Compression of the trigeminal ganglion produces prolonged nociceptive behavior in rats

Abstract

The present study is the first demonstration of prolonged nociceptive behavior in the trigeminal region following compression of the trigeminal ganglion in rats. Experiments were carried out on male Sprague-Dawley rats mounted onto a stereotaxic frame under pentobarbital sodium anesthesia. For compression of the trigeminal ganglion, a 4% agar solution (8microl) was injected into the trigeminal ganglion through a stainless steel injector (24 gauge), which extended 2mm beyond the end of a guide cannula (21 gauge). Following agar injection, the injector and guide cannula were removed. In the control group, rats were sham operated without agar injection. Air-puff thresholds (mechanical allodynia), pin prick responses (mechanical hyperalgesia), and spontaneous scratching behavior were examined 3 days before surgery and at 3, 7, 10, 14, 17, 21, 24, 30, and 40 days after surgery. Data were analyzed using a repeated measures ANOVA followed by multiple group comparisons using the LSD post-hoc test. Air-puff thresholds significantly decreased after compression of the trigeminal ganglion. Mechanical allodynia was established within 3 days and lasted beyond postoperative day 24. Mechanical hyperalgesia was also evident 3 days after compression and persisted until the 40th postoperative day. Although mechanical allodynia and hyperalgesia appeared bilaterally, the ipsilateral side was significantly more sensitive. Intraperitoneal treatment with carbamazepine significantly blocked mechanical allodynia produced by compression of the trigeminal ganglion. These findings suggest that prolonged nociceptive behavior following compression of the trigeminal ganglion may mimic trigeminal neuralgia in this animal model.

Progesterone Produces Antinociceptive and Neuroprotective Effects in Rats with Microinjected Lysophosphatidic Acid in the Trigeminal Nerve Root

“…Mechanical hyperalgesia was assayed using a pin-prick test following the same strict rule of habituation and testing environments for von Frey testing, as described previously [31,50]. Briefly, the rats were left to adapt to the observation cage for 30 min prior to the actual stimulation.…”

The Presence of Neuropathic Pain Predicts Postoperative Neuropathic Pain Following Trigeminal Nerve Repair

“…3,4 The exact cause of neuropathic pain of the trigeminal system is still unknown, but several risk factors have been suggested, including changes in ion channels, putative neurotransmitter excess or inhibition, endothelin receptor activity, and glial cell dysfunction causing trigeminal hyperexcitability following constriction and/or transection injuries of different branches of the trigeminal nerve. [5][6][7][8] However, an injury or insult to the nerve is the common clinically measureable etiology of the onset of neuropathic pain of the trigeminal nerve.…”

Participation of central GABAAreceptors in the trigeminal processing of mechanical allodynia in rats

“…Withdrawal responses produced by ten successive trials of ramped air-puff pressure (4 seconds in duration, 10 second intervals) were examined as described previously [16171819]. The intensity of the air-puff pressure was controlled using a pneumatic pump (BH2 system, Harvard Apparatus).…”