Age specific effect of MK-801 on hypoxic body temperature regulation in rats

Baig, Mirza Shafiulla; Joseph, Vincent

doi:10.1016/j.resp.2007.09.008

Cited by 5 publications

(2 citation statements)

References 33 publications

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“…Our finding that a 5 mg/kg dose of morphine elicited a minor sustained hyperthermia of ≈ 0.4 °C is consistent with findings from other laboratories [34,35]. Exposure of VEH rats to 15 min episodes of hypoxia (10% O 2 , 90% N 2 ) elicited minor decreases in B T of 0.4 °C, consistent with evidence that exposure of rats to 10–12% O 2 for 15 min elicits no effects [36] or a decrease of ≈ 0.5°C [37,38]. Since each episode of hypoxia elicited very similar arithmetic falls in B T in VEH and MOR rats, it appears that despite elevating B T , morphine does not impair the metabolic processes that cause hypoxia-induced hypothermia.…”

Section: Discussionsupporting

confidence: 89%

Morphine has latent deleterious effects on the ventilatory responses to a hypoxic challenge*

May¹,

Gruber²,

Discala³

et al. 2013

OJMIP

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The aim of this study was to determine whether morphine depresses the ventilatory responses elicited by a hypoxic challenge (10% O2, 90% N2) in conscious rats at a time when the effects of morphine on arterial blood gas (ABG) chemistry, Alveolar-arterial (A-a) gradient and minute ventilation (VM) had completely subsided. In vehicle-treated rats, each episode of hypoxia stimulated ventilatory function and the responses generally subsided during each normoxic period. Morphine (5 mg/kg, i.v.) induced an array of depressant effects on ABG chemistry, A-a gradient and VM (via decreases in tidal volume). Despite resolution of these morphine-induced effects, the first episode of hypoxia elicited substantially smaller increases in VM than in vehicle-treated rats, due mainly to smaller increases in frequency of breathing. The pattern of ventilatory responses during subsequent episodes of hypoxia and normoxia changed substantially in morphine-treated rats. It is evident that morphine has latent deleterious effects on ventilatory responses elicited by hypoxic challenge.

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Section: Discussionsupporting

confidence: 89%

Morphine has latent deleterious effects on the ventilatory responses to a hypoxic challenge*

May¹,

Gruber²,

Discala³

et al. 2013

OJMIP

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“…The differences between our results and those reported previously on cell cultures (Bell et al 2007;Guzy et al 2005;Taylor and Peers 1999) could arise from differences in the experimental preparations such as cell culture versus intact animals as well as propagating phenotype of cells used in earlier studies versus the nonpropagating nature of native chromaffin cells used in this study. Hypobaric hypoxia can lower the metabolism and body temperature in rat pups (Baig and Joseph 2008). Alternatively, the reduced CA secretion might be secondary to the effects of SH on body metabolism, resulting in reduced tyrosine hydroxylase activity leading to decreased CA synthesis.…”

Section: Sh Attenuates Hypoxia-evoked Ca Secretionmentioning

confidence: 99%

Neonatal Intermittent Hypoxia Leads to Long-Lasting Facilitation of Acute Hypoxia-Evoked Catecholamine Secretion From Rat Chromaffin Cells

Souvannakitti

Kumar²,

Fox³

et al. 2009

Journal of Neurophysiology

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Souvannakitti D, Kumar GK, Fox A, Prabhakar NR. Neonatal intermittent hypoxia leads to long-lasting facilitation of acute hypoxia-evoked catecholamine secretion from rat chromaffin cells. J Neurophysiol 101: 2837-2846, 2009. First published April 1, 2009 doi:10.1152/jn.00036.2009. The objective of the present study was to examine the effects of intermittent hypoxia (IH) and sustained hypoxia (SH) on hypoxia-evoked catecholamine (CA) secretion from chromaffin cells in neonatal rats and assess the underlying mechanism(s). Experiments were performed on rat pups exposed to either IH (15-s hypoxia/5-min normoxia; 8 h/day) or SH (hypobaric hypoxia, 0.4 atm) or normoxia (controls) from P0 to P5. IH treatment facilitated hypoxia-evoked CA secretion and elevations in the intracellular calcium ion concentration ([Ca 2ϩ ] i ) and these responses were attenuated, but not abolished, by treatments designed to eliminate Ca 2ϩ flux into cells (Ca 2ϩ -free medium or Cd 2ϩ ), indicating that intracellular Ca 2ϩ stores were augmented by IH. Norepinephrine (NE) and epinephrine (E) levels of adrenal medullae were elevated in IH-treated pups. IH treatment increased reactive oxygen species (ROS) production in adrenal medullae and antioxidant treatment prevented IH-induced facilitation of CA secretion, elevations in [Ca 2ϩ ] i by hypoxia, and the up-regulation of NE and E. The effects of neonatal IH treatment on hypoxia-induced CA secretion and elevation in [Ca 2ϩ ] i , CA, and ROS levels persisted in rats reared under normoxia for Ͼ30 days. In striking contrast, chromaffin cells from SH-treated animals exhibited attenuated hypoxia-evoked CA secretion. In SH-treated cells hypoxiaevoked elevations in [Ca 2ϩ ] i , NE and E contents, and ROS levels were comparable with controls. These observations demonstrate that: 1) neonatal IH and SH evoke opposite effects on hypoxia-evoked CA secretion from chromaffin cells, 2) ROS signaling mediates the faciltatory effects of IH, and 3) the effects of neonatal IH on chromaffin cells persist into adult life. I N T R O D U C T I O NCatecholamine (CA) secretion from the adrenal medulla is critical for maintaining homeostasis under a variety of stress conditions including hypoxia (Lagercrantz and Bistoletti 1977;Seidler and Slotkin 1985). In adult animals, hypoxia-evoked CA secretion from chromaffin cells is neurogenic and requires activation of the sympathetic nervous system (Seidler and Slotkin 1986;Yokotani et al. 2002). In neonates the sympathetic nervous system is not well developed (Seidler and Slotkin 1985). In this case, hypoxia still evokes CA secretion from neonatal chromaffin cells by directly affecting their excitability and elevating intracellular calcium ion concentration ( [Ca 2ϩ ] i ; Takeuchi et al. 2001;Thompson et al. 1997). These studies demonstrate that neonatal chromaffin cells have the ability to sense acute hypoxia similar to the glomus cells of the carotid bodies of adult mammals.Chronic perturbations in environmental O 2 profoundly influence carotid body sensory respo...

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Case Study: Developmental Physiology at High Altitude

Jochmans-Lemoine

Joseph

2018

Development and Environment

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Age specific effect of MK-801 on hypoxic body temperature regulation in rats

Cited by 5 publications

References 33 publications

Morphine has latent deleterious effects on the ventilatory responses to a hypoxic challenge*

Morphine has latent deleterious effects on the ventilatory responses to a hypoxic challenge*

Neonatal Intermittent Hypoxia Leads to Long-Lasting Facilitation of Acute Hypoxia-Evoked Catecholamine Secretion From Rat Chromaffin Cells

Case Study: Developmental Physiology at High Altitude

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