title: The differential effects of prenatal and/or postnatal rapamycin on neurodevelopmental defects and cognition in a neuroglial mouse model of tuberous sclerosis complex.
abstract: Tuberous sclerosis complex (TSC) is caused by heterozygous mutations in either the TSC1 (hamartin) or the TSC2 (tuberin) gene. Among the multisystemic manifestations of TSC, the neurodevelopmental features cause the most morbidity and mortality, presenting a considerable clinical challenge. Hamartin and tuberin form a heterodimer that inhibits the mammalian target of rapamycin complex 1 (mTORC1) kinase, a major cellular regulator of protein translation, cell growth and proliferation. Hyperactivated mTORC1 signaling, an important feature of TSC, has prompted a number of preclinical and clinical studies with the mTORC1 inhibitor rapamycin. Equally exciting is the prospect of treating TSC in the perinatal period to block the progression of brain pathologies and allow normal brain development to proceed. We hypothesized that low-dose rapamycin given prenatally and/or postnatally in a well-established neuroglial (Tsc2-hGFAP) model of TSC would rescue brain developmental defects. We developed three treatment regimens with low-dose intraperitoneal rapamycin (0.1 mg/kg): prenatal, postnatal and pre/postnatal (combined). Combined rapamycin treatment resulted in almost complete histologic rescue, with a well-organized cortex and hippocampus almost identical to control animals. Other treatment regimens yielded less complete, but significant improvements in brain histology. To assess how treatment regimens affected cognitive function, we continued rapamycin treatment after weaning and performed behavioral testing. Surprisingly, the animals treated with the combined therapy did not perform as well as postnatally-treated animals in learning and memory tasks. These results have important translational implications in the optimization of the timing and dosage of rapamycin treatment in TSC affected children.
authors.affiliation: Program in Human and Molecular Genetics, University of Texas Health Science Center, Houston, TX, USA.
authors.forename: Sharon W
authors.initials: SW
authors.lastname: Way
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Rozas
authors.forename: Henry C
authors.initials: HC
authors.lastname: Wu
authors.forename: James
authors.initials: J
authors.lastname: McKenna
authors.forename: R Michelle
authors.initials: RM
authors.lastname: Reith
authors.forename: S Shahrukh
authors.initials: SS
authors.lastname: Hashmi
authors.forename: Pramod K
authors.initials: PK
authors.lastname: Dash
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gambello
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D003071:Cognition / Q000187:drug effects*; D004195:Disease Models, Animal; D006801:Humans; D007858:Learning / Q000187:drug effects; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D020123:Sirolimus / Q000008:administration & dosage*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D014402:Tuberous Sclerosis / Q000188:drug therapy* / Q000196:embryology / Q000523:psychology*; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; C000624653:TSC2 protein, human; C000624654:Tsc2 protein, mouse; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus