I have searched in NCBI-Gene database for this gene. However, the results showed only for Homo sapiens (Human) and Mus muscularis (mouse). Can i conclude that this gene is not present in the genome of rat.
It looks like there is no such gene in rat. You can check "homologene" on the NCBI website. You can also BLAST the mouse and/or human gene against the rat genome to check if there is a non-described homolog gene in rat.
Really thanks for your idea. I made BLAST the human MIAT gene with rat genome and identified that there is a similar sequence called LOC102552664. I emailed about this to RGD (Rat genome database) and got reply that they have changed the name of LOC102552664 to Miat.