When you say you have loaded Camera Raw and DNG Reader 8.3, do you mean that you actually "installed" them? Actually, it isn't a DNG reader but a converter that is used to create DNG copies of raw files. It will be necessary for you to use it to convert your raw files in order for Lightroom 4 to be able to open them. The DNG converter does not automatically make it possible for earlier versions to read files from new cameras. The DNG converter is a standalone program that you will have to use outside of Lightroom to create your DNG files. Then you can import those files into Lightroom.
Installing ACR 8.3 RC will make Bridge and CS6 read the D610 files; however, it does nothing for LR 4.4.
LR 5.x is compatible with ACR 8.x, so my suggestion would be to install the LR 5.3 RC and see if you like it, and if so, then buy LR 5 and not worry about the DNGs.