Plasticity of the peptidergic mediation of spinal reflex facilitation after peripheral nerve section in the rat.
Wiesenfeld-Hallin. Z Z; Xu. X J XJ; Håkanson. R R; Feng. D M DM; Folkers. K K
Key Findings
- Both the tachykinin blocker Spantide II and the VIP blocker GRF‑1‑29 stop the reflex when the corresponding peptide is applied directly to the spinal cord.
- Spantide II reduces reflex enhancement caused by skin nerve activation in normal rats, but its effect weakens after the nerve is cut.
- GRF‑1‑29 does not affect reflex enhancement in normal rats, but it blocks it after the nerve has been cut, indicating a shift to VIP signaling after injury.
Practical Outcomes
- For biohackers, this research does not provide a clear, actionable protocol for humans. It mainly reveals a basic neurobiological switch after nerve damage, which may be interesting for understanding pain pathways but has no direct dosage or supplement guidance.
Summary
In rats, a peptide called GRF‑1‑29 (used as a VIP blocker) can stop a certain spinal reflex that normally gets stronger after nerve injury. The study shows that after cutting a nerve, the body switches from using one type of signaling molecule (tachykinins) to another (VIP) to boost that reflex.
Abstract
The effects of the tachykinin antagonist Spantide II (D-Nic-Lys1,3-Pal3,D-Cl2Phe5,Asn6,D-Trp7,9,Nl e11)-substance P (SP) and the vasoactive intestinal peptide (VIP) antagonist (Ac-Tyr1,D-Phe2)-GRF(1-29)-NH2 on the excitability of the spinal nociceptive flexor reflex to intrathecally (i.t.) applied SP and VIP, respectively, as well as the facilitation evoked by activation of cutaneous C-afferent was examined. Both antagonists blocked the effects of the respective neuropeptides in rats with both intact and sectioned sciatic nerves. Spantide II antagonised C-afferent induced reflex facilitation in rats with intact nerves, but the degree of antagonism declined after axotomy. In contrast, the VIP antagonist did not block C-afferent induced facilitation in rats with intact nerves, but did so after axotomy. The results indicate that the role of tachykinins in mediating C-afferent-induced reflex facilitation is taken over by VIP after axotomy.
Study Information
pubmed
1990
1990-08-24T00:00:00.000Z
10.1016/0304-3940(90)90089-r