TITLE:
Neuropeptide Y Increases Both Ingestion of a Self-Selection Macronutrient Diet and Fos Expression in the Medial Amygdala of Rats
AUTHORS:
Bruna Mombach Dietrich, Marli Sita Scalcon, Franklin Back, Bárbara B. Philippi Martins, Elisa Cristiana Winkelmann-Duarte, Alberto A. Rasia-Filho
KEYWORDS:
Central Control of Appetite; Extended Amygdala; Feeding Behavior; Food Intake Behavior; Motivation
JOURNAL NAME:
Neuroscience and Medicine,
Vol.4 No.3,
September
10,
2013
ABSTRACT: The rat posterodorsal medial amygdala (MePD)
is responsive to the orexigenic neuropeptide Y (NPY) and is a putative candidate
to participate in neural circuits that modulate feeding behavior. Here, we studied
the effects of intracerebroventricular (icv) microinjection of NPY on the appetitive
and food intake behaviors of rats under the paradigm of the self-selection macronutrient
isolated diets [high-carbohydrate (high-CHO), high-protein and high-lipid food pellets].
At the same time, Fos expression was also evaluated in the MePD as a marker of local
cellular activation. Adult male rats received icv microinjections of NPY (1mg and10mg/5mL, n = 10 and 8, respectively) whereas the control
groups either received icv
microinjection of artificial cerebrospinal fluid (5mL, n = 8) or underwent sham procedure (n = 8). The data were obtained after a fasting
protocol. Feeding behavior was evaluated during a 2 h test period of free access to the selective
diets. Rats in all groups preferred the high-CHO diet. Compared to controls, both
doses of NPY increased the appetitive behaviors (searching for food and the frequency
of attempts to eat any diet) and the percentage of animals eating high-CHO diet.
However, only NPY at a dose
of 1 μg led to a significant increase in food intake and showed a strong positive
correlation with Fos expression in the MePD (p 0.05 in all cases). These new data reveal a biphasic
effect of NPY on
the appetite and food intake
behaviors and suggest that the MePD participates in the NPY-induced feeding behavior
in rats.