Estrogen's attenuating effect on the exercise pressor reflex is more opioid dependent in gonadally intact than in ovariectomized female cats

Petra M. Schmitt, Marc Kaufman

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Using gonadally intact female cats, we showed previously that estrogen, applied topically to the spinal cord, attenuated the exercise pressor reflex. Although the mechanism by which estrogen exerted its attenuating effect is unknown, this steroid hormone has been shown to influence spinal opioid pathways, which in turn have been implicated in the regulation of the exercise pressor reflex. These findings prompted us to test the hypothesis that opioids mediate the attenuating effect of estrogen on the exercise pressor reflex in both gonadally intact female and ovariectomized cats. We therefore applied 200 μl of 17β-estradiol (0.01 μg/ml) with and without the addition of 1,000 μg naloxone, a μ- and δ-opioid antagonist, to a spinal well covering the L6-S1 spinal cord in decerebrated female cats that were either gonadally intact or ovariectomized. The exercise pressor reflex was evoked by electrical stimulation of the L7 or S 1 ventral root, a maneuver that caused the hindlimb muscles to contract statically. We found that, in gonadally intact cats, the attenuating effect of estrogen was more pronounced than that in ovariectomized cats. We also found that, in gonadally intact female cats, naloxone partly reversed the attenuation of the pressor response to static contraction caused by spinal estrogen application. For example, in intact cats, the pressor response to contraction before estrogen application averaged 39 ± 4 mmHg (n = 10), whereas the pressor response 60 min afterward averaged only 18 ± 4 mmHg (P < 0.05). In contrast, the pressor response to contraction before estrogen and naloxone application averaged 33 ± 5 mmHg (n = 11), whereas afterward it averaged 27 ± 6 mmHg (P < 0.05). In ovariectomized cats, naloxone was less effective in reversing the attenuating effect of estrogen on the exercise pressor reflex.

Original languageEnglish (US)
Pages (from-to)633-639
Number of pages7
JournalJournal of applied physiology
Volume98
Issue number2
DOIs
StatePublished - Feb 1 2005

Fingerprint

Opioid Analgesics
Reflex
Estrogens
Cats
Naloxone
Spinal Cord
Narcotic Antagonists
Spinal Nerve Roots
Hindlimb
Electric Stimulation
Estradiol
Steroids
Hormones
Muscles

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

@article{2b08a766b23042a387b2e7756f1ba65e,
title = "Estrogen's attenuating effect on the exercise pressor reflex is more opioid dependent in gonadally intact than in ovariectomized female cats",
abstract = "Using gonadally intact female cats, we showed previously that estrogen, applied topically to the spinal cord, attenuated the exercise pressor reflex. Although the mechanism by which estrogen exerted its attenuating effect is unknown, this steroid hormone has been shown to influence spinal opioid pathways, which in turn have been implicated in the regulation of the exercise pressor reflex. These findings prompted us to test the hypothesis that opioids mediate the attenuating effect of estrogen on the exercise pressor reflex in both gonadally intact female and ovariectomized cats. We therefore applied 200 μl of 17β-estradiol (0.01 μg/ml) with and without the addition of 1,000 μg naloxone, a μ- and δ-opioid antagonist, to a spinal well covering the L6-S1 spinal cord in decerebrated female cats that were either gonadally intact or ovariectomized. The exercise pressor reflex was evoked by electrical stimulation of the L7 or S 1 ventral root, a maneuver that caused the hindlimb muscles to contract statically. We found that, in gonadally intact cats, the attenuating effect of estrogen was more pronounced than that in ovariectomized cats. We also found that, in gonadally intact female cats, naloxone partly reversed the attenuation of the pressor response to static contraction caused by spinal estrogen application. For example, in intact cats, the pressor response to contraction before estrogen application averaged 39 ± 4 mmHg (n = 10), whereas the pressor response 60 min afterward averaged only 18 ± 4 mmHg (P < 0.05). In contrast, the pressor response to contraction before estrogen and naloxone application averaged 33 ± 5 mmHg (n = 11), whereas afterward it averaged 27 ± 6 mmHg (P < 0.05). In ovariectomized cats, naloxone was less effective in reversing the attenuating effect of estrogen on the exercise pressor reflex.",
author = "Schmitt, {Petra M.} and Marc Kaufman",
year = "2005",
month = "2",
day = "1",
doi = "10.1152/japplphysiol.00788.2004",
language = "English (US)",
volume = "98",
pages = "633--639",
journal = "Journal of Applied Physiology",
issn = "8750-7587",
publisher = "American Physiological Society",
number = "2",

}

TY - JOUR

T1 - Estrogen's attenuating effect on the exercise pressor reflex is more opioid dependent in gonadally intact than in ovariectomized female cats

AU - Schmitt, Petra M.

