Intrinsic connections within the pedunculopontine tegmental nucleus are critical to the elaboration of post-ictal antinociception.
This study investigated the intrinsic connections of a key-structure of the endogenous pain inhibitory system, the pedunculopontine tegmental nucleus (PPTN), in post-ictal antinociceptive process through synaptic inactivation of the PPTN with cobalt chloride. Male Wistar rats (n = 6 or 7 per group), weighing 250-280 g, had the tail-flick baseline recorded and were submitted to a stereotaxic surgery for the introduction of a guide-cannula aiming at the PPTN. After 5 days of postoperative recovery, cobalt chloride (1 mM/0.2 µL) or physiological saline (0.2 µL) were microinjected into the PPTN and after 5 min, the tail-withdrawal latency was measured again at 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 min after seizures evoked by intraperitoneal injection of pentylenetetrazole (64 mg/kg). The synaptic inactivation of PPTN decreased the post-ictal antinociceptive phenomenon, suggesting the involvement of PPTN intrinsic connections in the modulation of pain, during tonic-clonic seizures. These results showed that the PPTN may be crucially involved in the neural network that organizes the post-ictal analgesia.
Departament of Pharmacology, Laboratory of Neuroanatomy and Neuropsychobiology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. dos Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.
Elaine Cristina
EC
Mazzei-Silva
Rithiele Cristina
RC
de Oliveira
Tayllon
T
dos Anjos Garcia
Luiz Luciano
LL
Falconi-Sobrinho
Rafael Carvalho
RC
Almada
Norberto Cysne
NC
Coimbra
D000818:Animals; D002408:Catheters, Indwelling; D002491:Central Nervous System Agents / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D008297:Male; D059225:Nociception / Q000187:drug effects / Q000502:physiology*; D010147:Pain Measurement; D058748:Pain Perception / Q000187:drug effects / Q000502:physiology*; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D045042:Pedunculopontine Tegmental Nucleus / Q000187:drug effects / Q000503:physiopathology*; D010433:Pentylenetetrazole; D017208:Rats, Wistar; D012154:Reticular Formation / Q000187:drug effects / Q000503:physiopathology; D012640:Seizures / Q000503:physiopathology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013623:Tail / Q000503:physiopathology; D013997:Time Factors
D002491:Central Nervous System Agents; D003035:Cobalt; C018021:cobaltous chloride; D010433:Pentylenetetrazole
pedunculopontine tegmental nucleus; post-ictal antinociception; synaptic transitory blockade; tonic-clonic seizures