Ghrelin, peptide YY and their hypothalamic targets differentially regulate spontaneous physical activity

Metabolic profile and spontaneous physical activity modulation under short-term food restriction in young rats.

“…That glucose uptake by the oxidative muscles also leads to an increase in glycogen stores for heart and soleus, as found in our experiment. Therefore, observing the big picture of the metabolic status, FR forced the organism balancing and reallocating substrates to survive, showing a high efficiency on energy usage, corroborating with some authors statements 4,19 . Allthose modulations of metabolic and locomotor activity discussed above have been associated with neural communication, being the neuropeptide Y (NPY) and agouti-related peptide (AgRP) signals the most involved 27,28 .…”

“…In situations of negative energy balance NPY and AgRP activity increase 6 , however, during food restriction there is no possibility of feeding and it is possible that those signals persist. If correct, the consequences of chronically higher activity of NPY and AgRP in this case, with no food available, can be the inhibition of thermogenesis 24 and SPA 18 when trying to promote positive (or less negative) energy balance and maybe influencing the efficiency of energy usage 4,19 . In summary, our experiment showed that even short-term food restriction of 50% imposes significant modulations on the metabolic profile towards the use of energy stores preferably in oxidative tissues of young rats.…”

“…Therefore, efforts in order to identify the mechanisms involved in SPA regulation have been made 4 and despite the recognition of some peptides, hormones, their targets and communication 4 , the complex control of SPA currently remains under investigation 5,6,7 . Santos-Pinto 8 consistently postulated that the total daily energy expenditure, which is given by the sum of energy spent through thermic effect of food, resting metabolic rate and physical activity 9 , is modulated in relation to food intake 8 .…”

“…It has also been described that an acute increase of SPA during FR in rats is due to the increased activity hypothalamic neuropeptides, which is a transient behavior motivated by food seeking 18 and literature suggests that if FR is chronically maintained it leads to a decrease in SPA 18 . In this regard, an interesting idea of a mechanism to save energy in times of FR was proposed 8 , being recently improved by involving neuronal, endocrine and metabolic elements 4 . Whereas it is obvious that efficiency in fuel utilization of mammals is higher in long-term food restricted animals 19 , it is not clear whether differences regarding SPA also exist in short periods of FR.…”

Translational Science: How experimental research has contributed to the understanding of spontaneous Physical Activity and Energy Homeostasis

“…administration of NPY resulted in a shift of metabolism towards lipid storage and an increased use of carbohydrates, while at the same time increasing locomotor activity, energy expenditure, and body temperature 48 . Pfluger et al 49 observed the same increase of SPA following NPY i.c.v. administration.…”