Electrophysiological responses of single olfactory bulb neurons to amino acids in the channel catfish, Ictalurus punctatus

1995 ◽  
Vol 74 (4) ◽  
pp. 1421-1434 ◽  
Author(s):  
J. Kang ◽  
J. Caprio
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Olfactory Bulb ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Action Potentials ◽  
Recording Time ◽  
Over Time ◽  
Olfactory Bulb Neurons

1. Responses of 89 single olfactory bulb neurons from 43 channel catfish, Ictalurus punctatus, to amino acid odorants were recorded in vivo simultaneously with the electro-olfactogram (EOG). Recording time for individual neurons ranged from 16 to 344 min. The averaged spontaneous frequency ranged from x003C; 1 to 16 action potentials/s with a mean frequency of 5.2 +/- 3.6 (SD) action potentials/s. 2. Histological examinations of carbocyanine dye 1,1'diocadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-labeled olfactory bulbs and electrical stimulation of the olfactory tracts in a subset of experiments suggested that the majority of the recorded olfactory bulb neurons in this study were mitral cells. 3. Olfactory bulb neurons responded to amino acids with either an excitation or suppression of the background neural activity. Of the 337 stimulus applications, 28% of the responses were excitatory, and 33% were suppressive. The approximately 1:1 ratio of excitatory to suppressive responses for all stimulus applications suggests that suppressive responses also play important roles in the coding of odorant information in the channel catfish. 4. Responses of single olfactory bulb neurons were highly reproducible over time (up to 5 h). Responses to any amino acid never changed from excitation to suppression, or vice versa over time. 5. Single olfactory bulb neurons responded with excitation or suppression to more than one amino acid previously indicated to bind to independent receptors. 6. Estimated threshold concentrations for activation of an olfactory bulb neuron ranged from 10(-7) to 10(-3) M and were different from neuron to neuron for a particular stimulus and from stimulus to stimulus for a particular neuron. Responses of single olfactory bulb neurons to a given amino acid did not change from excitation to suppression, or vice versa, across different suprathreshold concentrations.

scholarly journals Odorant receptors activated by amino acids in sensory neurons of the channel catfish Ictalurus punctatus.

1993 ◽  
Vol 102 (6) ◽  
pp. 1085-1105 ◽  
Author(s):  
T T Ivanova ◽  
J Caprio
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Olfactory Receptor ◽  
Action Potentials ◽  
Single Channel ◽  
Odorant Receptors ◽  
Olfactory Neurons ◽  
Whole Cell

Odorant receptors activated by amino acids were investigated with patch-clamp techniques in olfactory receptor neurons of the channel catfish, Ictalurus punctatus. The L-isomers of alanine, norvaline, arginine, and glutamate, known to act predominantly on different olfactory receptor sites, activated nondesensitizing inward currents with amplitudes of -2.5 to -280 pA in olfactory neurons voltage-clamped at membrane potentials of -72 or -82 mV. Different amino acids were shown to induce responses in the same sensory neurons; however, the amplitude and the kinetics of the observed whole cell currents differed among the stimuli and may therefore reflect activation of different amino acid receptor types or combinations of receptor types in these cells. Amino acid-induced currents appeared to have diverse voltage dependence and could also be classified according to the amplitude of the spontaneous channel fluctuations underlying the macroscopic currents. A mean single-channel conductance (gamma) of 360 fS was estimated from small noise whole-cell currents evoked by arginine within the same olfactory neuron in which a mean gamma value of 23.6 pS was estimated from 'large noise' response to norvaline. Quiescent olfactory neurons fired bursts of action potentials in response to either amino acid stimulation or application of 8-Br-cyclic GMP (100 microM), and voltage-gated channels underlying generation of action potentials were similar in these neurons. However, in whole-cell voltage-clamp, 8-Br-cyclic GMP evoked large rectangular current pulses, and single-channel conductances of 275, 220, and 110 pS were obtained from the discrete current levels. These results suggest that in addition to the cyclic nucleotide-gated transduction channels, olfactory neurons of the channel catfish possess a variety of odor receptors coupled to different types of transduction channels.

