Early 5-HT6 receptor blockade prevents symptom onset in a model of adolescent cannabis abuse (2020)
Figure 1

Figure 1. Administration of THC during adolescence to mice induces mTOR activation in the PFC and cognitive deficits in adulthood that depend on 5-HT6 receptors

A. Schema of the experimental paradigm used for drug administration. Mice were injected daily with THC (5 mg/kg) or vehicle (Veh) during adolescence, from PND 30 to 45. SB258585 (SB, 2.5 mg/kg) or rapamycin (Rapa, 1.5 mg/kg) were administered concomitantly with THC- or vehicle. Biochemical and behavioral experiments were performed from PND 60.

B. Top: representative Western blots assessing mTOR phosphorylation at S2448 and p70S6K phosphorylation at T389 as indexes of mTOR activity in PFC of adult WT mice are illustrated. Bottom: data represent the ratios of immunoreactive signals of the anti phospho-mTOR (S2448) or anti phospho-p70S6K (T389) antibodies to the immunoreactive signal of the anti-β-actin antibody and are expressed in % of values in vehicle-injected WT mice. They are the means ± S.E.M. of results obtained in five mice per group. * p < 0.05; ** p < 0.01, one-way ANOVA followed by Newman-Keuls test.

C. Top: schemas illustrating the behavioral tasks examined in WT mice. Bottom: the plots represent the discrimination index for the novel object recognition task (Vehicle N=11, THC: N=11, THC+SB: N=11, THC+Rapa: N=12), the sociability index (Vehicle: N=11, THC: N=11, THC+SB: N=11, THC+Rapa: N=12) and the discrimination index for the social discrimination task (N=8 for each group), measured in each condition. * p < 0.05, ** p < 0.01, one-way ANOVA followed by Bonferroni test (error bars correspond to the mean ± SEM, the dotted line to a discrimination index (exploration of novel object - exploration of familiar object/total object exploration) equal to zero.

D. Top: representative Western blots assessing mTOR phosphorylation at S2448 and p70S6K phosphorylation at T389 in PFC of adult 5-HT6-/- mice are illustrated. Bottom: data represent the ratios of immunoreactive signals of the anti phospho-mTOR (S2448) or anti phospho-p70S6K (T389) antibodies to the immunoreactive signal of the anti-β-actin antibody and are expressed in % of values in vehicle-injected 5-HT6-/- mice. They are the means ± S.E.M. of results obtained in four mice per group. n.s. p > 0.05, one-way ANOVA followed by Newman-Keuls test.

E. Top: schemas illustrating the behavioral tasks in 5-HT6-/- mice. Bottom: the plots represent the discrimination index for the novel object recognition test (discrimination index: 0.30 ± 0.05, N=10 and 0.31 ± 0.03, N=11, for THC+Vehicle and Vehicle+Vehicle conditions, respectively, p > 0.05), the 3-chamber social preference test (sociability index: 0.49 ± 0.04, N=10 and 0.48 ± 0.07, N=11 for THC+Vehicle and Vehicle+Vehicle conditions, respectively, p > 0.05) and the social discrimination test (discrimination index: 0.15 ± 0.06, N=8 and 0.21 ± 0.06, N=8 for THC+Vehicle and Vehicle+Vehicle conditions, respectively, p > 0.05), measured in each condition. One-way ANOVA followed by Bonferroni test (error bars correspond to the mean ± SEM, the dotted line corresponds to a discrimination index equal to zero).