There's mixed opinions on it, but I would say no. Pressure Treated lumber used to contain quite a lot of CCA, which contains arsenic. While they've changed the chemicals used in pressure treatment, its safety to small animals that chew is still of a questionable integrity.
the only wood my bunnies get is cuttings from our apple tree. Any pressure treated wood is treated with chemical to suppress mold and mildew and insects, so, generally it is poisonous.