PVALB and bipolar disorder: For instance, some studies showed that the postmortem samples collected from patients with schizophrenia, bipolar disorder, and major depression were characterized by low levels of parvalbumin or GAD67 gene expression [134,135], whereas some studies showed that these neurological disorders were also associated with the downregulation of somatostatin- and parvalbumin-expressing (but not calbindin-expressing) GABAergic cells in different brain regions of patients’ postmortem samples [136], reviewed for somatostatin in [137].