The Food Entrainable Oscillator: The Ghrelin and Growth Hormone Secretagogue Story

Investigating the Role of the Growth Hormone Secretagogue Receptor in Food-Motivated Behaviours

“…As ghrelin increases under times of FR or caloric restriction (i.e. following a fast or in a sustained negative energy balance) (Horvath et al 2001;Wellman and Abizaid, 2015), and in response to anticipation of a scheduled meal (Cummings et al, 2001;Drazen et al, 2006;Khazall, 2017), it is likely that this elevation in ghrelin enhanced food motivated behaviours in WT rats, but not in the GHSR m1/Mcwi rats, which do not respond to circulating ghrelin (MacKay et al, 2015). The bolstering of the motivational state due to FR could have contributed to the differences in behaviours between genotypes in the sucrose studies.…”

“…Although Bake et al (2012) did not find alterations in NPY expression, they did not examine GHSR mRNA dynamics, and it is possible that upregulation of GHSRs on NPY neurons, and subsequent second-order inhibition of POMC/CART neurons, may enhance consumption of HFD during a binge in WT mice. Indeed, recent data from our laboratory suggest that GHSR is upregulated in the ARC in anticipation of a scheduled palatable meal from Day 4 through to Day 9 of scheduled treat access (Khazall, 2017) and increased sensitivity to ghrelin could enhance intake, via potentiation of NPY/AgRP activity.…”