Amlodipine limits microglia activation and cognitive dysfunction in aged hypertensive mice

BACKGROUND

SBP and blood pressure variability are independent risk factors for cerebral small vessel disease, a leading cause for stroke and dementia. Calcium-channel blockers are known to reduce blood pressure variability and may thus offer benefit against dementia. Beyond this effect, the impact of calcium-channel blockers on hypertension-induced neuroinflammation, and especially, microglial phenotype remains unknown. We aimed to study the ability of amlopidine to alleviate microglia inflammation, and slow down cognitive dysfunction in aged hypertensive mice.

METHODS

Hypertensive BPH/2J and normotensive BPN/3J mice were studied until 12 months of age. Hypertensive mice were untreated or received amlodipine (10 mg/kg per day). Blood pressure parameters were measured by telemetry and tail cuff plethysmography. Mice underwent repeated series of cognitive tasks. Brain immunohistochemistry was performed to study blood-brain barrier dysfunction and microglial pro-inflammatory phenotype (CD68 + Iba1 + cells; morphological analysis).

RESULTS

Amlodipine normalized SBP over the entire life span and decreased blood pressure variability. BPH/2J mice exhibited impaired short-term memory that was prevented by amlodipine at 12 months (discrimination index 0.41 ± 0.25 in amlodipine-treated vs. 0.14 ± 0.15 in untreated BPH/2J mice, P  = 0.02). Amlopidine treatment of BPH/2J did not prevent blood-brain barrier leakage, a measure of cerebral small vessel disease, but limited its size. Microglia's inflammatory phenotype in BPH/2J, characterized by an increased number of Iba1 + CD68 + cells, increased soma size and shortened processes, was partly reduced by amlodipine.

CONCLUSION

Amlodipine attenuated the short-term memory impairment in aged hypertensive mice. Beyond its blood pressure lowering capacity, amlodipine may be cerebroprotective by modulating neuroinflammation.

Kindesmisshandlung

Child abuse is most often diagnosed by an emergency doctor on call who sometimes "feels" more than knows what he is confronted with. He should nevertheless always take a medical history and make a physical and radiological examination. X-ray imaging and an ophthalmologic retinal examination are the most important diagnostic steps. Typical findings are multiple and/or dorsal rib fractures, complex skull fractures, physeal fractures, all fractures within the first 12 months, multiple fractures in different localisations and stages of healing, all injuries with uncommon distributions, all patterned bruises, immersion burns, intramural hematoma and every unexplained loss of consciousness. The first step towards victim protection is always the removal of the abused child from its caregivers by admitting it to hospital, as 95% of all cases of reported child abuse take place within the child's family.