Sodium depletion enhances salt palatability in rats

“indicates that these facial movements are more related to stereotyped fixed action patterns of ingestio”

“…rats (Grill & Berridge, 1985), and indeed, they behave in a manner compatible with the role required by Dickinson and colleagues of their hedonic system, such as tracking motivational state directly (Berridge et al., 1981; Berridge et al., 1984; Berridge, 1991; Berridge & Robinson, 1998, p. 314).”

“, "thalamic" transection below the telencephalon (64); neuron death in the substantia innominataJventral pallidum (38); sodium appetite (9,52,54); etc.”

“tion (Berridge et al., 1984; Berridge, 1991), similar to the way human subjective ratings of taste palatability are increased by those states (Cabanac, 1979; Beauchamp et al.”

“For example, if the positive hedonic impact of a stimulus is reduced, either by changing the taste itself, or by reducing the relevant physiological appetite state [8,13,21,23], or by training a learned aversion for the taste [51,55], or by neural or pharmacological disruption of hedonic processing [9,27,57,84], then…”

“…a strong salt appetite state is induced, the UCS taste of intense saltiness suddenly becomes pleasant, no longer eliciting gapes and instead evoking positive facial expressions such as lip licking, just as does the taste of sucrose (Berridge et al., 1984; Flynn et al., 1991; Tindell et al., 2006).”

“Ventral pallidum neurons thus pass the most stringent test for hedonic coding that is dis-confounded from sensory coding: being able to track hedonic shifts of a single sensory stimulus from nasty to pleasant [116,175,180,181].”

“…response patterns were later scored off-line in slow motion (frame by frame to 1/10th actual speed) by a trained observer who was blind to experimental condition, using time bin scoring procedures developed to assess hedonic vs aversive taste valuations (Berridge et al, 1984; Berridge, 2000).”

“Conversely, bitter tasting quinine or highly concentrated sodium chloride both elicit similar aversive ‘‘disgust’’ reaction patterns, and both are avoided compared to water (Berridge et al., 1984).”

“1993, 1995), the palatability of salt varies inversely with its availability to the body, and it is believed to be the primary mechanism driving increased Na intake (Denton, 1982; Berridge et al. 1984; Berridge & Schulkin, 1989; Epstein, 1991; Schulkin, 1991; Johnson & Thunhorst, 1997).”

“Conversely, different affective reactions may be elicited by tastes that are equally preferred, so long as a constant balance between hedonic and aversive reactions is kept (Berridge & Grill, 1984).”

“Neural firing rate to salt is as high as it is to sucrose (middle).”

“The reduction of NaCl consumption observed after treatment with the highest dose (3.0 mg/kg) of SR-141716A could be explained by the fact that in Na-depleted rats, the intake of 2%NaCl is influenced, albeit marginally, by taste-related hedonic factors (Berridge et al. 1984).”

“Hedonic, aversive, and neutral taste reactivity response patterns were scored using time bin scoring procedures developed to assess hedonic vs. aversive taste valuations (Berridge 2000; Berridge et al. 1984), with Observer software (Noldus, Netherlands).”

“Moreover, exposure to concentrated saline normally elicits a mixture of aversive and appetitive responses, but this swaps to an entirely appetitive sequence when animals are tested in a state of salt deprivation (eg, Berridge, Flynn, Schulkin, & Grill, 1984 ).”

“5 M) can produce hedonic reactions in a salt depleted state [19, 33,93,118].”

“Keywords: voltammetry, electrophysiology, conditioned taste aversion, taste reactivity, reward, ventral tegmental area”

“In this state, both the palatability (45) and the neural coding of a normally aversive salty taste in the VP (46) change to resemble the normal response to an appetitive sweet taste.”

“In the presence of sodium hunger, the facial response shifts towards a taste reaction seen during sweet taste experience, and the rat avidly ingests concentrated sodium or a gustatory stimuli formerly associated with sodium such as quinine (Berridge & Schulkin, 1989; Berridge et al., 1984).”

“Berridge, Flynn, Schulkin, and Grill [118] have demonstrated that sodium depletion significantly enhances positive appetitive responses (e.g., lateral tongue protrusions, paw licking) to 0.5 M saline [118,119].”

“However, sodium depletion in rats elicits salt appetite whereby affective reactions to this very same salty taste suddenly flip from negative to positive, and hedonic tongue protrusions are observed instead of aversive gapes [13–15].”

“, 1993), and palatability is believed to be the device linking bodily deficit to appetitive behavior (Denton, 1982, 1991; Dietz et al., 2006; Berridge et al., 1984; Berridge and Schulkin, 1989; Epstein, 1991; Johnson and Thunhorst, 1997; McCaughey and Scott, 1998; Rozin and Schulkin, 1990; Schulkin, 1982, 1991; Tindel…”

“…sour, and bitter tastes, respectively (Norgren 1990; Smith and St John 1999); the former two are palatable to rats, and the latter two are aversive, although CA is a complex taste that induces both positive and negative responses (Berridge et al. 1984; Breslin et al. 1990; Myers and Sclafani 2003).”

