Taste responses of the facial and glossopharyngeal nerves to amino acids in the rainbow trout

Abstract

No significant differences were noted between responses of rainbow trout Oncorhynchus mykiss facial and glossopharyngeal nerves to 15 amino acids. Nine of these amino acids tested at 10 2  were stimulatory, whereas only two tested at 10 3  were effective gustatory stimuli. For both nerve systems, c10 3  -proline was the most stimulatory amino acid, with an estimated threshold of 10 7 ; however, --amino--guanidino-propionic acid (estimated threshold of 3 10 3 ), was the most potent compound at 10 2 . These results indicate that the same amino acids activate taste buds innervated by facial and glossopharyngeal nerves, respectively, and suggest that the same amino acids can be important in chemosensory feeding behaviour in the rainbow trout. 2001 The Fisheries Society of the British Isles

Feeding Stimulation Ability and Central Effects of Intraperitoneal Treatment of L-Leucine, L-Valine, and L-Proline on Amino Acid Sensing Systems in Rainbow Trout: Implication in Food Intake Control

“…For this reason, the taste spectra of amino acids eliciting stimulatory or deterrent feeding responses is highly species-specific ( Hara, 1994 ; Morais, 2017 ). Salmonids, including rainbow trout, belong to a group of teleosts which show a narrow range of taste response, responding only to a few amino acids ( Marui et al, 1983 ; Hara, 1994 ; Kohbara and Caprio, 2001 ).…”

“…Therefore, we decided to evaluate the feeding response to leucine and valine by performing a feeding trial in the present study, which should link to their hedonic value. We have also extended this work to include proline, as it has been reported as the most potent amino acid eliciting a gustatory response in both electrophysiological ( Marui et al, 1983 ; Kohbara and Caprio, 2001 ) and behavioral ( Jones, 1989 ) studies with rainbow trout.…”

Gustatory responses to feeding‐ and non‐feeding‐stimulant chemicals, with an emphasis on amino acids, in rainbow trout

“…Although the maxillary branch of the palatine nerve contains both trigeminal and communis components, the former generally shows little or no chemical sensitivity (Kiyohara et al ., 1975), suggesting that signals due to chemical stimulation are transmitted solely by the latter. In further support of this, the present amino acid relative effectiveness is similar to that obtained from the glossopharyngeal nerve (IX) that lacks trigeminal fibres (Kohbara & Caprio, 2001). Previous finding that two distinct fibre types exist in the rainbow trout maxillary nerve (Yamashita et al ., 1989) further suggests that multiple gustatory cell types constituting a taste bud, or taste bud types may exist innervated by different fibre types.…”

“…Also relevant here is the fact that CO 2 , via the gustatory system, not only functions as a repellent but causes immediate reduction of the ventilatory movement in fishes (Konishi et al ., 1969; Jones et al ., 1985; Yamashita et al ., 1989). This adaptive reaction to CO 2 , combined with a striking similarity of the response profiles between the facial (VIIth) and glossopharyngeal (IXth) systems (Kohbara & Caprio, 2001), suggests that the fish gustatory system may also function as a sensor for the peripheral ventilatory regulatory centre. Although ventilation in fishes is driven by requirement for O 2 uptake, increasingly, experimental evidence suggests that a significant CO 2 and pH‐keyed ventilatory drive also exists in fishes (Gilmour, 2001).…”

Incorporation of Rapa Whelk (Rapana venosa) meal in diets for rainbow trout (Oncorhynchus mykiss) fry

“…Various stimulants and attractants are widely applied to contribute this feature to feeds, particularly in scientific studies where vegetable protein sources are used as alternatives in fish feeds (Al‐Souti et al., 2019). For instance, it is stated that krill meal is used as a chemoattractant in shrimp diets (Saleh et al., 2018), fish silage in white pacific shrimp diets, whereas amino acids such as alanine, hydroxyproline, phenylalanine, leucine, partially proline and nucleotides are considered as chemoattractants for rainbow trout (Kohbara & Caprio, 2001; Marui et al., 1983). In this study, it is presumed that the reason for fish not to prefer snail meal‐based diets as compared to the control diet depends upon a different reason, considering all the amino acids that are recognized to be attractive for rainbow trout were present in the feed above the minimum requirements for the fish.…”