Pressure control and treatment interact in the deterioration of incidental visuospatial memory in hypertensive patients

BACKGROUND

Systemic hypertension (SH) is the main risk factor to cognitive deterioration, whereas visuospatial memory is more vulnerable to ageing. Some antihypertensive agents have a neuroprotector effect, however, such effects could be masked by comorbidities and/or the lack of effective control on the arterial pressure of patients.

OBJECTIVE

To assess this, the evaluation of incidental visuospatial memory of SH patients and the relation to the treatment received and the effective control of pressure were made.

METHOD

80 patients (46 woman) were included grouped by the received medication: angiotensin 2 receptor blockers (ARB) or angiotensin converting enzyme inhibitors (ACEI). A multiple correlation analysis between visuospatial scores and clinical variables was made; also, a mixed model analysis (fixed factors: treatment, pressure control, diabetes comorbidity; aleatory factors: age, schooling, months from SH diagnoses).

RESULTS

Half of the patients had a controlled pressure, from them the higher proportion received ARB, and a minor number of patients received ACEI. The normotensive patients receiving ACEI were inefficient whereas the hypertensive patients were more efficient. The systolic pressure was negatively related with the visuospatial scores in spite of no correlations occurred with MoCA and Raven tests.

CONCLUSIONS

The visuospatial incidental/intentional scores were negatively correlated with systolic pressure. The efficiency in the visuospatial ability depends on the interaction of treatment and effective control of blood pressure. The interaction between treatment and effective pressure control must be taken in count when cognitive deterioration is studied.

Neonatal exposure to monosodium glutamate disrupts place learning ability in adult rats

The activation of glutamatergic NMDA receptors of the hippocampus is closely associated with expression of place learning. Neonatal exposure to monosodium glutamate leads to abnormal expression of NMDA receptor subunits in the hippocampus, but its effect on place learning is unknown. Place learning acquisition and retrieval were assessed in mature adult rats after subcutaneous injection of monosodium glutamate (4 mg/g body weight) in eight neonatal rat pups at postnatal days one, three, five, and seven. Eight untreated rats were used as controls. At four months of age, the rats were challenged over a period of nine days with a place learning task. The task used an acquisition-retrieval paradigm in a Morris maze. Place learning acquisition was impaired in the experimental rats, which were unable to reduce their escape latencies during the nine training days. Controls improved between the fifth and ninth days of training. Test trials showed that retrieval of spatial information was also impaired in the experimental animals. These results show that both place learning acquisition and retrieval abilities in mature rats are impaired by neonatal treatment with monosodium glutamate. These findings may be related to the abnormal expression of NMDA receptor subunits in the hippocampus.

Density, but not shape, of hippocampal dendritic spines varies after a seizure-inducing acute dose of monosodium glutamate in rats

Dendritic spines are the main postsynaptic neuronal targets of excitatory inputs in cortical neurons, and both spine density and shape possess a well known adaptive synaptic-stimulation-dependent plastic capacity. Eighteen Sprague-Dawley adult male rats were used. Monosodium glutamate-treated rats (4 g/kg of body weight, i.p.) showed tonic and clonic epileptic seizures, as well as less dendritic spines in the apical arborization of their hippocampal CA1 pyramidal cells, compared to both control groups. No changes were seen in the proportional density of thin, stubby, mushroom-shaped, wide, or ramified spines between groups. Excessive glutamate-mediated excitatory activity on receptors could have led dendritic spines to shrink until they disappeared, while the spine-type proportion may be kept balanced as an adaptive response.