The long‐term impact of ovariectomy on ventilation and expression of phrenic long‐term facilitation in female rats

Age and the estrus cycle affect time-dependent respiratory responses to episodic hypoxia in female rats. Respiratory long-term facilitation (LTF) is enhanced in middle-aged vs. young female rats ( 72 ). We tested the hypothesis that phrenic and hypoglossal (XII) LTF are diminished in acyclic geriatric rats when fluctuating sex hormone levels no longer establish conditions that enhance LTF. Chronic intermittent hypoxia (CIH) enhances LTF ( 41 ); thus we further predicted that CIH would restore LTF in geriatric female rats. LTF was measured in young (3-4 mo) and geriatric (20-22 mo) female Sasco Sprague-Dawley rats and in a group of geriatric rats exposed to 1 wk of nocturnal CIH (11 vs. 21% O2 at 5-min intervals, 12 h/night). In anesthetized, paralyzed, vagotomized, and ventilated rats, time-dependent hypoxic phrenic and XII responses were assessed. The short-term hypoxic response was measured during the first of three 5-min episodes of isocapnic hypoxia (arterial Po2 35-45 Torr). LTF was assessed 15, 30, and 60 min postepisodic hypoxia. Phrenic and XII short-term hypoxic response was not different among groups, regardless of CIH treatment ( P > 0.05). LTF in geriatric female rats was smaller than previously reported for middle-aged rats but comparable to that in young female rats. CIH augmented phrenic and XII LTF to levels similar to those of middle-aged female rats without CIH ( P < 0.05). The magnitude of phrenic and XII LTF in all groups was inversely related to the ratio of progesterone to estradiol serum levels ( P < 0.05). Thus CIH and sex hormones influence the magnitude of LTF in geriatric female rats.

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Development of ventilatory long-term facilitation is dependent on estrous cycle stage in adult female rats

Respiratory Physiology & Neurobiology ◽

10.1016/j.resp.2019.02.006 ◽

2019 ◽

Vol 264 ◽

pp. 1-7

Author(s):

Danielle McIntosh ◽

Brendan J. Dougherty

Keyword(s):

Estrous Cycle ◽

Adult Female ◽

Female Rats ◽

Estrous Cycle Stage ◽

Long Term Facilitation

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Long-term impact of neonatal injury in male and female rats: Sex differences, mechanisms and clinical implications

Frontiers in Neuroendocrinology ◽

10.1016/j.yfrne.2010.02.001 ◽

2010 ◽

Vol 31 (2) ◽

pp. 193-202 ◽

Cited By ~ 40

Author(s):

Jamie L. LaPrairie ◽

Anne Z. Murphy

Keyword(s):

Sex Differences ◽

Female Rats ◽

Clinical Implications ◽

Male And Female ◽

Male And Female Rats ◽

Neonatal Injury ◽

Long Term Impact

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Hypoxic and hypercapnic ventilatory responses in aging male vs. aging female rats

Journal of Applied Physiology ◽

10.1152/japplphysiol.90802.2008 ◽

2009 ◽

Vol 106 (5) ◽

pp. 1522-1528 ◽

Cited By ~ 27

Author(s):

J. M. Wenninger ◽

E. B. Olson ◽

C. J. Cotter ◽

C. F. Thomas ◽

M. Behan

Keyword(s):

Sex Hormones ◽

Middle Age ◽

Minute Ventilation ◽

Female Rats ◽

Male Rats ◽

Hormone Levels ◽

Ventilatory Responses ◽

Age Related ◽

Long Term Facilitation

It is clear that sex hormones impact ventilation. While the effects of the menstrual cycle, pregnancy, testosterone, and progesterone on resting ventilation have been well documented, effects of sex hormones on the hypoxic (HVR) and hypercapnic ventilatory responses (HCVR) are inconclusive. In addition, in no study have systemic sex steroid hormone levels been measured. Age and sex differences in long-term facilitation in response to episodic hypoxia were found in anesthetized rats. The purpose of the present study was to assess the effects of sex and age [young, 3–4 mo; middle age, 12–13 mo; and old, >20 mo] on the HVR and the HCVR of awake rats relative to systemic hormone levels. Based on findings from long-term facilitation studies, we hypothesized that the HVR would be influenced by both sex and age. We found no age-related changes in the HVR or HCVR. However, female rats have a greater HVR than male rats at old age, and at middle age female rats have a greater HCVR than male rats. Additionally, we found no correlation between the minute ventilation/oxygen consumption and the progesterone-to-estrogen ratio during hypoxia or hypercapnia. However, changes in ventilatory responses with age were not similar between the sexes. Thus it is critical to take sex, age, estrous cycle stage, and systemic hormone levels into consideration when conducting and reporting studies on respiratory control.

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Crisis Phones - Suicide Prevention Versus Suggestion/Contagion Effects

Crisis ◽

10.1027/0227-5910/a000313 ◽

2015 ◽

Vol 36 (3) ◽

pp. 220-224 ◽

Cited By ~ 3

Author(s):

Steven Stack

Keyword(s):

Suicide Prevention ◽

Contagion Effects ◽

Long Term Impact

Abstract. Background: There has been no systematic work on the short- or long-term impact of the installation of crisis phones on suicides from bridges. The present study addresses this issue. Method: Data refer to 219 suicides from 1954 through 2013 on the Skyway Bridge in St. Petersburg, Florida. Six crisis phones with signs were installed in July 1999. Results: In the first decade after installation, the phones were used by 27 suicidal persons and credited with preventing 26 or 2.6 suicides a year. However, the net suicide count increased from 48 in the 13 years before installation of phones to 106 the following 13 years or by 4.5 additional suicides/year (t =3.512, p < .001). Conclusion: Although the phones prevented some suicides, there was a net increase after installation. The findings are interpreted with reference to suggestion/contagion effects including the emergence of a controversial bridge suicide blog.

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