Propofol promotes blood-brain barrier breakdown and heat shock protein (HSP 72 kd) activation in the developing mouse brain.

Anesthetic agents induce cellular stress that may affect blood-brain barrier (BBB) permeability permeability in the developing brain causing brain dysfunction. In this investigation, effects of Propofol on cellualr stress using inducible heat shock protein (HSP72) and BBB breakdown employing albumin immunoreactivity in the mouse brain were examined. Propofol was administered to in mice on the postnatal day 10 once (10 mg/kg or 60 mg/kg subcutaneously). On the 75th day, HSP72 and albumin immunostaining were examined on 3-µm thick paraffin sections in the midbrain areas using standard protocol. Saline-treated and age-matched mice served as controls. Propofol dose-dependently produced a significant increase in the number of HSP72 and albumin-positive cells in cortex, hippocampus, thalamus and hypothalamus, a feature not seen in the saline-treated group. HSP72 and albumin activity in the propofol-treated group was largely confined to neurons and often localized to their cell cytoplasm and/or nucleus. HSP72 and albumin expression was the most prominent in cerebral cortex and in hippocampus, followed by hypothalamus and thalamus. These novel observations suggest that anesthetic agents, by inducing cellular stress in the developing brain may disrupt the BBB permeability that may have long lasting effects on adult brain function.

Neonatal exposure to propofol affects BDNF but not CaMKII, GAP-43, synaptophysin and tau in the neonatal brain and causes an altered behavioural response to diazepam in the adult mouse brain.

Animal studies have shown that neonatal anaesthesia is associated with acute signs of neurodegeneration and later behavioural changes in adult animals. The anaesthetic effect of propofol is thought to be mediated by γ-amino butyric acid (GABA)(A) receptors. The present study investigated the effects on proteins important for normal neonatal brain development (i.e. BDNF, CaMKII, GAP-43, synaptophysin and tau), and adult spontaneous motor and anxiety-like behaviours in response to diazepam, after neonatal exposure to propofol. Ten-day-old mice were exposed to 0, 10 or 60 mg/kg bodyweight propofol. Neonatal propofol exposure changed the levels of BDNF in the brain, 24h after exposure, but did not alter any of the other proteins. Neonatal propofol exposure significantly changed the adult response to the GABA-mimetic drug diazepam, manifest as no change in spontaneous motor activity and/or reduced sedative effect and an extinguished effect on the reduction of anxiety-like behaviours in an elevated plus maze. Although no adult spontaneous behavioural changes were detected after neonatal propofol exposure, the exposure caused an adult dose-dependent decrease in the response to the GABA-mimetic drug diazepam. These changes may be due to neonatal alterations in BDNF levels.

Neonatal ketamine exposure results in changes in biochemical substrates of neuronal growth and synaptogenesis, and alters adult behavior irreversibly.

Ketamine, an anaesthetic agent used in newborns and toddlers, has been shown to induce neurodegeneration and alter adult behavior in mice, when administered during the neonatal period. Mammals have a marked period of rapid brain growth and development (BGS), which is postnatal in mice and rats, spanning the first 3-4 weeks of life and reaching its peak around postnatal day 10. CaMKII and GAP-43 play important roles during the BGS in mammals. In the present study, 10 days old mice were exposed to 5-25 mg ketamine/kg bw and 24 h later brains were analyzed for calcium/calmodulin-dependent protein kinase II (CaMKII) and growth associated protein-43 (GAP-43) and at an age of 2 and 4 months the animals were tested for spontaneous behavior. The protein analysis showed that CaMKII increased significantly in hippocampus, but not in cortex, in animals 24h after exposure to ketamine. GAP-43 showed a significant increase in hippocampus, but a significant decrease in cortex for the highest ketamine dose. When looking at the adult behavior it was clear that neonatal ketamine exposure affected spontaneous behavior and habituation in a dose-response-related manner and that these behavioral disturbances were not transient but still persisted 2 months later. Taken together, this shows that ketamine affects important proteins involved in normal maturation of the brain and induce functional deficits in the adult individual, which further strengthen our findings concerning ketamine as a developmental neurotoxicological agent.

Neonatal exposure to a combination of N-methyl-D-aspartate and gamma-aminobutyric acid type A receptor anesthetic agents potentiates apoptotic neurodegeneration and persistent behavioral deficits.

BACKGROUND: During the brain growth spurt, the brain develops and modifies rapidly. In rodents this period is neonatal, spanning the first weeks of life, whereas in humans it begins during the third trimester and continues 2 yr. This study examined whether different anesthetic agents, alone and in combination, administered to neonate mice, can trigger apoptosis and whether behavioral deficits occur later in adulthood. METHODS: Ten-day-old mice were injected subcutaneously with ketamine (25 mg/kg), thiopental (5 mg/kg or 25 mg/kg), propofol (10 mg/kg or 60 mg/kg), a combination of ketamine (25 mg/kg) and thiopental (5 mg/kg), a combination of ketamine (25 mg/kg) and propofol (10 mg/kg), or control (saline). Fluoro-Jade staining revealed neurodegeneration 24 h after treatment. The behavioral tests--spontaneous behavior, radial arm maze, and elevated plus maze (before and after anxiolytic)--were conducted on mice aged 55-70 days. RESULTS: Coadministration of ketamine plus propofol or ketamine plus thiopental or a high dose of propofol alone significantly triggered apoptosis. Mice exposed to a combination of anesthetic agents or ketamine alone displayed disrupted spontaneous activity and learning. The anxiolytic action of diazepam was less effective when given to adult mice that were neonatally exposed to propofol. CONCLUSION: This study shows that both a gamma-aminobutyric acid type A agonist (thiopental or propofol) and an N-methyl-D-aspartate antagonist (ketamine) during a critical stage of brain development potentiated neonatal brain cell death and resulted in functional deficits in adulthood. The use of thiopental, propofol, and ketamine individually elicited no or only minor changes.