Suitability of urethane anesthesia for physiopharmacological investigations in various systems. Part 2: Cardiovascular system

Maggi, Carlo Alberto; Meli, Alberto

doi:10.1007/bf01942510

Cited by 201 publications

(90 citation statements)

References 45 publications

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“…Oscillatory activity under urethane anesthesia in mice Urethane, a carcinogenic substance, is favored for acute in vivo electrophysiological experiments because it induces long-lasting steady level of anesthesia with muscle relaxation (Maggi and Meli, 1986a) and minimally affects the autonomic and cardiovascular systems (Maggi and Meli, 1986b;Hara and Harris, 2002;Janssen et al, 2004). Most of our knowledge about the specific neurons involved in various brain oscillations comes from urethane anesthetized rats (Klausberger and Somogyi, 2008).…”

Section: Discussionmentioning

confidence: 99%

Changes in Hippocampal Neuronal Activity During and After Unilateral Selective Hippocampal IschemiaIn Vivo

Barth¹,

Módy²

2011

J. Neurosci.

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The hippocampal formation is one of the brain regions most sensitive to ischemic damage. However, there are no studies about changes in hippocampal neuronal activity during and after a selective unilateral hippocampal ischemia. We developed a novel unilateral cerebrovascular ischemia model in mice that selectively shuts down blood supply to the ipsilateral hippocampal formation. Using a modified version of the photothrombotic method, we stereotaxically targeted the initial ascending part of the longitudinal hippocampal artery in urethane anesthetized and rose bengal-injected mice. To block blood flow in the targeted artery, we photoactivated the rose bengal by illuminating the longitudinal hippocampal artery through an optical fiber inserted into the brain. In vivo field potential recordings in the CA1 region of the hippocampus before, during and after the induction of ischemia demonstrated a high-frequency discharge (HFD) reaching frequencies of Ͼ300 Hz and lasting 7-24 s during the illumination consistent with a massive synchronous neuronal activity. The HFD was invariably followed by a DC voltage shift and a decreased activity at both low (30 -57 Hz)-and high (63-119 Hz)-gamma frequencies. This decrease in gamma activity lasted for the entire duration of the recordings (ϳ160 min) following ischemia. The contralateral hippocampus displayed HFDs but with different frequency spectra and without DC voltage shifts or long-lasting decreases in gamma oscillations. Our findings reveal for the first time the acute effects of unilateral hippocampal ischemia on ensemble hippocampal neuronal activities.

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Section: Discussionmentioning

confidence: 99%

Changes in Hippocampal Neuronal Activity During and After Unilateral Selective Hippocampal IschemiaIn Vivo

Barth¹,

Módy²

2011

J. Neurosci.

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“…Urethane anesthesia is commonly used for cardio-respiratory studies attributable to limited effects on cardiovascular, respiratory, and spinal reflexes, and its long-lasting stable sedative level (Maggi and Meli, 1986;Teppema and Baby, 2011). Urethane is a nontypical general anesthetic because it has only moderate effects on excitatory or inhibitory amino acid neurotransmission (Hara and Harris, 2002).…”

Section: State-dependent Modulation Of Respiratory Activitymentioning

confidence: 99%

State-Dependent Modulation of Breathing in Urethane-Anesthetized Rats

et al. 2012

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Respiratory activity is most fragile during sleep, in particular during paradoxical [or rapid eye movement (REM)] sleep and sleep state transitions. Rats are commonly used to study respiratory neuromodulation, but rodent sleep is characterized by a highly fragmented sleep pattern, thus making it very challenging to examine different sleep states and potential pharmacological manipulations within them. Sleep-like brain-state alternations occur in rats under urethane anesthesia and may be an effective and efficient model for sleep itself. The present study assessed state-dependent changes in breathing and respiratory muscle modulation under urethane anesthesia to determine their similarity to those occurring during natural sleep. Rats were anesthetized with urethane and respiratory airflow, as well as electromyographic activity in respiratory muscles were recorded in combination with local field potentials in neocortex and hippocampus to determine how breathing pattern and muscle activity are modulated with brain state. Measurements were made in normoxic, hypoxic, and hypercapnic conditions. Results were compared with recordings made from rats during natural sleep. Brain-state alternations under urethane anesthesia were closely correlated with changes in breathing rate and variability and with modulation of respiratory muscle tone. These changes closely mimicked those observed in natural sleep. Of great interest was that, during both REM and REM-like states, genioglossus muscle activity was strongly depressed and abdominal muscle activity showed potent expiratory modulation. We demonstrate that, in urethane-anesthetized rats, respiratory airflow and muscle activity are closely correlated with brain-state transitions and parallel those shown in natural sleep, providing a useful model to systematically study sleep-related changes in respiratory control.

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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 in various systems. Part 2: Cardiovascular system

Cited by 201 publications

References 45 publications

Changes in Hippocampal Neuronal Activity During and After Unilateral Selective Hippocampal IschemiaIn Vivo

Changes in Hippocampal Neuronal Activity During and After Unilateral Selective Hippocampal IschemiaIn Vivo

State-Dependent Modulation of Breathing in Urethane-Anesthetized 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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