Related Experiment Video
Updated: Jun 13, 2026
07:55
Characterizing Mammalian Zinc Transporters Using an In Vitro Zinc Transport Assay
Published on: June 2, 2023
The zinc contraceptive effect: targets, timing, and quantitative thresholds.
Kirsten Shankie-Williams1, Margot Day1, Samson Dowland1
1School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia.
Biology Open
|June 12, 2026
Summary
Novel non-hormonal contraceptives are needed. Zinc intrauterine devices (IUDs) prevent pregnancy by inhibiting early embryo development, not by targeting sperm or the uterus.
Area of Science:
- Reproductive Biology
- Contraception Research
- Developmental Biology
Background:
- A critical need exists for novel non-hormonal contraceptive methods.
- Zinc-based intrauterine devices (IUDs) show promise, demonstrating 100% efficacy in rat models, but their mechanism of action is not fully understood.
Purpose of the Study:
- To investigate the contraceptive mechanism of zinc-based IUDs.
- To determine if zinc primarily affects sperm, embryos, or the uterine lining (endometrium).
Main Methods:
- Rats were fitted with zinc, copper, or nylon IUDs and mated.
- Embryo development and blastocyst formation were assessed in vivo and in vitro.
- Embryo attachment to human endometrial cells was evaluated.
Main Results:
- Fertilization occurred in all retrieved embryos, ruling out a primary spermicidal effect.
- Zinc significantly inhibited mouse embryo development in vitro, with dose-dependent effects on blastocyst formation.
- Zinc-treated embryos showed reduced attachment to endometrial cells, while zinc did not affect endometrial cell attachment of untreated embryos.
Conclusions:
- The primary contraceptive mechanism of zinc-based IUDs is the potent inhibition of pre-implantation embryo development.
- Zinc acts directly on the embryo, preventing its development to the blastocyst stage and subsequent implantation.
Related Concept Videos
01:22Birth Control Methods
Vasectomy is a surgical form of male sterilization that involves severing and sealing the vasa deferentia, preventing sperm from mixing with semen during ejaculation. Because a vasectomy does not impact the testes' ability to produce testosterone, hormone levels, libido, and sexual function generally remain unchanged. While vasectomy is highly effective in preventing pregnancy, with a success rate near 99.85%, rare cases of recanalization (spontaneous reconnection) can occur. Although vasectomy...
01:21Intrauterine Drug Delivery Systems
Controlled-release systems for intravaginal and intrauterine drug delivery have been developed primarily for the administration of contraceptive steroid hormones. These delivery routes circumvent first-pass hepatic metabolism, thereby enhancing bioavailability and allowing for reduced systemic dosages compared to oral administration. Such approaches contribute to improved therapeutic efficacy and patient compliance, particularly in long-term contraceptive regimens.Intravaginal Drug Delivery...
01:15Drug Concentration Versus Time Correlation
The plasma drug concentration-time curve is a crucial tool in pharmacokinetics, representing the drug's concentration in plasma at different time intervals post-administration. This curve illustrates the drug's journey from absorption into the systemic circulation, distribution to body tissues, and eventual elimination through excretion or biotransformation.
Two pivotal parameters are the minimum effective concentration (MEC) and the minimum toxic concentration (MTC). The MEC is the lowest drug...
Two pivotal parameters are the minimum effective concentration (MEC) and the minimum toxic concentration (MTC). The MEC is the lowest drug...
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
01:15Pharmacodynamic Models: Linear Concentration–Effect Model
The linear concentration–effect model, underpinned by the principle that pharmacological effect (E) is directly proportional to plasma drug concentration (C), emerges as a pivotal simplification of the Emax model for conditions where C is significantly less than EC50. This model portrays a linear trajectory of the concentration–effect relationship when drug levels are markedly below the EC50 threshold.Despite its inherent assumption of continuous effect augmentation with increasing drug...
01:14Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship
For drugs producing a quantal response, onset occurs when plasma concentration reaches a minimum effective level (Cmin). The drug's action duration depends on how long the plasma concentration remains above Cmin.Two primary factors influence this duration: dose size and the rate of drug removal from the action site. Both depend on the drug's redistribution to poorly perfused tissues and elimination processes. A larger dose promotes rapid onset and prolongs the effect's duration.Consider a...