“…taste is flipped to hedonically ‘liked’ via induction of a salt appetite (diuretic injections that induce a physiological state of sodium depletion) (Berridge et al., 1984), the ventral pallidum neurons begin firing to it with similarly high frequency as to the sweet sucrose taste (Tindell et…”

“…(“taste reactivity”; Grill and Norgren, 1978b), despite the fact that the latter are often used to measure large differences in palatability (Berridge et al., 1984), because taste reactivity is unlikely to be sensitive enough to reliably measure the reliable but subtle palatability…”

“…whether the taste object is worthy of consumption; this psychological property is exquisitely sensitive to a large range of experiential variables (Berridge et al., 1984; Galef, 1986; Spector et al., 1988; Breslin et al., 1993; Fortis-Santiago et al., 2010), and as such can only be made…”

“Collectively, these mechanisms should result in a selective, macronutrient-specific appetitive drive (motivation), which results in the correct selection from a menu, as demonstrated for Na intake((8,10,11)).”

“It appears that salt appetite is associated with a form of reward reevaluation where salty substances are wanted and liked more than salt-lacking rewards [3, 6, 90].”

“Pontine Gustatory Activity Is Altered by Electrical Stimulation in the Central Nucleus of the Amygdala”

“For example, repeated exposures to hypertonic NaCI produced a gradual reduction in the number of elicited ingestive FAPs while the number of aversive FA Ps remained constant (Berridge et al., 1984).”

“5 M) evoke a mixture of appetitive and aversive taste reactivity that switches to entirely appetitive following sodium depletion (26).”

“Even highly aversive tastes such as intense saltiness can become affectively positive with severe salt deprivation [60].”

“For example, rats deprived of sodium increase their preferences for solutions that contain this substance, even when the solution contains concentrations that are normally aversive.(11) When homeostatic levels of sodium are restored, their aversion to the hypertonic solutions returns.”

“In addition to goaldirected behaviors for acquiring salt, sodium deplete animals show exclusively appetitive taste reactivity to intra-oral infusions of hypertonic sodium in comparison to sodium replete rats that exhibit a mixture of appetitive and aversive taste reactivity (110).”

“Sodium depletion in humans and rats leads to an increased palatability of salt [2, 34], and it is known that ascent to high altitudes leads to sodium diuresis linked to a suppression of the renin-angiotensin-aldosterone system [42].”

“In two-bottle intake tests, rats showed an enhanced preference for hypertonic salt solution following sodium depletion, as shown previously (Berridge et al. 1984; Sakai et al. 1987).”

“Specifically, the high concentrations of NaCl that elicited aversive orofacial behaviors in normal rats, elicit ingestive behaviors when rats are salt deficient (Berridge et al., 1984).”

“palatable (Berridge et al., 1984; McCaughey et al., 2005), and there are also increases in taste-evoked excitation by CaCl2 or NaCl in Scells in the NST, but not in other neural subgroups (Jacobs et al.”

“These reactions are thought to reflect hedonic state (23, 28) because they are distinct for pleasant and unpleasant tastes; their presence (if not their exact motor sequences) is conserved across several mammalian species (including newborn humans), and they can be manipulated by experimentally altering the value of t…”

“Sodium depletion is characterized by the avid ingestion of salt solutions and a shift in the liking or palatability of those solutions ( Berridge, Flynn, Schulkin, & Grill, 1984 ).”

“…and reinforcer devaluation with LiCl (Adams 1982; Smith et al. 2012), although there are others, including high-speed rotation to induce nausea (Holland and Straub 1979) or outcome in fl ation bymeansofextendedfooddeprivation(Quinnetal.2013)ornutri-ent depletion (Berridge et al. 1984; Tordoff 2001).”

“Following this bout, the EMG signal becomes dominated by mouth movements reflecting the palatability of the taste, which is the degree to which the tastant is pleasant or aversive (Berridge et al., 1984; Travers and Norgren, 1986; Spector et al., 1988).”

“well documented with rats [37] and within the human literature [21,22,27].”

“Accompanying the change in intake behavior observed in sodium deplete animals is a marked increase in the palatability of NaCl (Berridge et al., 1984).”

“…responsiveness to reward-predictive signals under conditions in which securing the reward is essential to the survival of the organism as documented in a classical study showing that high concentrations of salt that are normally avoided become palatable to saltdeprived rats (Berridge et al., 1984).”

“Moreover, we note that palatability may also depend on the reinforcing value of sucrose, the animals’ internal state (Berridge et al., 1984) as well as learned postingestional effects associated to tastants (Aravich and Sclafani, 1980; de Araujo et al.”

“The taste reactivity test is a behavioral test that directly examines species typical responses to infused solutions, and has been validated in numerous studies [10, 23, 28].”

“Sodium-deprived rats change their orofacial response to hypertonic NaCl from a negative gape and chin scraping response to a more positive expression and do so on the first exposure to sodium salts after their first bout of sodium deficiency (3).”

“3 M NaCl in FURO+CAP treated rats is consistent with previous results demonstrating that animals with experimentally-induced salt appetite show enhanced ingestive and reduced rejection oro-facial and body behaviors [40,41].”

“A classic example is that a concentrated sodium solution that would normally be aversive is treated as palatable by salt-depleted rats (Berridge et al., 1984; Wagman, 1963).”

“…after dopamine D1-like and D2-like receptor antagonists generalise across rewards which can induce very different ingestive microstructural (Canu et al. 2010; Cooper and Higgs 2005; D'Aquila et al. 2012; Galistu and D'Aquila 2012) and taste reaction (Berridge et al. 1984, 1989) patterns.”

“This gustatory behavioral response, however, is modifiable by learning and immediate physiological state (5, 7).”

“When the same animals are salt depleted, however, this increased consumption of high molar salt is associated with a reversal from aversive reactions to liking reactions (Berridge et al. 1984; Clark and Bernstein 2006; Tindell et al. 2006).”