

Afferents to the Ventrolateral Preoptic Nucleus

Baroreflex function in conscious rats submitted to iron overload

Blockade of NK-1 receptors in the lateral commissural nucleus tractus solitarii of awake rats had no effect on the cardiovascular responses to chemoreflex activation

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