Effect of Degeneration of Nigro-Striatal Pathway on Calretinin Immunoreactivity in Genetic Absence Epilepsy and Non-Epileptic Rats


Kirazlı Ö., Çulpan Y., Turgan Aşık Z. N. , Gülçebi İdriz Oğlu M., Şehirli Ü. S. , Gülhan R., ...More

34. International Epilepsy Conference, 28 August - 01 September 2021

  • Publication Type: Conference Paper / Summary Text

Abstract

Purpose: Calcium binding proteins have essential roles on neurogenesis and neuronal functions. One of the calcium binding proteins, calretinin (CR), is expressed in aspiny and GABAergic interneurons and forms synaptic connections between dopaminergic and glutamatergic cortico-striatal inputs. The number of striatal CR positive neurons has been shown to change following the degeneration of neurons in nigro-striatal dopaminergic pathway. Moreover there are clinical and experimental results showing the sensitivity of CR expressing interneurons to epilepsy. This study focused on the effect of nigrostriatal dopaminergic neuronal loss on calretinin positive neurons during the epileptogenesis in genetic rat model of absence epilepsy.

Method: Stereotaxic surgery was used for injection of 6-hydroxydopamine (6-OHDA, 4mg/μl) to the medial forebrain bundle (AP:-1.4,ML:1,6 V:7,1 mm) of 30-day old Wistar (n=5) or genetic absence epilepsy rats from Strasbourg (GAERS) (n=5) in order to degenerate nigrostriatal dopaminergic pathway whereas naive rats were used as control groups. The rat brain sections (40 μm) were immunohistochemically stained for CR. The number of the CR positive neurons in the striatum and substantia nigra (SN) were counted on the fluorescence staining sections. GraphPad Prism V6 was used for the analysis of the results.

Result: There was no difference in the number of calretinin positive neurons in striatum between 6-OHDA injected groups and their control groups. The number of calretinin positive neurons significantly decreased in SN pars compacta (p<0.05) and SN pars reticulata (p<0.05) in 6-OHDA-injected Wistar rats and GAERS compared to their control groups.

Conclusions: Our results show that CR may have a protective role for the dopaminergic neurons against to degeneration of the nigro-striatal pathway. This study supported by the Scientific and Technological Research Council of Turkey, Project number:TUBITAK-SBAG-218S653