Effect of Subdural KCL Application on Trigeminal Nucleus Firing Pattern: A Single Unit Recording Study

Spreading depression (SD) in the brain, plays an important role in some disorders including migraine aura, cerebrovascular diseases, head injuryand transient global amnesia. Potassium has a role for SD in various animal models. It is common to apply high concentrations of KCl injection for triggering SD. Dural stimulation produces headache-like pain in humans and a well-known pain pathway exists from the dura to the brain via trigeminal nerve and its ganglion. The aim of this study is to investigating changes in the trigeminal nucleus activity pattern due to the use of KCl solution in subdural space in rat. Materials and Methods :Experiments were performed on 18 adult male rats. For recording EEG, 3 screws on skull, using elab , Science Beam instruments. apparatus were used. The electroencephalogram was filtered between 1 and100 Hz and was continuously monitored via an analog monitor scope. Application of KCL 0.2 ml via subdural injection at 15 minutes of session performed for each rat via a foramen in skull in fronto-parital area and firing rate was recorded for subsequent period of up to 45 minutes.To record single unit activity of trigeminal nucleus a tungsten electrode inserted as stereotaxic coordination (DV= 8.4, AP= -8.88, L= 2.2) in same side. Results: The recorded traces showed that when we apply KCL in all cells under recording the frequency and amplitudes wereincreased significantly. Some change in pattern of firing was seen as ramp increase in amplitudes or frequency and also some burst firing before permanent increase in frequency were seen. Conclusion: Changes in the fairing pattern and frequency of trigeminal nucleus could be a target for therapeutic or research purpose and need to further consideration.