Using vaginal wall impedance to determine estrous cycle phase in Lewis rats

Jaramillo, Luis Fernando; Balcázar, Ignacio Briceño; Durán, Camilo

doi:10.1038/laban0512-122

Cited by 23 publications

(19 citation statements)

References 15 publications

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“…Measurements of vaginal membrane resistance have been effectively used for optimizing reproduction in large species (46,47) years before it was first used in small laboratory animals (48). Trans-specimen properties of this method rely on the sex hormoneYdependent changes of vaginal membrane composition leading to alterations in the membrane's electrical resistance; i.e., cycle phases are identified by characteristic oscillation of impedance values.…”

Section: Discussionmentioning

confidence: 99%

Estrus Cycle Status Defined by Vaginal Cytology Does Not Correspond to Fluctuations of Circulating Estrogens in Female Mice

Weixelbaumer¹,

Drechsler²,

Wehrenpfennig³

et al. 2014

Shock

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Gender-oriented studies in shock, trauma, and/or sepsis require accurate monitoring of hormonal fluctuations as estrogens may influence various end points. Yet, monitoring is challenging in small laboratory animals: e.g., despite its subjectivity, vaginal smears are the major method for determination of estrus cycle phases in mice. Using female mice of different age, we aimed to (a) characterize general age-related changes in systemic estrogens and (b) examine the utility of determination of the estrus cycle by vaginal smears and/or impedance simultaneously comparing them with oscillation of systemic estrogens. In this study, 3-, 15-, and 20-month-old mice underwent vaginal smear and impedance examination each morning for 22 days. Ten hours after each morning checkup, feces were collected, and a second vaginal smear performed. Blood was collected on days 15 and 22. In 3-month-old females, estrus (by smears) was three times more frequent than in older mice, but mean concentrations of plasma and fecal estrogens never decreased with age. Collectively (not individually) plotted fecal estrogens values increased in the proestrus/estrus interphase (by smears) in 3-month-old mice only. Impedance typically peaked (4.5 Ω in 3-month-old mice) in the estrus phase, and only the prediction of estrus (highest area under the curve = 0.87 in 3-month-old) but not of other phases was possible. Regardless of age, individual cycle phase (by smears) never correlated with corresponding fecal estrogens, and estrus could not be predicted. In conclusion, while the fecal estrogens oscillation and frequency of estrus phase were affected by age, the systemic hormone release persisted. In mice, vaginal cytology did not reflect changes of systemic (fecal) estrogens, whereas impedance accurately identified estrus. The flaws and advantages of the examined monitoring methods should be considered in the design of future shock studies.

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Section: Discussionmentioning

confidence: 99%

Estrus Cycle Status Defined by Vaginal Cytology Does Not Correspond to Fluctuations of Circulating Estrogens in Female Mice

Weixelbaumer¹,

Drechsler²,

Wehrenpfennig³

et al. 2014

Shock

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“…At a weight threshold of 230 g (∼3–4 months old), dams were assessed daily for proestrous via vaginal electrical impedance (≥4.0 kΩ) using an EC40 oestrous cycle monitor (Fine Science Tools, Foster City, CA, USA) as previously described (Jaramillo et al . ). Once in proestrous, dams were housed with a proven stud male for the first 5 h of the dark cycle (12.00–17.00 h) and successful mating confirmed by the presence of a seminal plug, with the following morning designated as embryonic day (E) 0.5.…”

Section: Methodsmentioning

confidence: 97%

Prenatal alcohol exposure programmes offspring disease: insulin resistance in adult males in a rat model of acute exposure