AU - Kaufman, Marc

PY - 2005/2/1

Y1 - 2005/2/1

N2 - Using gonadally intact female cats, we showed previously that estrogen, applied topically to the spinal cord, attenuated the exercise pressor reflex. Although the mechanism by which estrogen exerted its attenuating effect is unknown, this steroid hormone has been shown to influence spinal opioid pathways, which in turn have been implicated in the regulation of the exercise pressor reflex. These findings prompted us to test the hypothesis that opioids mediate the attenuating effect of estrogen on the exercise pressor reflex in both gonadally intact female and ovariectomized cats. We therefore applied 200 μl of 17β-estradiol (0.01 μg/ml) with and without the addition of 1,000 μg naloxone, a μ- and δ-opioid antagonist, to a spinal well covering the L6-S1 spinal cord in decerebrated female cats that were either gonadally intact or ovariectomized. The exercise pressor reflex was evoked by electrical stimulation of the L7 or S 1 ventral root, a maneuver that caused the hindlimb muscles to contract statically. We found that, in gonadally intact cats, the attenuating effect of estrogen was more pronounced than that in ovariectomized cats. We also found that, in gonadally intact female cats, naloxone partly reversed the attenuation of the pressor response to static contraction caused by spinal estrogen application. For example, in intact cats, the pressor response to contraction before estrogen application averaged 39 ± 4 mmHg (n = 10), whereas the pressor response 60 min afterward averaged only 18 ± 4 mmHg (P < 0.05). In contrast, the pressor response to contraction before estrogen and naloxone application averaged 33 ± 5 mmHg (n = 11), whereas afterward it averaged 27 ± 6 mmHg (P < 0.05). In ovariectomized cats, naloxone was less effective in reversing the attenuating effect of estrogen on the exercise pressor reflex.

AB - Using gonadally intact female cats, we showed previously that estrogen, applied topically to the spinal cord, attenuated the exercise pressor reflex. Although the mechanism by which estrogen exerted its attenuating effect is unknown, this steroid hormone has been shown to influence spinal opioid pathways, which in turn have been implicated in the regulation of the exercise pressor reflex. These findings prompted us to test the hypothesis that opioids mediate the attenuating effect of estrogen on the exercise pressor reflex in both gonadally intact female and ovariectomized cats. We therefore applied 200 μl of 17β-estradiol (0.01 μg/ml) with and without the addition of 1,000 μg naloxone, a μ- and δ-opioid antagonist, to a spinal well covering the L6-S1 spinal cord in decerebrated female cats that were either gonadally intact or ovariectomized. The exercise pressor reflex was evoked by electrical stimulation of the L7 or S 1 ventral root, a maneuver that caused the hindlimb muscles to contract statically. We found that, in gonadally intact cats, the attenuating effect of estrogen was more pronounced than that in ovariectomized cats. We also found that, in gonadally intact female cats, naloxone partly reversed the attenuation of the pressor response to static contraction caused by spinal estrogen application. For example, in intact cats, the pressor response to contraction before estrogen application averaged 39 ± 4 mmHg (n = 10), whereas the pressor response 60 min afterward averaged only 18 ± 4 mmHg (P < 0.05). In contrast, the pressor response to contraction before estrogen and naloxone application averaged 33 ± 5 mmHg (n = 11), whereas afterward it averaged 27 ± 6 mmHg (P < 0.05). In ovariectomized cats, naloxone was less effective in reversing the attenuating effect of estrogen on the exercise pressor reflex.

UR - http://www.scopus.com/inward/record.url?scp=12344303594&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=12344303594&partnerID=8YFLogxK

U2 - 10.1152/japplphysiol.00788.2004

DO - 10.1152/japplphysiol.00788.2004

M3 - Article

C2 - 15448125

AN - SCOPUS:12344303594

VL - 98

SP - 633

EP - 639

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 8750-7587

IS - 2

ER -