# Pinprick Hyperalgesia - What stimulus?

**URL:** <https://forum.painresearcher.net/t/pinprick-hyperalgesia-what-stimulus/349>\
**Category:** Animal Behavior and Models\
**Created:** [December 1, 2017, 10:44pm UTC](https://forum.painresearcher.net/t/pinprick-hyperalgesia-what-stimulus/349 "2017-12-01T22:44:19Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![achamess](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.painresearcher.net/achamess/32/534_2.png) [@achamess](https://forum.painresearcher.net/u/achamess)\
**Post date:** [December 1, 2017, 10:44pm UTC](https://forum.painresearcher.net/t/pinprick-hyperalgesia-what-stimulus/349/1 "2017-12-01T22:44:19Z")

</div>

What stimulus do you use for pin prick test in mice? I’ve seen various sharp “pins” described. Right now I use a 29 gauge insulin needle. That may be too sharp though. Also, the rate of force application matters and that’s hard to control.

What do you do? I feel like this is something we should standardize across labs.

@tberta @ShanTan @TSheahan @SamineniV @thicunha @fmoehring @areynolds

---

<div class="post-metadata">

**Author:** ![achamess](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.painresearcher.net/achamess/32/534_2.png) [@achamess](https://forum.painresearcher.net/u/achamess)\
**Post date:** [December 2, 2017, 3:00am UTC](https://forum.painresearcher.net/t/pinprick-hyperalgesia-what-stimulus/349/2 "2017-12-02T03:00:15Z")

</div>

Another clever insight from Arcourt et al. (2017).

> <https://www.ncbi.nlm.nih.gov/pubmed/27989460>
>
> Painful mechanical stimuli activate multiple peripheral sensory afferent subtypes simultaneously, including nociceptors and low-threshold mechanoreceptors (LTMRs). Using an optogenetic approach, we demonstrate that LTMRs do not solely serve as touch receptors but also play an important role in acute pain signaling. We show that selective activation of neuropeptide Y receptor-2-expressing (Npy2r) myelinated A-fiber nociceptors evokes abnormally exacerbated pain, which is alleviated by concurrent activation of LTMRs in a frequency-dependent manner. We further show that spatial summation of single action potentials from multiple NPY2R-positive afferents is sufficient to trigger nocifensive paw withdrawal, but additional simultaneous sensory input from LTMRs is required for normal well-coordinated execution of this reflex. Thus, our results show that combinatorial coding of noxious and tactile sensory input is required for normal acute mechanical pain signaling. Additionally, we established a causal link between precisely defined neural activity in functionally identified sensory neuron subpopulations and nocifensive behavior and pain.

To control the force of the pinprick, they attached a dissecting pin (unspecified model) to a 1g VF fiber. That way you can control the force. It doesn’t control the rate of force, but at least it makes the final force consistent.

Here is a screenshot of the video:

![01 PM](https://canada1.discourse-cdn.com/flex030/uploads/painresearcher/original/1X/0d957c35d265bde9188cd9958a7d2b24eb478072.png)

If you’re inside your university network, here is the video:

[https://ars.els-cdn.com/content/image/1-s2.0-S0896627316308650-mmc2.mp4](https://ars.els-cdn.com/content/image/1-s2.0-S0896627316308650-mmc2.mp4)

Also, later on in the paper, they rig up the pin-apparatus to a strain gauge so that they can monitor the exact timing of force application and withdrawal by the mouse. I’d like to know more about how they made that.

![09 PM](https://canada1.discourse-cdn.com/flex030/uploads/painresearcher/original/1X/eabdaf164f2eb71e07db95926fd1bc50bbff5c8d.jpg)