Cardiovascular regulation and expressions of NO synthase-tyrosine hydroxylase in nucleus tractus solitarius of ovine fetus

Ma, Sheng-Xing; Fang, Qun; Morgan, B. L.; Ross, Michael G.; Chao, Conrad R.

doi:10.1152/ajpheart.00718.2002

Cited by 10 publications

(5 citation statements)

References 29 publications

(71 reference statements)

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“…Chan et al (3) have reported pharmacologic data demonstrating roles for both iNOS and nNOS as modulators of neuronal mechanisms controlling cardiovascular function. Ma and colleagues (14) have presented data that suggest that reflex activity might be modulated by the synthesis and release of nitric oxide in the relevant brainstem nuclei. If so, developmental changes in the activity of the baroreflex might be partly explained by an ontogenetic change in the capacity for biosynthesis of nitric oxide in these brainstem nuclei.…”

Section: Discussionmentioning

confidence: 99%

“…nNOS expression in the medulla has been reported by numerous laboratories and is widely regarded as the major nitric oxide-producing enzyme in medullary neurons (14). As such, nNOS expression is well characterized in the nucleus tractus solitarius, as well as other medullary regions important for baroreceptor and chemoreceptor reflex function (20).…”

Section: Discussionmentioning

confidence: 99%

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Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem

Wood¹,

Chen²,

Keller‐Wood³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Wood, Charles E., Gin-Fu Chen, and Maureen Keller-Wood. Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem. Am J Physiol Regul Integr Comp Physiol 289: R613-R619, 2005; doi:10.1152/ajpregu.00722.2004.-Fetal baroreflex responsiveness increases in late gestation. An important modulator of baroreflex activity is the generation of nitric oxide in the brainstem nuclei that integrate afferent and efferent reflex activity. The present study was designed to test the hypothesis that nitric oxide synthase (NOS) isoforms are expressed in the fetal brainstem and that the expression of one or more of these enzymes is reduced in late gestation. Brainstem tissue was rapidly collected from fetal sheep of known gestational ages (80, 100, 120, 130, 145 days gestation and 1 day and 1 wk postnatal). Neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) mRNA was measured using real-time PCR methodology specific for ovine NOS isoforms. The three enzymes were measured at the protein level using Western blot methodology. In tissue prepared for histology separately, the cellular pattern of immunostaining was identified in medullae from late-gestation fetal sheep. Fetal brainstem contained mRNA and protein of all three NOS isoforms, with nNOS the most abundant, followed by iNOS and eNOS, respectively. nNOS and iNOS mRNA abundances were highest at 80 days' gestation, with statistically significant decreases in abundance in more mature fetuses and postnatal animals. nNOS and eNOS protein abundance also decreased as a function of developmental age. nNOS and eNOS were expressed in neurons, iNOS was expressed in glia, and eNOS was expressed in vascular endothelial cells. We conclude that all three isoforms of NOS are constitutively expressed within the fetal brainstem, and the expression of all three forms is reduced with advancing gestation. We speculate that the reduced expression of NOS in this brain region plays a role in the increased fetal baroreflex activity in late gestation. medulla; messenger ribonucleic acid; immunohistochemistry; realtime reverse transcriptase-polymerase chain reaction IN ADDITION TO ITS ROLE as an endothelial cell-derived vascular smooth muscle relaxant, the role of nitric oxide as a neurotransmitter is well established (11). In the medullary nuclei of the adult animal, nitric oxide is synthesized by neurons that express the neuronal form of nitric oxide synthase (nNOS or NOSIII) (3, 23). One of the physiological roles of nNOS in medullary neurons is the local generation of NO that, in turn, acts as an inhibitory neurotransmitter with regard to baroreflex responsiveness (13). Numerous studies in this laboratory have helped to establish the importance of baroreceptor and chemoreceptor reflexes in the minute-to-minute control of blood pressure and umbilical-placental blood flow in the fetus in utero (24,27). Various studies have demonstrated that the reflex mechanisms governing cardiovascular function in the fetus mature as a function of fetal gestational age (18,19...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem

Wood¹,

Chen²,

Keller‐Wood³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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“…However, the locations of TH-positive neurons is not restricted to known cell groupings. Immuno histochemical reactions for TH demonstrated monoaminergic neurons in the SolTN, where their numbers have been assessed by different authors as 12-18% [19,20]. We did not fi nd any convincing data demonstrating the presence and numbers of TH-positive neurons in other vasomotor nuclei with active roles in the mechanisms regulating the circulation.…”

Section: Discussionmentioning

confidence: 62%

“…This conclusion also has morphological grounds: in the SolTN, for example, along with TH-positive neurons, up to 14% of NADPH-d-positive neurons were seen, some of which (about 8%) were colocated with TH-immunopositive cells [10,19] although other data indicate that only 3% of TH-positive neurons in the rat brainstem are colocated with nNOS-containing cells [13]. Considering that the locations and quantitative distributions of NADPH-d and nNOS in nuclei have quite often failed to coincide in our previous studies [6,7], we used a more specifi c immunohistochemical reaction for nNOS to detect NO neurons.…”

