Hyperanxiety produced by periaqueductal gray injection of chondroitin sulphate glycosaminoglycan

We examined the effects of chondroitin sulphate C (CSC) on fear and anxiety parameters following injection of the glycosaminoglycan into the dorsal periaqueductal gray. Rats with chronically implanted cannulae were administered CSC (0.4 or 4.0 nmol) or vehicle (saline, 0.2 μl) and exposed to the elevated plus-maze test of emotionality. Intra-periaqueductal gray injection of CSC produced a dose-dependent anxiogenic effect as indicated by reduced entries into and time spent on the open arms, fewer excursions into the end of the open arms and by increased stretched attend posture, flat back approach and closed arm peeping-out behaviour. The behavioural effects of CSC appeared to be anxioselective, since the glycosaminoglycan did not influence measures of general (exploratory) activity, such as number of entries into the enclosed arms and amount of scanning, rearing and grooming. The present results show that CSC can produce an anxiogenic-like profile after injection into the dorsal periaqueductal gray. This is the first such report implicating an endogenous matrix glycosaminoglycan in neural mechanisms governing fear and anxiety.