INS and nicotine dependence: Interestingly, by symptom onset at P60 in Mecp2e1-/+ females, 6 dysregulated KEGG pathways including nicotine addiction, long-term potentiation, insulin secretion, glutamatergic synapse, cAMP signaling, and amphetamine addiction (found in P30 Pvalb and Sst neurons) were distinctly significantly enriched in L5 and L6 excitatory neurons (Fig. 2f).