Fig. 4.

Oxytocin promotes neurite outgrowth, but not branch point formation, in maturing primary rat neurons in vitro. Neurite length per area (a) and the number of branch points per area (b) were evaluated using live-cell imaging. Every 3 h, an analysis was performed. Subsequently, averages were taken per 12 h, which were normalized against the 0 h time point values of the PBS control group (n = 9). In the presence of 2μM oxytocin (n = 9), neurite length was increased from 24 h (p = 0.025) up to 48 h (p = 0.041), after which the beneficial effect gradually diminished. Both incubation time and oxytocin concentration had a significant effect on neurite length. Oxytocin concentrations of 0.5μM (n = 9) and 1μM (n = 9) did not significantly affect neurite length, and neither of the concentrations did increase branch point formation in comparison to the PBS control group. Differentiated HT22 cells do not show increased neurite length when treated with oxytocin regardless of presence or absence of Aβ₄₂. Black arrows indicate initial addition of oxytocin to medium as well as boost after 48 h (a, b). Representative images for primary neurons after 48 h of treatment with 2μM of OXT (left) and PBS (right) (c). One-way ANOVA and Tukey post-hoc analysis. Data points represent mean±SEM. *p < 0.05.