Dolor pulpar: modificaciones en la expresión de s100ß y serotonina en subnúcleos del trigémino

MARIELA CELESTE CANZOBRE; NICOLÁS SEBASTIÁN FOSSER; HUGO RÍOS

Mar del Plata, Pcia de Buenos Aires

Congreso; XXXVII Reunión Anual de la Sociedad Argentina de Investigación Odontológica, división de la International Association for Dental Research; 2005

The spinal trigeminal nucleus is one of the most important centres in the modulation of orofacial pain.  It is well known that astrocytes can control neuronal excitability and neuronal plasticity when a painful stimulus occurs. S100ß protein has been involved in this process.  This protein induces nitric oxide synthase, which in turn produces an increase in the levels of the neuromodulator nitric oxide, which participates in the beginning and modulation of craniofacial and dental pain.  In the same manner, S100ß protein has been implicated as a neurotrofic factor of serotoninergic neurons, and in the neural regulation of serotoninergic neurons.  On the other hand, serotonin (5HT) have been involved both in central and peripheral mechanisms of orofacial pain.             In this work we have studied the expression of the astrocytes protein S100ß and neuronal 5HT in the trigeminal spinal nucleus, in a model of neuroplasticity after injury and inflammation of peripheral tissues and nerves.  Adult Wistar rats were used and the first left inferior molar pulpar chamber was opened and the pulp exposed, which produces an inflammatory response.  In this situation, animals show a behaviour that can be equivalent to human pain.   Animals were anesthetized, perfused with paraformaldheyde, the brainstem was dissected and processed for immunocytochemistry for the analysis of astrocytes and neuronal modifications.  Glial and neuronal analyses were done at 2 hours, 7 and 35 days post pulpar injury.  Immunocytochemistry procedures were achieved using primary antibodies anti  astrocytes protein S100ß and anti 5HT.  Spinal nucleus modifications were analyzed at different levels of the nucleus from cervical 4 to medial protuberancial levels.             Our results show that there is an astroglial reaction based on an increase in S100ß positive astrocytes.  These modifications are evident in the caudal subnucleus.  On the other hand, serotoninergic fibers showe an increment in its extension and in the number of variocosities, showing significatives changes in the injured side of caudal subnucleus.  This work was supported by grants from UBA [[UBACyT O007] and CONICET [PEI6069].