The expression of G protein-coupled receptor kinase 5 and its interaction with dendritic marker microtubule-associated protein-2 after status epilepticus

Objective: Acute seizures induced dendritic formation and synaptogenesis promotes aberrant circuitry development and further aggravates underlying conditions towards chronic epilepsy. The G protein-coupled receptor kinase-5 (GRK5) served as a key modulator in neurogenesis and the establishment of functional neuronal circuitry. This included dendritic development, as its dysfunction could cause different central nervous system disorders, including Alzheimer's disease. However, the involvement of GRK5 in the progression of epilepsy remains unclear. The purpose of this study is to investigate the involvement of GRK5 in epilepsy, as well as its potential correlation with dendritic formation after status epilepticus.

Methods: 120 rats were divided into control and model groups. The rats in the model group were injected intraperitoneally with lithium chloride-pilocarpine hydrochloride to establish the rat model of status epilepticus (SE). The brain and hippocampus were collected at 1, 3, 7, 14 and 28days post SE induction. The expression and distribution of GRK5 and the dendritic marker microtubule-associated protein-2 (MAP-2) were detected in the hippocampus via western blot or immunohistochemistry. The co-localization of GRK5 with MAP-2 was examined via laser confocal double immunofluorescence staining. The interactions between GRK5 and MAP-2 during epileptogenesis were evaluated via immunoprecipitation.

Results: GRK5 was distributed in all areas of the hippocampus. Its expression was significantly up-regulated in the hippocampal CA1, DG, and H areas at 7d and 14d after SE. After 14d it began to reduce. and then reduced. MAP-2 primarily existed in the neuronal dendrites of the hippocampal subregion. Its expression was enhanced at 3d. It reached its maximum level at 14d after SE, where it then began to fall. The confocal microscope analysis revealed that GRK5 was co-located well within MAP-2 positive cells. The interaction between GRK5 and MAP-2 became enhanced at 7d and 14d after SE.

Conclusions: GRK5 was involved in the development of epilepsy. It was associated with dendritic formation in epilepsy. This study provides a new perspective for elucidating the epilepsy pathogenesis. The concrete mechanisms of the GRK5 within epileptogenesis require further research.