Section: Discussionmentioning

confidence: 84%

Comparative Study of Catecholaminergic and Nitroxidergic Neurons in the Vasomotor Nuclei of the Caudal Part of the Brainstem in Rats

Черток

Kotsyuba

2015

Neurosci Behav Physi

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A leading role in the central regulation of the blood circulation is traditionally assigned to the monoaminergic mechanisms of the bulbar component of the cardiovascular center, whose activity is supported by small groups of noradrenergic neurons located between the nuclei of the caudal part of the brainstem [5,12,20,23]. Some reports indicate that nitric oxide (NO) has modulatory infl uences on the central vasomotor effects of the sympathetic nervous system: experimental treatments increasing or decreasing the concentration of this signal molecule inevitably lead to changes in the electrical activity of the sympathetic nerves and hemodynamic shifts [11,21]. The presence of numerous NOergic neurons in the vasomotor nuclei and transformations in these neurons during the development of arterial hypertension [2, 3] also provide evidence for the involvement of NO in the central mechanisms controlling hemodynamics. However, neither these nor other analogous studies contain any data on the quantitative distribution of catecholaminergic (CAergic) and NOergic neurons in nuclei known for their vasomotor functions; this was the motivation for the studies reported here. Materials and MethodsExperiments were performed in compliance with the "Regulations for Studies Using Experimental Animals" (USSR Ministry of Health Decree No. 755 of August 12, 1977) using 12 Wistar rats weighing 200-250 g and kept in laboratory animal house conditions on a standard diet. Animals were sacrifi ced by overdosage with 3% thiopental sodium solution, brains were extracted from the skull, and the medulla oblongata was detached and fi xed at 4°C for 4 h in 4% paraformaldehyde solution in 0.1 M sodium phosphate buffer pH 7.4 followed by washing in 0.1 M phosphate buffered saline for 24 h pH 7.4. Fixed material was washed with cold 30% sucrose solution in 0.1 M phosphate buffer and cryostat sections of thickness 30-40 μm were cut. Specimens were then processed for immunocytochemical detection of tyrosine hydroxylase (TH), an enzyme involved in catecholamine synthesis [21], and the Immunohistochemical studies in 12 Wistar rats detected tyrosine hydroxylase (TH) and the neuronal form of nitric oxide synthase (nNOS) to address the distribution of catecholaminergic and nitroxidergic neurons, respectively, in the vasomotor nuclei of the medulla oblongata and pons. The highest frequency of TH expression was seen in neurons located in these nuclei and some reticular nuclei (the gigantocellular, paragigantocellular, and caudal nuclei of the pons), though the proportions of immunoreactive neurons in these structures were no greater than 8-14%. In other nuclei (the reticular parvocellular and oral nucleus of the pons, the spinal nucleus of the trigeminal nerve), this proportion ranged from 1 to 3%. Neurons of this type were consistently not detected in a large group of nuclei with confi rmed vasomotor functions. Structures with many catecholaminergic neurons generally contained fewer nNOS-positive cells than nuclei with limited numbers of TH-positive neurons.

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“…Известно также, что в физиологических условиях NO облегчает процессы передачи сенсорной информации внутри ЯСТ, обеспечивая тем самым барорецепторное торможение СНС и стабильный уровень АД [8]. Микроинъекции в это ядро блокаторов синтеза NO, напротив, стимулируют увеличение электрической активности симпатических нервов и повышение АД [16,17].…”

Section: Discussionunclassified

Changes in spatial relationships between catecholamine- and nitroxidergic neurons in the nuclei of the caudal brain stem in the development of hypertension

Черток

Kotsyuba

Starceva

2018

Z. nevrol. psikhiatr. im. S.S. Korsakova

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The most early and severe changes in the intensity of reaction and amount of nNOS-positive neurons were noted in the solitary tract nucleus. Significant changes in the quantitative parameters of TH-positive neurons in RVH were identified only in the reticular giant cell nucleus but they appeared later and were less expressed compared to nNOS-positive cells. This resulted in the changes of spatial relationships between two types of neurons and remodeling of the bulbar region of the cardiovascular center.

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Cardiovascular regulation and expressions of NO synthase-tyrosine hydroxylase in nucleus tractus solitarius of ovine fetus

Cited by 10 publications

References 29 publications

Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem

Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem

Comparative Study of Catecholaminergic and Nitroxidergic Neurons in the Vasomotor Nuclei of the Caudal Part of the Brainstem in Rats

Changes in spatial relationships between catecholamine- and nitroxidergic neurons in the nuclei of the caudal brain stem in the development of hypertension

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