Figure 8.

Anti-P and anti-NSPA antibodies induce calcium influx in cortical primary neurons. Graphs illustrate cells displaying different degrees of responsiveness. (A) α-hP₁₁ antibodies induce a sustained increase in calcium levels. The cells were incubated with 0.1 μg/ml (gray bar) and 0.2 μg/ml (black bar) of α-hP₁₁ antibodies. (B) Neuronal responses to α-hP₁₁ are specific and reversible. The increased calcium levels elicited by α-hP₁₁ returned to basal levels after washing the antibody (white bar) and were abrogated by preincubating the antibodies with the P peptide (black bar). (C) Dose-dependent responses to α-hP₁₁. The same cell showed increased responses to increasing amounts of antibody added after a wash out. Horizontal bars represent incubation time periods. (D) Chelation of extracellular Ca^{2 +} with 10 mM EGTA abolished the effects of α-hP₁₁. (E) 1 μg/ml of α-NSPA antibodies also provoke an increase in neuronal calcium levels of lower magnitude, which is reversible, specifically inhibited by the corresponding immunogenic peptide, and abolished by EGTA. (F) Neurons predominantly responded to both α-hP₁₁ and α-NSPA. Although 67 and 51% of neurons increased their calcium levels in response to either α-hP₁₁ or α-NSPA, respectively, only 5 and 3% of the astrocytes showed detectable responses. Control experiments showed that astrocytes responded to glutamate (not depicted). Error bars represent the mean ± SEM.