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Traumatic brain injury (TBI) survivors often suffer from a post-traumatic syndrome with deficits in learning and memory. Calcium (Ca(2+)) has been implicated in the pathophysiology of TBI-induced neuronal death. However, the role of long-term changes in neuronal Ca(2+) function in surviving neurons and the potential impact on TBI-induced cognitive impairments are less understood. Here we evaluated neuronal death and basal free intracellular Ca(2+) ([Ca(2+)](i)) in acutely isolated rat CA3 hippocampal neurons using the Ca(2+) indicator, Fura-2, at seven and thirty days after moderate central fluid percussion injury. In moderate TBI, cognitive deficits as evaluated by the Morris Water Maze (MWM), occur after injury but resolve after several weeks. Using MWM paradigm we compared alterations in [Ca(2+)](i) and cognitive deficits. Moderate TBI did not cause significant hippocampal neuronal death. However, basal [Ca(2+)](i) was significantly elevated when measured seven days post-TBI. At the same time, these animals exhibited significant cognitive impairment (F(2,25)=3.43, p<0.05). When measured 30 days post-TBI, both basal [Ca(2+)](i) and cognitive functions had returned to normal. Pretreatment with MK-801 blocked this elevation in [Ca(2+)](i) and also prevented MWM deficits. These studies provide evidence for a link between elevated [Ca(2+)](i) and altered cognition. Since no significant neuronal death was observed, the alterations in Ca(2+) homeostasis in the traumatized, but surviving neurons may play a role in the pathophysiology of cognitive deficits that manifest in the acute setting after TBI and represent a novel target for therapeutic intervention following TBI.

Objective: Traumatic brain injury can cause a variety of impairments, including persistent alterations in personality, mood, and cognition. Antipsychotic agents are frequently used to treat pathologic behaviors in traumatic brain injury patients, but the influence of prolonged administration of such drugs on cognition after injury is unknown. The effects of two antipsychotic drugs on cognitive recovery after traumatic brain injury were assessed using the fluid percussion model in rats., Design: The typical antipsychotic, haloperidol, and the third-generation antipsychotic, olanzapine, were administered via intraperitoneal injection beginning 24 hr after injury and continuing daily for the duration of the study. Morris water maze performance was assessed on days 11-15 postinjury., Results: Haloperidol, an antagonist acting on D2-like dopamine receptors, exacerbated the cognitive deficits induced by injury, as injured rats treated with 0.30 mg/kg haloperidol performed worse in the Morris water maze than injured rats treated with vehicle., Conclusions: Our results demonstrate the importance of the D2 receptor in cognitive recovery after traumatic brain injury. Also, the data illustrate that some classes of antipsychotic drugs may influence cognitive recovery, and further research is needed to determine the optimal pharmacologic treatment of aggression, agitation, and other pathologic behaviors in patients with traumatic brain injury.

Moderately head injured patients often suffer long term neurological sequelae. There is no therapy for brain trauma and current treatments aim only to minimize secondary damage. These secondary effects are often triggered by the inability to re-establish ionic homeostasis after injury, due to large energy demands. Recent reports have demonstrated that neurons are capable of utilizing lactate as an energy source, thus this report examines the usefulness of lactate administration in the attenuation of behavioural deficits following a moderate brain injury. Lactate infusion (i.v.) was started 30 min after lateral fluid percussion injury and continued for 3 h. Cognitive deficits were determined using the Morris water maze. Lactate infused injured animals demonstrated significantly less cognitive deficits than saline infused injured animals. Thus, lactate infusion attenuated the cognitive deficits normally observed in this model, and therefore may provide moderately head injured patients with a treatment to help ameliorate the sequelae.