Introduction

In 1998, the Calorie Control Council estimated that 144 million American adults regularly consume low-calorie, sugar-free products.

To date the U.S. Food and Drug Administration have approved five sugar substitutes, one of them being aspartame.

Purpose The purpose of this study, is to determine the effects of

aspartame consumption on fat deposition in C. elegans as a potential indication of aspartame activation of the cephalic

response.

Hypotheses Hypothesis #1: The starved (lean) C. elegans will demonstrate no difference in fat

deposition between groups.

Hypothesis #2: Supplementation of aspartame will lead to an increase in fat deposition due to a cephalic response.

Cephalic Phase Response

Giduck (1987) found that oropharyngeal - stimulated responses are reliably initiated by the taste and smell of food.

Nicolaidis (2003) suggests that cephalic responses play an important role in the regulation of both digestive and metabolic processes and act to optimize the utilization of the ingested nutrients.

Salivary SecretionsSalivary Secretions The sight, smell, thought or taste

of food initiates the cephalic response through salivating.

Blood sugar levels decrease.

The sight, smell, thought or taste of food initiates the cephalic response

through salivating. Blood sugar levels decrease.

Gastric SecretionsGastric Secretions Dive – like mechanism is stimulated in

the brain which creates a greater desire for food.

Originates from the cerebral cortex and appetite centers of the brain which

are mediated by the vagus nerve.

Dive – like mechanism is stimulated in the brain which creates a greater desire

for food. Originates from the cerebral cortex

and appetite centers of the brain which are mediated by the vagus nerve.

Literature Review

Ashrafi (2007) and Rankin (2005) found that due to the chemo sensitivity and cephalic response system in C. elegans, they are an ideal organism for the study of

energy balance (fat deposition).

Methodology

Sudan Black Staining & Nomarski Optics Used for the identification of fat deposits in C.elegans intestines

Glucose Supplemented N2 Aspartame Supplemented N2Control Starved N2

N2 Strain Caenorhabditis elegans (n=30)

Pilot Studies Conducted prior to experimentation in order to determine the

needed concentrations of glucose and aspartame for the axenic liquid medium (10%).

Statistical Analysis - ANOVA (Sheffe Post Hoc) (p<.05)

Mean + SD

Fat Deposition Measurements (Photoshop)

Relative Luminosity Evaluation

This bar graph demonstrates the dark pixel mean (from the Adobe Photoshop Histogram Function) of the control group (68.44 + 1.74), glucose supplemented group (69.18 + 1.29)

and the aspartame supplemented group (62.77 + 1.59).

Images of the stained C. elegans were evaluated for relative luminosity. Regions of black pixels in the image (representing areas of fat deposition) were compared to the lighter areas

of negligible fat deposition. The dark pixel mean of the image was reported and used for statistical analysis of the overall fat deposition.

Control Starved C. elegans(Mean = 62.89 dark pixels)

Glucose Supplemented C. elegans(Mean = 71.56 dark pixels)

Aspartame Supplemented C. Elegans(Mean = 60.22 dark pixels)

Discussion I An early limitation of the study included a non-

sterile laboratory environment. Contamination of C. elegans cultures created a food source from

which the worms would feed, essentially prolonging their lifespan.

Additionally, there was an inability to precisely record the absorption of the glucose and the

aspartame by the C. elegans.

Discussion II The mean fat deposition of each group reflects the starved worms compensating for negligible

calories by storing more fat.

The glucose supplemented worms deposited fat by consuming excess calories from

the glucose.

The aspartame supplemented worms deposited the least amount of fat since aspartame is not a

source of energy which the C. elegans could feed off of.

The one-way ANOVA followed by a Sheffe Post Hoc (p<.05) revealed a significant difference

between the control and glucose supplemented groups and the glucose and aspartame

supplemented groups. No significant differences were found between the control and glucose

supplemented groups.

Conclusion This study rejects hypothesis #1 due to

differences in fat deposition found between the C. elegans groups as previously

mentioned.

This study also rejects hypothesis #2 since supplementation of aspartame does not lead to increased fat deposition. It is believed that this may be due to a lack of available energy

sources in the aspartame group.

Future Studies Possible future studies could include…

Incorporating the no-calorie sweetener Sucralose (Splenda) into future trials and observing subsequent fat deposition.Training C. elegans in an aspartame feeding environment and transferring them into a glucose

feeding environment to measure fat deposition.

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