1998 Abstract: TPN AFFECTS HUNGER BUT NOT SATIETY IN FEMALE RATS. V. Kotha, M. Varma, Z -J Yang, C. Chen, and M.M.Meguid. Surgical Metabolism & Nutrition Laboratory, Dept Surgery, Syracuse NY 13210. 157
Abstracts 1998 Digestive Disease Week
#1061
TPN AFFECTS HUNGER BUT NOT SATIETY IN FEMALE RATS. V. Kotha, M. Varma, Z -J Yang, C. Chen, and M.M.Meguid. Surgical Metabolism & Nutrition Laboratory, Dept Surgery, Syracuse NY 13210.
TPN reduces appetite by decreasing sensation of hunger and increasing sensation of satiety and thus decreasing food intake(FI) via its action on the hypothalamus. FI is the product of meal size (MZ) and meal number (MN). A change in MZ or MN or both alters FI, because FI=MZ x MN. Since the size of a meal determines the onset of next meal MZ actually regulates satiety while the meal number regulates sensation of hunger. This suggests that MN and MZ are independently regulated via separate sensors in the hypothalamus. We previously showed that anorexia from cancer decreased food intake in male rats via a decrease in both MN and MZ while in female rats only by a decrease in MN. Anorexia of TPN in males is by a decrease in both MN and MZ. Since anorexia in female rats affects only MN as seen after cancer we hypothesised that TPN infusion in female rats would decrease the state of hunger (MN) and not satiety (MZ).
METHODS: 8 female Fischer -344 rat (145-170 g) received a TPN solution through a right Jugular vein catheter. The TPN solution provided 40 Kcal/day equivalent to 100% of daily caloric requirement. Food intake and feeding indices of MN and MZ were measured continuously via an Automated Computerized Rat Eater Meter. Data analyzed using ANOVA and *=p<0.5, significant.
RESULTS: TPN significantly decreased FI during dark and light phase and during 24 hrs. Decreased FI was due mainly to decreased MN during both dark and light phase and thus during 24 hrs.
Food Intake
Meal Number
Meal Size
dark
light
24 h
dark
light
24 h
dark
light
24 h
Pre TPN
7±1.1
1.6±0.3
8.7±1
10.3±0.9
3.4±0.7
13.7±0.9
0.6±0.4
0.5±0.2
0.6±0.3
TPN day 2
2.2±0.8*
0.5±0.3*
2.7±0.9*
2.7±1*
0.9±0.4*
3.6±1.2*
1.1±0.5
0.6±0.3
0.8±0.4
DISCUSSION: The mechanisms whereby TPN suppresses FI is via receptors in portohepatic area which relay nutrient information to the hypothalamus via hepatic vagal afferents. The decrease in FI via decreased MN suggests that in female rats TPN induced anorexia decreases hunger sensation without affecting satiety. The effect of TPN on hypothalamic neurotransmitters in female rats is currently under investigation in our laboratory.
Copyright 1996 - 1998, SSAT, Inc. Revised 29 June 1998.
