Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

The overall goal of this procedure is to measure the intrauterine pressure of a pregnant mouse in vivo. This is accomplished by first locating the uterine horn containing the highest number of viable pups. The day of surgery will depend on your model and may require troubleshooting.

The catheter of a small TER is then threaded into the horn and the TER is activated. Ultimately, the intrauterine placement of the TER allows assessment of the real time contractual pressure patterns of the pregnant animal. This method can help answer key questions in the reproductive field, such as which proteins and signaling molecules are responsible for the induction and contractile states of pregnancy.

Visual demonstration of this method is critical as there’s little room for catheter insertion deviation when threading the catheter into the pregnant uterus without leading to an increased risk of fetal demise. Before beginning the procedure, clean the surgery surface with 70%ethanol and turn on the heating pad and bead sterilizer. Next, shave the abdomen of an anesthetized mouse from the bladder to the bottom of the ribs and place the mouse on the heating pad.

The nozzle the mouse is placed under is for anesthetization, not respiration. The mouse is more quickly sedated, went on its abdomen than went on its back. Pull on a pair of sterile gloves.

Place the packaging under the mouse as your sterile surgical surface using sterile forceps. Next, place the telemeter on sterile gauze. Then gently squeeze the catheter of the TER syringe to draw gel into the tip of the catheter.

Load a pipette with two microliters of surgical glue and place the pipette on a sterile surface. Then swab the surgical area on the animal sequentially with iodine and 70%ethanol. Place a fenestrated drape over the mouse.

And then after confirming complete anesthetization by toe pinch, make a small vertical midline incision in the skin, followed by a similar incision through the underlying body wall muscle. Now gently pull the uterus out of the body cavity and locate the uterine horn containing the highest number of viable pups. Use three millimeter cutting edge spring scissors to make a small incision at the top of the uterine horn.

Then thread the catheter without squeezing between the uterine wall and the fetal sax. Inserting the catheter past several sacks to reduce its accidental removal. When the catheter is in place, dispense the surgical glue onto the site of insertion to adhere the catheter to the uterine horn.

And wait a few seconds for the glue to become rigid. Then carefully place the uterus back inside the body cavity and place the TER on the opposite side of the insertion site. Now use a six zero absorbable suture to make a purse stitch, followed by three to four individual stitches to close the body cavity, suture the skin by the same technique, but with a six zero non-absorbable suture.

Then swab a topical analgesic ointment over the incision site and inject 0.3 to 0.4 milliliters of sterile saline subcutaneously to help rehydrate the animal. Monitor the mouse after surgery until it is fully awake. Placing the animal back in its cage when it is able to freely hold its head above the table.

Monitor the daily post-surgery progress in a log and feed the mouse specialized recovery diet food as well. Examine the sutures to make sure they are not pulled out. Taken care not to handle the mouse excessively at least two to three days.

After the surgery, place a magnet near the animal to turn on the TER and place the mouse cage on the receiver. The light on the receiver will turn on if the TER is activated. Calibrate a brand new TER with a provided manufacturer specific calibrations, and then within the TER software right click on animal.

Then click start sampling continuous to allow sampling at rates of up to 500 hertz. Taking care that the software is set to save and trace in this experiment. A real-time in vivo intrauterine pressure sampling was paired with the simultaneous video recording of the mouse to capture the exact time of each pup’s delivery, allowing correlation of the delivery time to the intrauterine pressure of the mother.

Additionally, a moving average of the intrauterine pressure was also plotted to more easily visualize the sustained increases in intrauterine pressure characteristic of the contractions associated with the labor process. Intrauterine telemetry can also be used to test in vivo responses to pharmacological agents during pregnancy, for example, for early drug testing. Prior to clinical trials.

In this representative experiment, the TER was implanted at the same time as a micro osmotic pump delivering a steady rate of oxytocin. Note the differences observed in the recordings between nonpregnant and pregnant mice treated with continuous oxytocin. By injecting micro RNA expressing lentil viral vectors into the myometrium during the TER implantation, the uterine specific knockdown of a gene of interest can be examined.

For example, as seen in these representative tracings administration of scrambled or cure 7.1 micro RNA demonstrates that knocking down expression of the potassium channel cure 7.1 causes intrauterine pressure to increase While attempting the surgical procedure. It’s important to remember not to force or squeeze the catheter over the TER.