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Metabolic maturation of the brain: a study of local cerebral glucose utilization in the developing cat
H T Chugani1, D A Hovda, J R Villablanca
1Department of Neurology, UCLA School of Medicine 90024.
Insights
This study maps local cerebral metabolic rates for glucose (lCMRglc) in developing kittens, revealing distinct metabolic maturation patterns in brain regions correlating with behavioral development and critical periods.
Area of Science:
- Neuroscience
- Developmental Biology
- Animal Models
Background:
- Previous PET studies established dynamic local cerebral metabolic rates for glucose (lCMRglc) maturation in children.
- Understanding these maturational trends is crucial for developing animal models to study brain development.
Purpose of the Study:
- To establish a feline animal model for studying brain maturation.
- To characterize the developmental trajectory of lCMRglc in kittens from birth to adulthood.
- To correlate metabolic maturation with neuroanatomical development and behavioral emergence.
Main Methods:
- Quantitative [14C]2-deoxyglucose autoradiography was used to measure lCMRglc in kittens at various postnatal stages and in adult cats.
- Brain regions were analyzed for metabolic activity across different developmental time points.
Main Results:
- Kittens exhibited very low lCMRglc in early life, with older brain regions maturing faster than newer ones.
- A significant increase in lCMRglc occurred between 15 and 60 days, coinciding with synaptic proliferation.
- A secondary peak in lCMRglc at 180 days (sexual maturation) was observed before reaching adult levels, showing good correlation with region-specific behaviors and critical developmental periods.
Conclusions:
- The study successfully developed a kitten model to study lCMRglc maturation.
- Feline brain metabolism follows a complex developmental curve with distinct phases.
- These baseline data are essential for future studies on plasticity and the effects of lesions on brain development.
Abstract:
Previously, using positron emission tomography (PET), we showed that local cerebral metabolic rates for glucose (lCMRglc) in children undergo dynamic maturational trends before reaching adult values. In order to develop an animal model that can be used to explore the biological significance of the different segments of the lCMRglc maturational curve, we measured lCMRglc in kittens at various stages of postnatal development and in adult cats using quantitative [14C]2-deoxyglucose autoradiography. In the kitten, very low lCMRglc levels (0.14 to 0.53 mumol min-1 g-1) were seen during the first 15 days of life, with phylogenetically older brain regions being generally more metabolically mature than newer structures. After 15 days of age, many brain regions (particularly telencephalic structures) underwent sharp increases of lCMRglc to reach, or exceed, adult rates by 60 days. This developmental period (15 to 60 days) corresponds to the time of rapid synaptic proliferation known to occur in the cat. At 90 and 120 days, a slight decline in lCMRglc was observed, but this was followed by a second, larger peak occurring at about 180 days, when sexual maturation occurs in the cat. Only after 180 days did lCMRglc decrease to reach final adult values (0.21 to 2.04 mumol min-1 g-1). In general, there was good correlation between the metabolic maturation of various neuroanatomical regions and the emergence of behaviors mediated by the specific region. At least in the kitten visual cortex, which has been extensively studied with respect to developmental plasticity, the "critical period" corresponded to that portion of the lCMRglc maturational curve surrounding the 60-day metabolic peak. These normal maturational lCMRglc data will serve as baseline values with which to compare anatomical and metabolic plasticity changes induced by age-related lesions in the cat.