**3. The working ability after administration of glucose, sucrose or fructose in young women**

Female college students participated in the experiments. They took Uchida-Kraaepelin tests and drank solutions containing glucose, sucrose, fructose or water as controls.

### **3.1 Uchida-Kraepelin tests**

There are numbers of a digit lined. Two numbers lined together are added [24, 25]. The number of the higher digit is described. This procedure is repeated for 1 min. Then the addition of numbers of the second line was performed, and repeated for 15 min. The total numbers added are calculated, and the numbers are compared before and after the experiment.

The working duty of 1 min. Was repeated 15 times then drinks were taken. After blood measurements at 30 min. Tests were repeated.

**Figure 6** shows that the working ability was significantly higher after the administration of sucrose, although there was a tendency for the working ability to increase after glucose or fructose administration, but not significantly.

We examined correlation coefficients between blood glucose levels and the working ability. Although there tends to be increase in the working ability with increase in blood glucose levels, but not significant.

**Figure 6.** *Relationship between sugar administration and the working ability.*

*Roles of Glucose and Sucrose Intakes on the Brain Functions Measured by the Working Ability… DOI: http://dx.doi.org/10.5772/intechopen.99203*

## **4. Transportation of tryptophan to the brain and conversion to serotonin**

Central serotonergic neurons play important roles in a variety of functions in animals and humans (see Review [26]).

We wanted to know if serotonin affects feeding by using injection of MAO inhibitor such as tranylcypromine (TC) intra peritoneally or by microinjection of TC into the hypothalamus.

At first, we injected TC intraperitoneally into rats and measured changes in body weights and foods intake [27].

**Figure 7** shows that after the injection of TC in rats body weights decreased and amounts of food intakes decreased significantly.

**Figure 8** shows that micro infusion of TC solution into the paraventricular nucleus of hypothalamus resulted in dramatic decrease of food intakes and body weight. These data suggest that serotonin inhibited feeding.

**Figure 7.** *Growth curves of rats administered with TC or vehicle.*
