I am guessing you meant:  "vibratome"....[having checked that there are a lot of articles in the web 'vivratome' misspelling the known word "vibratome"] or is it "cryotomy" in connotation with a "Vibratome UltraPro 5000 Cryostat" you perhaps are using??   Since sucrose-addition to the (buffer) medium after fixation per se / alone is only a functional "cryoprotectant" and -at this stage doesn't harm really structures you could try to reprocess (down to hydrous, buffered FA (PFA)-fixative [IMPORTANT QUÈSTIONS: was it really 10% PARA-formaldehyde or - as usually used: 4% BUFFERED PFA-solution or was it 10% Formalin instead? -  DID YOU USE PERFUSION- or IMMERSION-fixation?...the former optimal for your task! How old are your rats...there might be differences with their age when their brains are examined: esp. size, consistency, and therefore fixation "times=duration of", etc. ]  by incubating / immersing / postfixing your specimens in decreasing sugar concentrations  / in buffer) and to improve fixation by storing (and intermittently shaking, or better, permanently rotating your brain specs) again in fixative solution proper for a certain duration....which will depend on the age and size/volume of the brain you have to fix.......       and, last but not least:

If you - indeed- use a cryomicrotome (which can be termed as above) for your sections there are many other reasons why your brain sections are tearing / dragging /'dragged'.