Hubungan ekspresi reseptor Dopamin D1 dengan tampilan memori kerja :: Kajian Neurohistokimiawi keterlibatan Neuron Dopaminergik Amygdala Basolateralis dan CA1 Hippocampus tikus (Rattus norvegicus) Pascastres kronik

HANDAYANI, Ety Sari, Prof.dr. Soedjono Aswin, Ph.D

2006 | Tesis | S2 Ilmu Kedokteran Dasar dan Biomedis

Latar Belakang. Stres kronik dapat menurunkan fungsi memori kerja melalui mekanisme hipodopaminergik. Diketahui bahwa sistem dopaminergik CA1 hippocampus, amygdala basolateralis dan cortex prefrontalis terlibat dalam pembentukan memori kerja. Pada keadaan hipodopaminergik dilaporkan adanya peningkatan ekspresi reseptor dopamin D1 di cortex prefrontalis sedangkan ekspresi reseptor dopamin D1 di amygdala basolateralis dan CA1 hippocampus selama stres kronik belum diketahui. Tujuan. Mengungkapkan :1) hubungan ekspresi reseptor dopamin D1 di amygdala basolateralis dengan kinerja memori kerja tikus, 2) hubungan ekspresi reseptor dopamin D1 CA1 hippocampus dengan kinerja memori kerja tikus, 3) hubungan ekspresi reseptor dopamin D1 amygdala basolateralis dengan ekspresi reseptor dopamin D1 CA1 hippocampus tikus setelah paparan stres listrik kronik. Metode. Subyek terdiri dari 10 ekor tikus, dibagi menjadi kelompok kontrol (K), dan kelompok perlakuan (P) (lima ekor setiap kelompok). Memori kerja diuji dengan maze radial 8 lengan selama 12 hari. Setelah latihan, dilakukan pengujian memori kerja. Mulai hari ke-13, satu kelompok tikus diberi perlakuan stres listrik berupa sengatan aliran listrik sebesar 60 V selama 10 detik dengan interval 10 detik selama 15 menit setiap harinya selama 25 hari. Selanjutnya, dilakukan pengukuran memori kerja pada kedua kelompok tikus selama 12 hari. Otak tikus difiksasi dengan perfusi transkardial dan dilakukan diseksi amygdala basolateralis dan CA1 hippocampus. Ekspresi reseptor dopamin D1 amygdala basolateralis dan CA1 hippocampus dideteksi dengan anti rat D1 receptor antibody pada potongan parafin amygdala basolateralis dan CA1 hippocampus. Hasil. Stres kronik menyebabkan penurunan tampilan memori kerja yang diikuti dengan peningkatan (up regulation) ekspresi reseptor dopamin D1 amygdala basolateralis dan CA1 hippocampus. Peningkatan ekspresi reseptor dopamin D1 amygdala basolateralis tidak berhubungan dengan peningkatan ekspresi reseptor dopamin D1 CA1 hippocampus. Kesimpulan. 1) stres kronik dapat menurunkan memori kerja dan 2) Neuron pascasinaptik pada sistem dopaminergik di amygdala basolateralis dan CA1 hippocampus merespon keadaan stres kronik dengan peningkatan ekspresi reseptor dopamin D1.

Background. . Chronic stress may decrease working memory due to hippo dopaminergic mechanism. Dopamine receptor in CA1 hippocampus, basolateral amygdala and prefrontal cortex involve in the development of working memory. It has been reported that the expression of dopamine receptor in prefrontal cortex increases during chronic stress. The expression of dopamine receptor in CA1 hippocampus and basolateral amygdala during chronic stress are unkown. Objective. The aim of this research was to investigate: 1) the relation between the expression of dopamine D1 receptor in basolateral amygdala and working memory, 2) the relation between the expression of dopamine D1 receptor in CA1 hippocampus and working memory and 3) the relation between the expression of dopamine D1 receptor in basolateral amygdala and CA1 hippocampus in rat after chronic electric stress. Methods. The rats were divided randomly into two groups (each group consisted of five rats). Working memory is assessed with eight radial arm maze. After trained, working memory was tested for 12 days. Starting at the 13rd day, one group was treated with electric stress (60 V, 10 s duration, 10 s interval, 15 minute/day) for 25 days. After that, the performance of working memory was tested for both groups for 12 days. Rat’s brain was fixed by transcardial perfusion and dissected out. The expression of dopamine D1 receptor were detected in paraffin section on basolateral amygdala and CA1 hippocampus with anti rat D1 receptor antibody. Result. Chronic stress-induced decrease of working memory performance is related to the up-regulation of dopamine D1 receptor in basolateral amygdala and CA1 hippocampus. The increases of dopamine D1 receptor expression in basolateral amygdala is not related with the increases of dopamine D1 receptor in CA1 hippocampus after chronic electric stress. Conclusion. 1) chronic stress may decrease working memory, and 2) the neuron of amygdala basolateral and CA1 hippocampus up-regulate the expression of dopamine D1 receptor as a response of chronic stress.

Kata Kunci : Chronic stress, working memory, dopaminergic system, dopamine D1 receptor, basolateral amygdala, CA1 hippocampal