Effect of post-prandial hyperlipidaemia on cerebrovascular function: gender difference?

Background: The consumption of a high-fat meal is characterised by a state of post-prandial hyperlipidaemia (PPH) with an exaggerated increase in triglycerides (Tg) that peaks at 4 hours. We recently demonstrated that PPH was associated with impaired cerebrovascular reactivity in aged, but not young males. However, to what extent PPH impacts the cerebral circulation in females, who are more prone to cognitive decline and dementia in later life, remains to be established.
Methods: Eighteen males (age: 24 ± 6 years; body mass index (BMI): 23.2 ± 3.6 kg.m2) and 8 females (age: 21 ± 2 years; BMI: 23.7 ± 3.1 kg.m2) participated in the study. Cerebrovascular function and Tg were assessed prior to, and 4 hours after the consumption of a standardised high-fat meal. Middle cerebral artery velocity (MCAv; transcranial Doppler ultrasound), mean arterial pressure (MAP; photoplethsmography) and end-tidal CO2 (capnography) were continuously recorded throughout each testing session. Serum Tg were determined via established methods from venous samples obtained from an indwelling cannula. MCAv and MAP were assessed following 5 minutes of seated rest. Cerebrovascular reactivity to carbon dioxide was assessed in response to 3 minutes of breathing 5% CO2 (balanced air; CVRCO2HYPER) and following 3 minutes of controlled hyperventilation (15 breaths per minute; CVRCO2HYPO). Cerebrovascular range (CVRCO2RANGE) was calculated as CVRCO2HYPER + CVRCO2HYPO. Data were analysed using a 2-way repeated measures ANOVA and Bonferonni corrected paired sample t-tests and independent sample t-tests. Significance was established at P < 0.05 and data are expressed as mean ± SD.
Results: At baseline, females were characterised by elevated MCAv, CVRCO2HYPER, CVRCO2HYPO and CVRCO2RANGE compared to the males (Table; all P < 0.05). During PPH, Tg increased relative to baseline in both groups and was associated with impaired CVRCO2HYPER and CVRCO2RANGE (Table; P < 0.05). Though this was independent of gender (Table; P > 0.05). Furthermore, PPH did not influence changes in resting MCAv or MAP (Table; P > 0.05).
Conclusion: Contrary to our previous findings, PPH has the capacity to impair cerebrovascular function in young adults. Though, it appears to be independent of gender. These observations are important given that a reduction in CVRCO2 may enhance the risk of stroke and neurodegenerative disease.