Suitability of urethane anesthesia for physiopharmacological investigations. Part 3: Other systems and conclusions

Maggi, Carlo Alberto; Meli, Alberto

doi:10.1007/bf01946692

Cited by 128 publications

(56 citation statements)

References 61 publications

(2 reference statements)

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“…Our choice of urethane as the anesthetic for these stud ies was based on the demonstration that sympathetic and parasympathetic reflexes are maintained during anesthe sia [27,28]. The present results confirm those from our earlier studies [7,10] that urethane anesthesia is associat ed with expression of FLI neurons of areas such as the NTS, VLM, PBN and VMH.…”

Section: Controlssupporting

confidence: 82%

Expression of c-fos Protein in Rat Brain Elicited by Electrical and Chemical Stimulation of the Hypothalamic Paraventricular Nucleus

Krukoff¹,

Harris²,

Linetsky³

et al. 1994

Neuroendocrinology

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The functional connectivity of the paraventricular nucleus of the hypothalamus (PVN) was studied by assessing the expression of the immediate early gene, c-fos, after unilateral stimulation of this structure in urethane-anesthetized rats. Electrical stimulation for 1 h (10 s on, 10 s off; 15-40 µA at 20 Hz) was accompanied by increases in mean arterial pressure (13-29 mm Hg). In these animals, ipsilateral increases in numbers of neurons with Fos-like immunoreactivity (FLI) were immunohistochemically demonstrated in the insular cortex, lateral septum, medial amygdala, hypothalamus, lateral division of the parabrachial nucleus (PBN) of the pons and the nucleus of the tractus solitarius (NTS) and ventrolateral medulla (VLM). Numbers of cells with FLI were quantitated in five areas known for their roles in autonomic function: arcuate nucleus, ventromedial hypothalamus, lateral PBN, NTS (at three levels) and VLM (caudal and rostral). In each case, stimulation of the PVN led to significant differences in number of neurons with FLI on the side ipsilateral to the stimulation compared to the contralateral side. To eliminate effects associated with stimulation of fibers of passage in the vicinity of the PVN, the results after electrical stimulation were compared to those obtained in animals in which the PVN was chemically stimulated unilaterally with the excitatory amino acid L-glutamate (5 one-minute infusions of 50 nl, 0.5 M glutamate over 1 h). Mean arterial pressure was increased after each injection (7–13 mm Hg), and significant differences in numbers of neurons with FLI between sides were maintained in all five areas except the NTS caudal to, and at, the level of the area postrema. An increase in neurons with FLI in the piriform cortex of all animals including controls may be due to injury-induced activation of target neurons from the PVN. These data illustrate that electrical and chemical stimulation of the PVN leads to simultaneous activation of neurons in many targets. All of the target areas studied receive direct projections from the PVN, although multisynaptic projections may also contribute to activation of target neurons.

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Section: Controlssupporting

confidence: 82%

Expression of c-fos Protein in Rat Brain Elicited by Electrical and Chemical Stimulation of the Hypothalamic Paraventricular Nucleus

Krukoff¹,

Harris²,

Linetsky³

et al. 1994

Neuroendocrinology

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“…This is important to consider given the actions of the renin-angiotensin system in mediating the arterial baroreflex, particularly in heart failure (11,40,61), and sex differences in the regulation of the SNS (6,43,60). In addition, chloralose-urethane anesthesia has been shown to increase plasma osmolality in rats, particularly when administered intraperitoneally as was done in the current study, which likely affects the release of hormones, such as vasopressin, that may interact with sympathetic regulatory centers (23,32). Future investigations in conscious animals are required to further elucidate the effects of sex and ovarian hormones on changes to both resting renal SNA and the arterial baroreflex control of renal SNA following MI and the effect these have on cardiac function.…”

Section: R174 Ovarian Hormones Preserve Arterial Baroreflex Following MImentioning

confidence: 80%

Arterial baroreceptor reflex control of renal sympathetic nerve activity following chronic myocardial infarction in male, female, and ovariectomized female rats