Electrophysiological responses of single olfactory bulb neurons to binary mixtures of amino acids in the channel catfish, Ictalurus punctatus

1995 ◽  
Vol 74 (4) ◽  
pp. 1435-1443 ◽  
Author(s):  
J. Kang ◽  
J. Caprio
Keyword(s):  
Amino Acids ◽  
Olfactory Bulb ◽  
Binary Mixtures ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Electrophysiological Responses ◽  
Excitatory Responses ◽  
The Individual ◽  
First Time ◽  
Olfactory Bulb Neurons

1. For the first time in any vertebrate, responses of single olfactory bulb neurons to odorant mixtures were studied quantitatively in the channel catfish, Ictalurus punctatus. 2. Extracellular electrophysiological responses of 61 single olfactory bulb neurons from 36 channel catfish to binary mixtures of amino acids and to their components were recorded simultaneously with the electro-olfactogram (EOG). Tested were a total of 297 mixture trials consisting of 18 different stimulus pairs formed from 8 amino acids. 3. For 42% (126 of the 297) of the tests, no significant change (N) from spontaneous activity occurred. Responses to the remaining 171 tests of binary mixtures were excitatory (E; 29%) or suppressive (S; 29%). No response type was associated with any specific mixture across the neurons sampled. 4. Mixture interactions that changed response types (E or S) from those observed to the individual components were rare, because 89% of the responses of single olfactory bulb neurons to the tested binary mixtures were classified similarly as the responses to at least one of the components. 5. Responses of single olfactory bulb neurons were generally predictable for binary mixtures whose component responses were classified as both E, both S, and both N. For binary mixtures whose component responses were classified differently (e.g., one component evoked excitatory responses and the other evoked suppressive responses), the predictability of the response was dependent on the specific mixture type.

In Vivo Responses of Single Olfactory Receptor Neurons of Channel Catfish to Binary Mixtures of Amino Acids

1997 ◽  
Vol 77 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Jiesheng Kang ◽  
John Caprio
Keyword(s):  
Amino Acids ◽  
Binary Mixtures ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Olfactory Receptor ◽  
Olfactory Receptor Neurons ◽  
Electrophysiological Response ◽  
Receptor Neurons ◽  
First Time

Kang, Jiesheng and John Caprio. In vivo response of single olfactory receptor neurons of channel catfish to binary mixtures of amino acids. J. Neurophysiol. 77: 1–8, 1997. For the first time in any vertebrate, in vivo responses of single olfactory receptor neurons to odorant mixtures were studied quantitatively. Extracellular electrophysiological response of 54 single olfactory receptor neurons from 23 channel catfish, Ictalurus punctatus, to binary mixtures of amino acids and to their components were recorded simultaneously with the electroolfactogram (EOG). For 57% (73 of 128) of the tests, no significant change (N) from spontaneous activity occurred. Responses to the remaining 55 tests of binary mixtures were excitatory (E; 13%) or suppressive (S; 30%). No response type was associated with any specific mixture across the neurons sampled. Eighty-six percent of the responses of catfish olfactory receptor neurons to binary mixtures were classifed similar to at least one of the component responses, a percentage comparable (i.e., 89%) with that observed for single olfactory bulb neurons in the same species to equivalent binary mixtures. The responses of single olfactory receptor neurons to component-similar binary mixtures (i.e., component responses were both E, both S, and both N, respectively) were generally (80% of 59 tests) classified similar to the responses to the components. For E+N and S+N binary mixtures, the N component often (66% of 58 tests) reduced or concealed (i.e., “masked”) the excitatory and suppressive responses, respectively. For the majority (6 of 11 tests) of E+S binary mixtures, null activity resulted. Responses to the remaining five tests were either excitatory ( n = 3) or suppressive ( n = 2).

In vivo responses of single olfactory receptor neurons in the channel catfish, Ictalurus punctatus

1995 ◽  
Vol 73 (1) ◽  
pp. 172-177 ◽  
Author(s):  
J. Kang ◽  
J. Caprio
Keyword(s):  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Olfactory Receptor ◽  
Action Potentials ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons ◽  
Spontaneous Frequency ◽  
Excitatory Responses ◽  
First Time

1. We report for the first time in any teleost, a quantitative in vivo study of recordings from single olfactory receptor neurons (ORNs) in the channel catfish, Ictalurus punctatus, with odorant stimuli. 2. Responses of 69 spontaneously active single ORNs were recorded simultaneously with the electroolfactogram (EOG). Recording times ranged from 10 to 72 min per receptor cell with an average of 24 +/- 15 (SD) min/cell. The averaged spontaneous frequency ranged from < 1 to 12 action potentials/s with a mean frequency of 4.7 +/- 2.5 action potentials/s. 3. Catfish ORNs responded to the odorant stimuli (amino acids, bile salts, and ATP) with either an excitation or suppression of the background neural activity. Suppressive responses were encountered more frequently than excitatory responses, suggesting that suppressive responses also play an important role in olfactory coding. 4. Excitatory and suppressive responses to the different odorants were elicited from the same ORN, suggesting that different olfactory receptor molecules and different transduction pathways exist in the same ORN.

