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Sustained inhibition of rat myometrial gap junctions and contractions by lindane.

Loch-Caruso RK, Criswell KA, Grindatti CM, Brant KA - Reprod. Biol. Endocrinol. (2003)

Bottom Line: Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus.To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20) rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane.After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure.

View Article: PubMed Central - HTML - PubMed

Affiliation: Toxicology Program, Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA. rlc@umich.edu

ABSTRACT

Background: Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus. Lindane, a pesticide used in the human and veterinary treatment of scabies and lice as well as in agricultural applications, inhibits uterine contractions in vitro, inhibits myometrial gap junctions, and has been associated with prolonged gestation length in rats. The aim of the present study was to investigate whether brief exposures to lindane would elicit sustained inhibition of rat uterine contractile activity and myometrial gap junction intercellular communication.

Methods: To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20) rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane. Lucifer yellow dye transfer between myometrial cells in culture was used to monitor gap junction intercellular communication.

Results: During a 1-h exposure, 10 micro M and 100 micro M lindane decreased peak force and frequency of uterine contraction but 1 micro M lindane did not. After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure. In cultured myometrial myocytes, significant sustained inhibition of Lucifer yellow dye transfer was observed 24 h after lindane exposures as brief as 10 min and as low as 0.1 micro M lindane.

Conclusion: Brief in vitro exposures to lindane have long-term effects on myometrial functions that are necessary for parturition, inhibiting spontaneous phasic contractions in late gestation rat uterus and gap junction intercellular communication in myometrial cell cultures.

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Sustained inhibition of Lucifer yellow dye transfer following lindane exposures of different durations. Lucifer yellow dye transfer between myometrial cells was inhibited 24 h after initiating 10-min, 1-h or 24-h treatments with ethanol (solvent control) or 100 μM lindane. ANOVA, p ≤ 0.0001. Mean values ± S.E.M. are shown (n = 5–8 culture dishes; 7–22 cells were injected per dish). Vertical bars with different letters have means that are significantly different from each other in pair-wise comparisons (Student-Newman-Keuls, p ≤ 0.05).
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Figure 7: Sustained inhibition of Lucifer yellow dye transfer following lindane exposures of different durations. Lucifer yellow dye transfer between myometrial cells was inhibited 24 h after initiating 10-min, 1-h or 24-h treatments with ethanol (solvent control) or 100 μM lindane. ANOVA, p ≤ 0.0001. Mean values ± S.E.M. are shown (n = 5–8 culture dishes; 7–22 cells were injected per dish). Vertical bars with different letters have means that are significantly different from each other in pair-wise comparisons (Student-Newman-Keuls, p ≤ 0.05).

Mentions: Subsequent experiments determined the effect of exposure duration on sustained inhibition of dye transfer by lindane. Lindane decreased dye transfer to similar extents regardless of whether the duration of exposure was 10 min, 1 h or 24 h (Fig. 7, ANOVA, p ≤ 0.0001). The decrease in dye transfer was statistically greater in the cultures exposed to lindane for 1 h or 24 h compared with cultures exposed for 10 min, although the magnitude of the difference was modest (p ≤ 0.05). There were no significant differences in dye transfer between cultures exposed to lindane for 1 h or 24 h. These results show that an exposure as brief as 10 min to 100 μM lindane was sufficient to inhibit Lucifer yellow dye transfer 24 h later.


Sustained inhibition of rat myometrial gap junctions and contractions by lindane.

Loch-Caruso RK, Criswell KA, Grindatti CM, Brant KA - Reprod. Biol. Endocrinol. (2003)

Sustained inhibition of Lucifer yellow dye transfer following lindane exposures of different durations. Lucifer yellow dye transfer between myometrial cells was inhibited 24 h after initiating 10-min, 1-h or 24-h treatments with ethanol (solvent control) or 100 μM lindane. ANOVA, p ≤ 0.0001. Mean values ± S.E.M. are shown (n = 5–8 culture dishes; 7–22 cells were injected per dish). Vertical bars with different letters have means that are significantly different from each other in pair-wise comparisons (Student-Newman-Keuls, p ≤ 0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC222921&req=5

Figure 7: Sustained inhibition of Lucifer yellow dye transfer following lindane exposures of different durations. Lucifer yellow dye transfer between myometrial cells was inhibited 24 h after initiating 10-min, 1-h or 24-h treatments with ethanol (solvent control) or 100 μM lindane. ANOVA, p ≤ 0.0001. Mean values ± S.E.M. are shown (n = 5–8 culture dishes; 7–22 cells were injected per dish). Vertical bars with different letters have means that are significantly different from each other in pair-wise comparisons (Student-Newman-Keuls, p ≤ 0.05).
Mentions: Subsequent experiments determined the effect of exposure duration on sustained inhibition of dye transfer by lindane. Lindane decreased dye transfer to similar extents regardless of whether the duration of exposure was 10 min, 1 h or 24 h (Fig. 7, ANOVA, p ≤ 0.0001). The decrease in dye transfer was statistically greater in the cultures exposed to lindane for 1 h or 24 h compared with cultures exposed for 10 min, although the magnitude of the difference was modest (p ≤ 0.05). There were no significant differences in dye transfer between cultures exposed to lindane for 1 h or 24 h. These results show that an exposure as brief as 10 min to 100 μM lindane was sufficient to inhibit Lucifer yellow dye transfer 24 h later.

Bottom Line: Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus.To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20) rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane.After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure.

View Article: PubMed Central - HTML - PubMed

Affiliation: Toxicology Program, Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA. rlc@umich.edu

ABSTRACT

Background: Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus. Lindane, a pesticide used in the human and veterinary treatment of scabies and lice as well as in agricultural applications, inhibits uterine contractions in vitro, inhibits myometrial gap junctions, and has been associated with prolonged gestation length in rats. The aim of the present study was to investigate whether brief exposures to lindane would elicit sustained inhibition of rat uterine contractile activity and myometrial gap junction intercellular communication.

Methods: To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20) rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane. Lucifer yellow dye transfer between myometrial cells in culture was used to monitor gap junction intercellular communication.

Results: During a 1-h exposure, 10 micro M and 100 micro M lindane decreased peak force and frequency of uterine contraction but 1 micro M lindane did not. After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure. In cultured myometrial myocytes, significant sustained inhibition of Lucifer yellow dye transfer was observed 24 h after lindane exposures as brief as 10 min and as low as 0.1 micro M lindane.

Conclusion: Brief in vitro exposures to lindane have long-term effects on myometrial functions that are necessary for parturition, inhibiting spontaneous phasic contractions in late gestation rat uterus and gap junction intercellular communication in myometrial cell cultures.

Show MeSH
Related in: MedlinePlus