Pinkham

Whalley

Guild

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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Pinkham MI, Whalley GA, Guild SJ, Malpas SC, Barrett CJ. Arterial baroreceptor reflex control of renal sympathetic nerve activity following chronic myocardial infarction in male, female, and ovariectomized female rats. Am J Physiol Regul Integr Comp Physiol 309: R169-R178, 2015. First published May 20, 2015 doi:10.1152/ajpregu.00026.2015.-There is controversy regarding whether the arterial baroreflex control of renal sympathetic nerve activity (SNA) in heart failure is altered. We investigated the impact of sex and ovarian hormones on changes in the arterial baroreflex control of renal SNA following a chronic myocardial infarction (MI). Renal SNA and arterial pressure were recorded in chloralose-urethane anesthetized male, female, and ovariectomized female (OVX) Wistar rats 6 -7 wk postsham or MI surgery. Animals were grouped according to MI size (sham, small and large MI). Ovary-intact females had a lower mortality rate post-MI (24%) compared with both males (38%) and OVX (50%) (P Ͻ 0.05). Males and OVX with large MI, but not small MI, displayed an impaired ability of the arterial baroreflex to inhibit renal SNA. As a result, the male large MI group (49 Ϯ 6 vs. 84 Ϯ 5% in male sham group) and OVX large MI group (37 Ϯ 3 vs. 75 Ϯ 5% in OVX sham group) displayed significantly reduced arterial baroreflex range of control of normalized renal SNA (P Ͻ 0.05). In ovary-intact females, arterial baroreflex control of normalized renal SNA was unchanged regardless of MI size. In males and OVX there was a significant, positive correlation between left ventricle (LV) ejection fraction and arterial baroreflex range of control of normalized renal SNA, but not absolute renal SNA, that was not evident in ovary-intact females. The current findings demonstrate that the arterial baroreflex control of renal SNA post-MI is preserved in ovary-intact females, and the state of left ventricular dysfunction significantly impacts on the changes in the arterial baroreflex post-MI.

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“…We used 1.0 g/kg of urethane because this dose has been shown to have little effect on cardiorespiratory function in rats (43,44). However, at this low dose, variations of the electroencephalographic (EEG) activity have been observed and can influence the HCVR (5).…”

Section: Surgical Proceduresmentioning

confidence: 99%

Neonatal stress and attenuation of the hypercapnic ventilatory response in adult male rats: the role of carotid chemoreceptors and baroreceptors

Dumont

Kinkead

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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-Neonatal maternal separation (NMS) is a form of stress that disrupts respiratory control development. Awake adult male rats previously subjected to NMS show a ventilatory response to hypercapnia (HCVR; FICO 2 ϭ 0.05) 47% lower than controls; however, the underlying mechanisms are unknown. To address this issue, we first tested the hypothesis that carotid bodies contribute to NMS-related attenuation of the HCVR by using carotid sinus nerve section or FIO 2 manipulation to maintain PaO 2 constant (iso-oxic) during hypercapnic hyperpnea. We then determined whether NMS-related augmentation of baroreflex sensitivity contributes to the reduced HCVR in NMS rats. Nitroprusside and phenylephrine injections were used to manipulate arterial blood pressure in both groups of rats. Pups subjected to NMS were separated from their mother 3 h/day from postnatal days 3 to 12. Control rats were undisturbed. At adulthood, rats were anesthetized [urethane (1g/kg) ϩ isoflurane (0.5%)], and diaphragmatic electromyogram (dEMG) was measured under baseline and hypercapnic conditions (PaCO 2 : 10 Torr above baseline). The relative minute activity response to hypercapnia of anesthetized NMS rats was 34% lower than controls. Maintaining PaO 2 constant during hypercapnia reversed this phenotype; the HCVR of NMS rats was 45% greater than controls. Although the decrease in breathing frequency during baroreflex activation was greater in NMS rats, the change observed within the range of pressure change observed during hypercapnia was minimal. We conclude that NMS-related changes in carotid body sensitivity to chemical stimuli and/or its central integration is a key mechanism in the attenuation of HCVR by NMS. control of breathing; development; stress; central integration IN HUMANS, RATS, AND NONHUMAN primates, the tactile, olfactory, and auditory stimuli provided by the mother to her offspring have a strong influence on central nervous system (CNS) development (17,18,38,40,50,56). Neonatal maternal separation (NMS) is a well-established, clinically relevant stress model that disrupts mother-offspring interactions to reproduce environmental conditions experienced by infants deprived from adequate parental stimulation due to special medical interventions associated with prematurity or inadequate maternal care (e.g., parental neglect, mother suffering from depression, orphanage) (14,38,50). Because this stress typically occurs during a critical period of development, NMS has long-lasting consequences on CNS development and affects maturation of basic homeostatic functions, such as the neuroendocrine regulation of stress responses (18, 61) and the respiratory control system (20,21,37).With regard to respiratory regulation, several recent reviews have highlighted the profound effects of excessive stimulation of chemosensory pathways (e.g., intermittent hypoxia, chronic hypoxia) on the developmental trajectory of the neural circuits that regulate breathing (2, 7). Depending on the severity of the stimulation protocols used, these models may activate ...

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Suitability of urethane anesthesia for physiopharmacological investigations. Part 3: Other systems and conclusions

Cited by 128 publications

References 61 publications

Expression of c-fos Protein in Rat Brain Elicited by Electrical and Chemical Stimulation of the Hypothalamic Paraventricular Nucleus

Expression of c-fos Protein in Rat Brain Elicited by Electrical and Chemical Stimulation of the Hypothalamic Paraventricular Nucleus

Arterial baroreceptor reflex control of renal sympathetic nerve activity following chronic myocardial infarction in male, female, and ovariectomized female rats

Neonatal stress and attenuation of the hypercapnic ventilatory response in adult male rats: the role of carotid chemoreceptors and baroreceptors

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