scholarly journals Processing of Bile Salt Odor Information by Single Olfactory Bulb Neurons in the Channel Catfish

2007 ◽  
Vol 97 (6) ◽  
pp. 4058-4068 ◽  
Author(s):  
S. H. Rolen ◽  
J. Caprio
Keyword(s):  
Olfactory Bulb ◽  
Bile Salt ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Bile Salts ◽  
Present Report ◽  
Side Chain ◽  
Steroid Nucleus ◽  
Molecular Features

A chemotopic map of biologically relevant odorants (that include amino acids, bile salts, and nucleotides) exists in the olfactory bulb (OB) of channel catfish, Ictalurus punctatus. Neurons processing bile salt odorant information lie medially within this OB map; however, information as to how single neurons process bile salt odorant information is lacking. In the present report, recordings were obtained from 51 OB neurons from 30 channel catfish to determine the excitatory molecular receptive range (EMRR) of bile salt responsive neurons. All recordings were performed in vivo within the medial portions of the OB using extracellular electrophysiological techniques. Excitatory thresholds to bile salts typically ranged between 0.1 and 10 μM. The bile salt specificity of OB neurons were divided into three groups: neurons excited by taurine-conjugated bile salts only (group T), neurons excited by nonconjugated bile salts only (group N), and neurons excited by at least one member of each of the three classes of bile salts tested (group G). In addition to the conjugating group at C24 of the side-chain, OB neurons discriminated bile salts by the molecular features present at three other carbon positions (C3, C7, and C12) along the steroid backbone. These data suggest that OB neurons are selectively excited by combinations of molecular features found on the side-chain and along the steroid nucleus of bile salt molecules.

Electrophysiological Evidence for a Chemotopy of Biologically Relevant Odors in the Olfactory Bulb of the Channel Catfish

2001 ◽  
Vol 86 (4) ◽  
pp. 1869-1876 ◽  
Author(s):  
Alexander A. Nikonov ◽  
John Caprio
Keyword(s):  
Amino Acids ◽  
Olfactory Bulb ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Bile Salts ◽  
Spatial Organization ◽  
Field Potential ◽  
Specific Class ◽  
Biologically Relevant ◽  
Excitatory Responses

Extracellular electrophysiological recordings from single olfactory bulb (OB) neurons in the channel catfish, Ictalurus punctatus, indicated that the OB is divided into different functional zones, each processing a specific class of biologically relevant odor. Different OB regions responded preferentially at slightly above threshold to either a mixture of 1) bile salts (10–7 to 10−5 M Na+ salts of taurocholic, lithocholic, and taurolithocholic acids), 2) nucleotides [10–6 to 10–4 M adenosine-5′-triphosphate (ATP), inosine-5′-monophosphate (IMP), and inosine-5′-triphosphate (ITP)], or 3) amino acids (10–6 to 10–4M l-alanine,l-methionine, l-arginine, andl-glutamate). Excitatory responses to bile salts were observed primarily in a thin, medial strip in both the dorsal (100–450 μm) and ventral (900–1,200 μm) OB. Excitatory responses to nucleotides were obtained primarily from dorsal, caudolateral OB, whereas excitatory responses to amino acids occurred more rostrally in the dorsolateral OB, but continued more medially in the ventral OB. The chemotopy within the channel catfish OB is more comparable to that previously described by optical imaging studies in zebrafish than by field potential studies in salmonids. The present results are consistent with recent studies, suggesting that the specific spatial organization of output neurons in the OB is necessary for the quality coding/decoding of olfactory information.

scholarly journals Electro-olfactogram and multiunit olfactory receptor responses to complex mixtures of amino acids in the channel catfish, Ictalurus punctatus.

