Fig. 5.

Adult mice chronically exposed to ∆9-THC during adolescents differ from vehicle controls in their extrasynaptic GluN1 distribution in varying sized dendrites within the PL-PFC (a–d) and interactions with a stranger mouse (SOC) vs. novel object (NOV) (e–g). In a and b, the bar graphs respectively show that adolescent ∆9-THC produces a significant decrease in extrasynaptic plasmalemmal GluN1 in small, medium and large dendrites, without effect on GluN1 cytoplasmic distribution in the PL-PFC dendrites of adult mice. In a and b, ANOVA *p < 0.05 and numbers = number of GluN1-labeled dendrites. Schematic drawings in c and d respectively summarize the GluN1-immunogold distribution in PL-PFC dendrites of adult mice receiving ∆9-THC or vehicle during adolescents. In each treatment group, transverse sections through small (c.1), medium (c.2), and large (c.3) dendrites are represented by oval shapes with a white line drawn around the perimeter to indicate the plasmalemma that encloses the cytoplasmic compartment. Each of these dendritic profiles is bisected by a double line to separate portions that are contacted by excitatory (+) and inhibitory (−) axon terminals (i.e., synaptic) or without axonal contact (i.e., non-synaptic (non-Syn)). CB1R labeling is shown by dark shading in a subgroup of the inhibitory-type terminals. Data from bar graphs in Fig. 3e, f are schematically shown by an increase (up arrow) in plasmalemmal density and the corresponding decrease (down white arrow) in the cytoplasmic density of GluN1-immunogold particles (small circles) exclusively in large dendrites of mice receiving ∆9-THC compared with vehicle. In contrast, data summarized from bar graphs in this figure show a decrease (down arrow) in GluN1-immunogold density on the extrasynaptic plasma membrane of all dendrites without synaptic contact (i.e., non-synaptic). Bar graphs in e and f respectively show that administration of ∆9-THC compared with vehicle during adolescence significantly increases the time spent in portions of the chamber in contact with a stranger mouse and decreases the entries into the contact zone surrounding a novel object. ANOVA shows a statistically significant treatment effect on (ambulatory time: (F(1,10) = 12.07, p = 0.006) and number of entries: (F(1,10) = 11.03, p = 0.008). g Representative tracking of adult mice that received vehicle or ∆9-THC during adolescence shows that ∆9-THC enhances the mobilization to portions of the two interconnected compartments within which dashed lines indicate the perimeter of the contact zone around the stranger mouse (SOC) and novel object (NOV)