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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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Time- and concentration- related effects of treatment on percent uterine strips contracting during exposure (1 h). Uterine strips were exposed to lindane as described in Figure 1. Data are expressed as the percentage of strips retaining phasic contractions at the end of a 1-h exposure to lindane or DMSO (solvent control).
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Figure 3: Time- and concentration- related effects of treatment on percent uterine strips contracting during exposure (1 h). Uterine strips were exposed to lindane as described in Figure 1. Data are expressed as the percentage of strips retaining phasic contractions at the end of a 1-h exposure to lindane or DMSO (solvent control).

Mentions: The percentage of uterine strips still contracting following exposure to 10 μM lindane was reduced in a time-dependent manner, with only 1 of 7 treated uterine strips (14%) still contracting at the end of the 1-hr exposure period. Exposure to 100 μM lindane induced an even more pronounced reduction in uterine contractions with only 1 of 7 treated strips (14%) exhibiting phasic contractions after 20 min and cessation of all uterine contractions after 30 min (Fig. 3). These contractility results show that lindane-induced inhibition of spontaneous phasic uterine contractions increased with increased duration of exposure.


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

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

Time- and concentration- related effects of treatment on percent uterine strips contracting during exposure (1 h). Uterine strips were exposed to lindane as described in Figure 1. Data are expressed as the percentage of strips retaining phasic contractions at the end of a 1-h exposure to lindane or DMSO (solvent control).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Time- and concentration- related effects of treatment on percent uterine strips contracting during exposure (1 h). Uterine strips were exposed to lindane as described in Figure 1. Data are expressed as the percentage of strips retaining phasic contractions at the end of a 1-h exposure to lindane or DMSO (solvent control).
Mentions: The percentage of uterine strips still contracting following exposure to 10 μM lindane was reduced in a time-dependent manner, with only 1 of 7 treated uterine strips (14%) still contracting at the end of the 1-hr exposure period. Exposure to 100 μM lindane induced an even more pronounced reduction in uterine contractions with only 1 of 7 treated strips (14%) exhibiting phasic contractions after 20 min and cessation of all uterine contractions after 30 min (Fig. 3). These contractility results show that lindane-induced inhibition of spontaneous phasic uterine contractions increased with increased duration of exposure.

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