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Published on: April 21, 2017
[Cerebral blood flow and cerebrovascular reactivity in the early postnatal ontogeny of rats]
Insights
Cerebral blood flow (CBF) gradually increases in young rats but doesn't reach adult levels within the first month. However, cerebrovascular reactivity (CVR) to CO2 is well-developed early in postnatal life.
Area of Science:
- Neuroscience
- Physiology
- Developmental Biology
Context:
- Early postnatal development is critical for brain maturation.
- Understanding the development of cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) is essential for assessing brain health.
- Wistar rats were used to model early postnatal ontogenesis.
Purpose:
- To investigate the developmental trajectory of cortical CBF and CVR in Wistar rats from early postnatal life up to 25 days.
- To determine when mature cerebrovascular regulatory mechanisms are established.
- To correlate CBF changes with brain vessel growth during ontogenesis.
Summary:
- Cortical CBF increased progressively in Wistar rats during the first 25 days of postnatal life, peaking around days 9-11, likely due to rapid brain vessel growth.
- CBF did not reach adult levels by the end of the first month.
- Cerebrovascular reactivity (CVR) to a 5% CO2 challenge was robust and comparable to adult levels from the early postnatal period, indicating mature vascular regulatory mechanisms.
Impact:
- Reveals that while CBF maturation is a gradual process, the brain's ability to regulate blood flow in response to metabolic demands is established early in postnatal life.
- Provides crucial insights into the developmental neurobiology of cerebrovascular function.
- Suggests that early-life insults affecting vascular development may have long-lasting consequences on brain health.
Abstract:
The development of cortical cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) were studied in Wistar rats during early postnatal ontogenesis, in groups aged 2-5, 6-8, 9-11, 12-15, 16-18 and 19-25 days. CBF was measured polarographically using inhaled hydrogen clearance method, with platinum electrodes inserted into parietal cortex. At the mentioned age periods, CBF and its percentage of adult level averaged as 38 (21%), 81 (45%), 142 (78%), 85 (47%), 110 (61%), and 118 (65%) ml/100 g/min, respectively. Hence, during the early postnatal ontogenesis CBF increased gradually, however, it did not reach the adult level up to the end of the first month. CBF peak at 9-11 days period is suggested as a result of sharp rise of the brain vessels growth. CVR was assessed as the percentage of CBF increase after standardized 5% CO2 inhalation test. At the above age periods, CVR was found to bi 26, 33, 36, 41, 44 and 31% respectively, and was similar to adult rat CVR of 36%. The conclusion was drawn that regulatory mechanisms of adequate responses of brain vasculature to chemical metabolic factors are well developed already at the very beginning of postnatal life.
