Somatostatin alters intake of amino acid-imbalanced diets and taste buds of tongue in rats

Abstract

The present studies were designed to evaluate a potential dose-dependent effect of somatostatin (SRIF) administered peripherally on intake of either a low-protein basal diet or threonine-imbalanced diet (THR-IMB), on body weight gain (DeltaBW), gut motility, and on the histology of taste buds in rats. SRIF administration had a dual effect related to its concentration, increasing the intake of THR-IMB diet at low concentration and decreasing THR-IMB diet at high concentration. During the light phase, SRIF treatment increased the intake of THR-IMB diet, suggesting that the usual anorectic effect induced by intake of THR-IMB diet was attenuated. High-dosage SRIF decreases gastrointestinal motility, which, in turn, can decrease food intake and DeltaBW. The combination of THR-IMB diet regimen and SRIF treatment also induced significant modifications on the taste buds of the tongue. The feeding response to an amino acid-imbalanced diet includes a learned aversion to the diet, and animals may use taste in establishing that aversion. Modifications of taste buds of SRIF-treated rats eating THR-IMB diet might explain the increase of imbalanced diet intake if treated rats perceive this food as less aversive.

The rs1466113 Polymorphism in the Somatostatin Receptor 2 Gene Is Associated with Obesity and Food Intake in a Mediterranean Population

“…Thus, it has been shown that in rats somatostatin-containing interneurons are widely distributed in the anterior piriform cortex, an area thought to be responsible for the perception and recognition of essential amino acid levels in the diet [27] . Accordingly, Scalera [28] reported a dose-dependent effect of somatostatin, administered peripherally, on intake of either a low-protein basal diet or threonine-imbalanced diet, on body weight gain, gut motility and on the histology of taste buds in rats. However, as this is the first time that we have found this association with protein intake, it cannot be discarded that this may just be a random observation and may not hold up to replication in other samples.…”

Characterizing the neuropeptide pathways between the forebrain and the pons.

“…To the best of our knowledge the action(s) of CRH and Sst on gustatory neurons in the PBN has not been determined; however, in several other brain regions the influence of CRH on neural activity is predominately excitatory (Blank et al, 2003;Kash et al, 2008;Lowry et al, 2000;Ugolini et al, 2008), while that for Sst is inhibitory (Chieng and Christie, 2010;Connor et al, 2004;Jacquin et al, 1988;Saleh and Cechetto, 1993;Saleh and Cechetto, 1995). Centrally administered CRH has been shown to diminish food intake in a variety of species (Fekete et al, 2007;Jones et al, 1998;Parrott, 1990), while Sst administration increases intake and taste preference (Karasawa et al, 2014;Scalera, 2003;Stengel et al, 2010). Furthermore, injections of CRH into the PBN inhibits sodium appetite, while a CRH receptor antagonist has the opposite effect, increasing sodium chloride intake (Silva et al, 2006).…”

“…The peptides CRH and Sst have centrally mediated actions on autonomic function and ingestive behavior (Benoit et al, 2000;Feifel and Vaccarino, 1990;Feifel and Vaccarino, 1994;Fisher and Brown, 1993;Jones et al, 1998;Karasawa et al, 2014;Scalera, 2003;Spina et al, 1996;Stengel et al, 2010). Although the pathways mediating these effects are not well understood, they likely involve parallel regulation of the flow of gustatory and visceral sensory information to forebrain structures.…”

“…Our initial estimation was that most of these GABAergic terminals target non-GABAergic neurons in the PBN, which was the main reasoning behind our prediction that these PBN neurons project to brain regions outside of the PBN. Because somatostatin acts in the brain to influence feeding and taste preference (Karasawa et al, 2014;Scalera, 2003;Stengel et al, 2010), this discovery of a major inhibitory pathway from the CeA to the PBN will certainly encourage future studies to characterize the exact physiological function of somatostatin within central taste circuitry.…”

“…Thus, these specific peptidergic pathways may play an important role in regulating taste responses in the PBN. Both Sst and CRH have been shown to influence food intake and/or taste preference (Bassant et al, 2005;Ciccocioppo et al, 2003;Feifel and Vaccarino, 1990;Feifel and Vaccarino, 1994;Fekete et al, 2007;Heinrichs et al, 1993;Heinrichs and Richard, 1999;Karasawa et al, 2014;Parrott, 1990;Scalera, 2003;Stengel et al, 2010). Indeed, injection of CRH into the PBN disrupts expression of a sodium appetite in rats, while injections of a CRH receptor antagonist had the opposite effect, increasing sodium chloride intake (Silva et al, 2006).…”