1991 ◽  
Vol 98 (4) ◽  
pp. 699-721 ◽  
Author(s):  
J S Kang ◽  
J Caprio
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Binary Mixtures ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Olfactory Receptor ◽  
Complex Mixtures ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Receptor Sites

In vivo electrophysiological recordings from populations of olfactory receptor neurons in the channel catfish, Ictalurus punctatus, clearly showed that both electro-olfactogram and integrated neural responses of olfactory receptor cells to complex mixtures consisting of up to 10 different amino acids were predictable with knowledge of (a) the responses to the individual components in the mixture and (b) the relative independence of the respective receptor sites for the component stimuli. All amino acid stimuli used to form the various mixtures were initially adjusted in concentration to provide approximately equal response magnitudes. Olfactory receptor responses to both multimixtures and binary mixtures were recorded. Multimixtures were formed by mixing equal aliquots of 3-10 different amino acids. Binary mixtures were formed by mixing equal aliquots of two equally stimulatory solutions. Solution 1 contained either one to nine different neutral amino acids with long side-chains (LCNs) or one to five different neutral amino acids with short side-chains (SCNs). Solution 2, comprising the binary mixture, consisted of only a single stimulus, either a LCN, SCN, basic, or acidic amino acid. The increasing magnitude of the olfactory receptor responses to mixtures consisting of an increasing number of neutral amino acids indicated that multiple receptor site types with highly overlapping specificities exist to these compounds. For both binary mixtures and multimixtures composed of neutral and basic or neutral and acidic amino acids, the receptor responses were significantly enhanced compared with those mixtures consisting of an equal number of only neutral amino acids. These results demonstrate that receptor sites for the basic and acidic amino acids, respectively, are highly independent of those for the neutral amino acids, and suggest that a mechanism for synergism is the simultaneous activation of relatively independent receptor sites by the components in the mixture. In contrast, there was no evidence for the occurrence of mixture suppression.

Absorption of amino acids from intact dietary proteins and purified amino acid supplements follows different time-courses in channel catfish (Ictalurus punctatus)

Aquaculture ◽  
2009 ◽  
Vol 291 (3-4) ◽  
pp. 179-187 ◽  
Author(s):  
Amogh A. Ambardekar ◽  
Robert C. Reigh ◽  
Millie B. Williams
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Dietary Proteins ◽  
Time Courses

Responses of single facial taste fibers in the channel catfish, Ictalurus punctatus, to amino acids

1992 ◽  
Vol 68 (4) ◽  
pp. 1012-1026 ◽  
Author(s):  
J. Kohbara ◽  
W. Michel ◽  
J. Caprio
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Spontaneous Activity ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Response Times ◽  
Hierarchical Cluster ◽  
Whitney Test ◽  
Mann Whitney Test ◽  
Significant Difference

1. Amino acids and nucleotides stimulate taste receptors of teleosts. In this report, responses to these compounds of 105 facial taste fibers (79 fully characterized) that innervate maxillary barbel taste buds of the channel catfish (Ictalurus punctatus) were analyzed. 2. The fully characterized facial taste fibers that responded to amino acids (n = 68) were generally poorly responsive to nucleotides and related substances (NRS), whereas the fibers responsive to NRS (n = 11) were poorly responsive to amino acids. Spike discharge of the amino acid-responsive fibers to the most potent amino acid stimulus tested per fiber increased 44-fold from a mean spontaneous activity of 2.1 +/- 3.5 to 92.1 +/- 42.4 (SD) spikes/3 s. Spike activity of the NRS-responsive fibers to NRS increased 11.5-fold from a mean spontaneous activity of 3.4 +/- 5.9 to 39.1 +/- 27.4 spikes/3 s. There was no significant difference between the spontaneous rates, but stimulus evoked spike rates for the amino acid-responsive fibers were significantly greater (P < 0.05; Mann-Whitney test) than those for the NRS-responsive fibers. 3. Hierarchical cluster analysis based on the 3-s response time identified three major groups of neurons. The identified clusters comprised neurons that were highly responsive to either L-alanine (i.e., Ala cluster; n = 39), L-arginine (i.e., Arg cluster; n = 29), or NRS (NRS cluster; n = 11). Fibers comprising the Arg cluster were more narrowly tuned than those within the Ala cluster. This report further characterizes the responses to amino acids of the individual facial taste fibers comprising the Ala and Arg clusters. 4. Subclusters were evident within both of the amino acid-responsive clusters. The Arg cluster was divisible into two subclusters dependent on the response to 1 mM L-proline. Twelve neurons that were significantly (P < 0.05; Mann-Whitney test) more responsive to L-proline than the remaining 17 neurons within the Arg cluster formed the Arg/Pro subcluster; these latter 17 neurons comprised the Arg subcluster. However, there was no significant difference (Mann-Whitney test) in the response to L-arginine between fibers within either subcluster across four different response times analyzed. Fibers within the Ala cluster were generally poorly responsive to L-proline. Four alanine subclusters were suggested on the basis of their relative responses to L-alanine, D-alanine, L-arginine, and the NRS; however, of the 39 fibers comprising the alanine cluster, two alanine subclusters comprised only two fibers each, and the third subcluster consisted of four fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

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