The Type of Fat in the Diet Influences the Behavior and the Relationship Between Cystinyl and Alanyl Aminopeptidase Activities in Frontal Cortex, Liver, and Plasma

Abstract

Insulin-regulated aminopeptidase (IRAP, cystinyl aminopeptidase, CysAP) and aminopeptidase M (alanyl aminopeptidase, AlaAP) are closely related enzymes involved in cognitive, metabolic, and cardiovascular functions. These functions may be modulated by the type of fat used in the diet. In order to analyze a possible coordinated response of both enzymes we determined simultaneously their activities in frontal cortex, liver, and plasma of adult male rats fed diets enriched with fats differing in their percentages of saturated, mono or polyunsaturated fatty acids such as sesame, sunflower, fish, olive, Iberian lard, and coconut. The systolic blood pressure, food intake, body and liver weight as well as glucose and total cholesterol levels in plasma were measured. The type of fat in the diet influences the enzymatic activities depending on the enzyme and its location. These results suggest cognitive improvement properties for diets with predominance of polyunsaturated fatty acids. Physiological parameters such as systolic blood pressure, food intake, and biochemical factors such as cholesterol and glucose in plasma were also modified depending on the type of diet, supporting beneficial properties for diets rich in mono and polyunsaturated fatty acids. Inter-tissue correlations between the analyzed parameters were also modified depending on the type of diet. If the type of fat used in the diet modifies the behavior and relationship between CysAP and AlaAP in and between frontal cortex, liver and plasma, the functions in which they are involved could also be modified.

The Type of Fat in the Diet Influences Regulatory Aminopeptidases of the Renin-Angiotensin System and Stress in the Hypothalamic-Pituitary-Adrenal Axis in Adult Wistar Rats

“…Our results differ with those of other works, where the CysAP activity is not significant and the AlaAP activity is opposite in the frontal cortex of animals fed diets with a higher proportion of MUFA (olive oil or Iberian lard) or SAFA (coconut), However, diets with similar proportions of MUFA/PUFA and low proportion of SAFA (fish or sesame oil) presented lower values of AlaAP activity [28] that would correspond more precisely to the membrane-bound fraction [64].…”

“…These metabolites are regulated by angiotensinase enzymes (Figure 1), among them we find the activities: aspartyl-AP (AspAP; EC 3.4.11.21), hydrolyzes Ang-I to form Ang 2-10; glutamyl-AP (GluAP or AP-A; EC 3.4.11.7), hydrolyzes Ang-II to form Ang-III; alanyl-AP (AlaAP or AP-M; EC 3.4.11.2) and arginyl-AP (ArgAP or AP-B; EC 3.4.11.6), in charge of transforming Ang-III into Ang-IV and Ang 4-8; cystinyl-AP or insulin-regulated AP (CysAP or IRAP; EC 3.4.11.3), which is recognized as the binding site for the Ang-IV receptor (AT4), which in turn shares catalytic centers for oxytocin and vasopressin [22][23][24][25][26][27]. Angiotensinases are known to be closely related to cognitive, metabolic and cardiovascular functions, but the type of fat in the diet can influence angiotensinases and, consequently, behavior [28]. RAS activation stimulates catecholamine and NPY secretion [29][30][31][32], furthermore, NPY itself is also capable of regulating catecholamine biosynthesis in the brain [33] and in the adrenal gland [34,35].…”