Nguyen

Steane

Moritz

et al. 2019

The Journal of Physiology

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Key points Prenatal alcohol exposure has the potential to affect fetal development and programme chronic disease in offspring. Previous preclinical models typically use high, chronic doses of alcohol throughout pregnancy to examine effects on offspring, particularly on the brain and behaviour. In this study we use a rat model of moderate, acute, prenatal alcohol exposure to determine if this can be detrimental to maintenance of glucose homeostasis in adolescent and adult offspring. Although female offspring were relatively unaffected, there was evidence of insulin resistance in 6‐month‐old male offspring exposed to prenatal alcohol, suggestive of a pre‐diabetic state. This result suggests that even a relatively low‐dose, acute exposure to alcohol during pregnancy can still programme metabolic dysfunction in a sex‐specific manner. Abstract Alcohol consumption is highly prevalent amongst women of reproductive age. Given that approximately 50% of pregnancies are unplanned, alcohol has the potential to affect fetal development and programme chronic disease in offspring. We examined the effect of an acute but moderate prenatal alcohol exposure (PAE) on glucose metabolism, lipid levels and dietary preference in adolescent and/or adult rat offspring. Pregnant Sprague–Dawley rats received an oral gavage of ethanol (1 g kg−1 maternal body weight, n = 9 dams) or an equivalent volume of saline (control, n = 8 dams) at embryonic days 13.5 and 14.5. PAE resulted in a blood alcohol concentration of 0.05–0.06% 1 h post‐gavage in dams. Fasting blood glucose concentration was not affected by PAE in offspring at any age, nor were blood glucose levels during a glucose tolerance test (GTT) in 6‐month‐old offspring (P > 0.5). However, there was evidence of insulin resistance in PAE male offspring at 6 months of age, with significantly elevated fasting plasma insulin (P = 0.001), a tendency for increased first phase insulin secretion during the GTT and impaired glucose clearance following an insulin challenge (P = 0.007). This was accompanied by modest alterations in protein kinase B (AKT) signalling in adipose tissue. PAE also resulted in reduced calorie consumption by offspring compared to controls (P = 0.04). These data suggest that a relatively low‐level, acute PAE programmes metabolic dysfunction in offspring in a sex‐specific manner. These results highlight that alcohol consumption during pregnancy has the potential to affect the long‐term health of offspring.

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“…In the present study ovarian cycle was induced in previously anovulatory virgin adult mice (15–20 week-old) by a single exposure to male bedding, and monitored by means of vaginal impedance measurements and vaginal smears cytological analysis, as previously described (Ramos et al, 2001; Maguire et al, 2005; Jaramillo et al, 2012; Cushman et al, 2014). Briefly, vaginal impedance was measured daily (Estrus cycle monitor EC40, Fine Science Tools).…”

Section: Methodsmentioning

confidence: 99%

Ovarian cycle-linked plasticity of Î´-GABAA receptor subunits in hippocampal interneurons affects Î³ oscillations in vivo

Barth

Ferando

Módy

2014

Front. Cell. Neurosci.

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GABAA receptors containing δ subunits (δ-GABAARs) are GABA-gated ion channels with extra- and perisynaptic localization, strong sensitivity to neurosteroids (NS), and a high degree of plasticity. In selective brain regions they are expressed on specific principal cells and interneurons (INs), and generate a tonic conductance that controls neuronal excitability and oscillations. Plasticity of δ-GABAARs in principal cells has been described during states of altered NS synthesis including acute stress, puberty, ovarian cycle, pregnancy and the postpartum period, with direct consequences on neuronal excitability and network dynamics. The defining network events implicated in cognitive function, memory formation and encoding are γ oscillations (30–120 Hz), a well-timed loop of excitation and inhibition between principal cells and PV-expressing INs (PV + INs). The δ-GABAARs of INs can modify γ oscillations, and a lower expression of δ-GABAARs on INs during pregnancy alters γ frequency recorded in vitro. The ovarian cycle is another physiological event with large fluctuations in NS levels and δ-GABAARs. Stages of the cycle are paralleled by swings in memory performance, cognitive function, and mood in both humans and rodents. Here we show δ-GABAARs changes during the mouse ovarian cycle in hippocampal cell types, with enhanced expression during diestrus in principal cells and specific INs. The plasticity of δ-GABAARs on PV-INs decreases the magnitude of γ oscillations continuously recorded in area CA1 throughout several days in vivo during diestrus and increases it during estrus. Such recurring changes in γ magnitude were not observed in non-cycling wild-type (WT) females, cycling females lacking δ-GABAARs only on PV-INs (PV-Gabrd-/-), and in male mice during a time course equivalent to the ovarian cycle. Our findings may explain the impaired memory and cognitive performance experienced by women with premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD).

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Using vaginal wall impedance to determine estrous cycle phase in Lewis rats

Cited by 23 publications

References 15 publications

Estrus Cycle Status Defined by Vaginal Cytology Does Not Correspond to Fluctuations of Circulating Estrogens in Female Mice

Estrus Cycle Status Defined by Vaginal Cytology Does Not Correspond to Fluctuations of Circulating Estrogens in Female Mice

Prenatal alcohol exposure programmes offspring disease: insulin resistance in adult males in a rat model of acute exposure

Ovarian cycle-linked plasticity of Î´-GABAA receptor subunits in hippocampal interneurons affects Î³ oscillations in vivo

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