title: Developmental stage-dependent impact of midazolam on calbindin, calretinin and parvalbumin expression in the immature rat medial prefrontal cortex during the brain growth spurt.
abstract: BACKGROUND
  Human epidemiological data suggest a link between anesthesia exposure in early postnatal life and subsequent lasting neurocognitive alterations. Understanding the underlying mechanisms of this potential association is of paramount importance in an attempt to develop protective strategies. While general anesthetics are powerful modulators of GABAergic neurotransmission, little is known about the impact of these drugs on developing GABAergic networks. Here we addressed this issue by evaluating the impact of a 6-h-long midazolam exposure on the development of calbindin-, calretinin- and parvalbumin-expressing GABAergic interneurons.
  
  
  METHODS
  Physiological expression patterns of calbindin-, calretinin-, and parvalbumin-positive neurons as well as the impact of a 6-h-long midazolam exposure on these cell populations were evaluated in the medial prefrontal cortex of Wistar rats at defined stages of the brain growth spurt using stereological analysis. Activated caspase-3 immunohistochemistry was used to quantify apoptotic death in controls and midazolam-treated subjects.
  
  
  RESULTS
  In control animals, the number of parvalbumin expressing cells significantly (p<0.01) increased while those of calbindin positive populations significantly (p<0.01) decreased between postnatal day 10 and 20. Expression of calretinin remained constant during this period. Immediately following exposure, midazolam induced neuroapoptosis at both early (postnatal day 5, p=0.016) and later (postnatal day 15, p=0.025) stages of brain development. While this did not diminish overall neuronal density in the medial prefrontal cortex, exposure at P5 led to a subsequent increase in the number of parvalbumin positive neurons in lower cortical layers, and midazolam administration at P15 increased the number of both parvalbumin and calretinin expressing neurons 5 days following exposure.
  
  
  CONCLUSIONS
  These observations demonstrate that midazolam exposure can impair the physiological differentiation patterns of GABAergic interneurons during the brain growth spurt. Considering the important role of GABAergic networks in neuronal physiology, these data provide us with one potential mechanism that could account for the lasting neurobehavioral and cognitive deficits observed in the context of anesthesia exposure in the early postnatal period.
authors.affiliation: Department of Anesthesiology, Pharmacology and Intensive Care, University Hospital of Geneva, Switzerland; Department of Fundamental Neurosciences, University of Geneva Medical School, Geneva, Switzerland.
authors.forename: Samira F
authors.initials: SF
authors.lastname: Osterop
authors.affiliation: Department of Fundamental Neurosciences, University of Geneva Medical School, Geneva, Switzerland.
authors.forename: Mari A
authors.initials: MA
authors.lastname: Virtanen
authors.affiliation: Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
authors.forename: Johanna R
authors.initials: JR
authors.lastname: Loepke
authors.affiliation: Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
authors.forename: Bernadin
authors.initials: B
authors.lastname: Joseph
authors.affiliation: Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Departments of Anesthesia and Pediatrics and Program in Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Loepke
authors.affiliation: Department of Anesthesiology, Pharmacology and Intensive Care, University Hospital of Geneva, Switzerland; Department of Fundamental Neurosciences, University of Geneva Medical School, Geneva, Switzerland; Geneva Neuroscience Center, University of Geneva, Geneva, Switzerland. Electronic address: laszlo.vutskits@unige.ch.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Vutskits
mesh_terms: D000375:Aging / Q000187:drug effects / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D064032:Calbindin 2 / Q000378:metabolism*; D064026:Calbindins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D059330:GABAergic Neurons / Q000187:drug effects / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D008874:Midazolam / Q000008:administration & dosage*; D010320:Parvalbumins / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D064032:Calbindin 2; D064026:Calbindins; D006993:Hypnotics and Sedatives; D010320:Parvalbumins; D008874:Midazolam
keywords: Anesthesia; Brain; Development; GABA; Plasticity