Workshop overview. Identification of respiratory allergens

A variety of chemicals and proteins can sensitize the respiratory tract. Among these are materials of industrial importance, including certain diisocyanates, acid anhydrides, reactive dyes, and enzymes. Currently, no widely accepted or well-validated methods for the prospective identification of respiratory allergens exist. Most progress has been made with guinea pig methods where sensitizing potential is measured usually by assessment of changes in pulmonary function induced following sensitization and challenge. However, these methods are often prohibitively expensive, particularly for screening purposes. A number of alternative approaches are under consideration and are described here. The nature of the health problems associated with occupational respiratory sensitization, chemical structure-activity analyses as a tool for detecting pulmonary allergens, approaches used to test for respiratory allergens in guinea pigs, and alternative approaches using mice are all discussed. Finally, regulatory issues and needs with respect to respiratory sensitization are outlined.

Taste aversion learning in fyn mutant mice

Conditioned taste aversion (CTA) learning is a robust form of classical conditioning in which animals rapidly associate a flavor with aversive internal symptoms. The present study assessed CTA learning in transgenic mice deficient in a specific nonreceptor tyrosine kinase (the fyn mutant). Fyn mutants show impaired long-term potentiation and marked deficits in acquisition of spatial learning tasks. To assess whether they are also impaired in CTA learning, fyn mutant and wild-type mice received 2 conditioning trials consisting of access to a flavored solution followed by administration of LiCl. Fyn mutant mice acquired significant CTAs following a single conditioning trial and these aversions were comparable to those seen in wild-type mice. These results indicate that the fyn mutation does not interfere with the acquisition of CTAs and hence that this mutation is not associated with a global learning deficit.

A placebo-controlled multicenter study of auranofin in the treatment of patients with corticosteroid-dependent asthma. Auranofin Multicenter Drug Trial

BACKGROUND

Previous clinical studies have demonstrated that injectable gold salts and the oral gold compound, auranofin, possess significant steroid-sparing effects in the treatment of asthma.

OBJECTIVES

The objectives of this investigation were to determine whether auranofin could reduce oral corticosteroid requirements and to evaluate the safety of auranofin in the treatment of chronic corticosteroid-dependent asthma.

METHODS

Patients with asthma were eligible if they required at least 10 mg of prednisone per day for control and prevention of asthma exacerbations. Two hundred seventy-nine patients with chronic corticosteroid-dependent asthma (requiring > or = 10 mg/day) were randomized to receive auranofin, 3 mg twice daily, or placebo during an 8-month clinical trial, which was divided into three phases including: a 4-week baseline period (phase I), a 6-month double-blind treatment and steroid reduction period (phase II), and a 4-week posttreatment observation period during which steroid and auranofin doses or placebo doses were maintained at levels achieved by the end of phase II (phase III). The primary efficacy variable was "therapeutic success" or reduction of daily corticosteroid use by 50% or more.

RESULTS

The proportion of patients in the auranofin group achieving therapeutic success (41%) was significantly higher than that in the placebo group (27%) (p = 0.01). This effect was greatest in patients requiring 10 to 19 mg of oral prednisone per day at baseline (p < 0.001). In all treated patients, including those who did and did not complete the trial, significant reduction (> or = 50% of baseline) in oral corticosteroid dosage was achieved in the auranofin group (60%) compared with the placebo group (32%) (p < 0.001). There were no significant differences between treatment groups in symptoms, concomitant medication use, or lung function. Mean serum total IgE levels decreased significantly from baseline in the auranofin group (-44.63 IU/ml) compared with the placebo group (p = 0.001). Gastrointestinal and cutaneous adverse events were greater in the auranofin group.

CONCLUSIONS

Auranofin demonstrated a steroid-sparing effect without concomitant worsening of symptoms or lung function and appeared to be more effective in patients dependent on 10 to 19 mg of prednisone per day. Therefore this study has demonstrated that auranofin is useful as a steroid-sparing agent in the treatment of chronic corticosteroid-dependent asthma.

Sodium appetite in the sham-drinking rat after chorda tympani nerve transection

Sodium depletion in the neurologically intact rat (Intact) produces a prompt and robust intake of NaCl. After chorda tympani nerve transection (CTX), there is a longer latency and a reduced intake of NaCl. The CTX rat depends on remaining gustatory and postingestive information to direct NaCl intake. In the present study, the effect of the removal of the postingestive signals of ingested NaCl (by means of a chronic gastric fistula) on the NaCl intakes and licking patterns of Intact and CTX rats was studied. When the gastric fistula was open (Sham), ingested NaCl did not pass beyond the stomach, thus negative postingestive stimulation was absent. After overnight sodium depletion, when postingestive stimulation was present (i.e., gastric fistula closed; Real), the CTX group drank significantly less 0.3 M NaCl than the Intact group over the 2-h test [11.7 +/- 1.6 (CTX) vs. 15.3 +/- 2.8 (Intact) ml]. In contrast, when postingestive signals were absent (i.e., Sham) the Intact group ingested 52.5 +/- 4.4 ml, whereas the CTX group had ingested only 12.4 +/- 3.1 ml of 0.3 M NaCl. Lickometer data analysis revealed that even during the first minute of the test the CTX/Real group generated significantly fewer licks than any of the other groups. Thus, although the CTX group was sensitive to inhibitory postingestive signals in the early portion of the appetite test, the absence of these signals did not release the robust and sustained intake of NaCl characteristic of the Intact group. These results suggest that information provided by the chorda tympani nerve is critically important to the strong motivational properties of NaCl after sodium depletion.

Retention of conditioned taste aversion to NaCl after chorda tympani transection in Fischer 344 and Wistar rats

Fischer 344 (F344) rats fail to prefer sodium chloride (NaCl) solution to water, and this behavior is dramatically altered by bilateral transection of the chorda tympani nerve (CTX). Tests of retention and generalization of a conditioned taste aversion (CTA) to 0.15 M NaCl were used to assess alterations in salt taste perception after CTX. A CTA was established to 0.15 M NaCl in groups of F344 and Wistar rats after two pairings with LiCl (IP, 2% body weight; 0.15 M). After conditioning, animals received bilateral CTX or sham operations. Approximately 2 weeks after surgery animals were tested for retention of the CTA. Aversion to 0.15 M NaCl was evident in CTX and SHAM rats that had been conditioned prior to surgery, with no apparent difference in magnitude as a function of surgical condition. Thus, although CTX profoundly alters F344 rats' hedonic response to NaCl, it does not alter perceptual characteristics so markedly that NaCl is no longer recognized as the stimulus presented during aversion conditioning. Rather these studies suggest that in both the F344 and Wistar strains the chorda tympani nerve is not necessary for retention of a presurgical CTA to NaCl. These studies, therefore, do not provide evidence of changes in NaCl perceptual "quality" as a consequence of CTX either in F344 rats, where such changes were indicated by the preference data, or in the Wistar rat, where they were not.

Neonatal chorda tympani transection alters adult preference for ammonium chloride in the rat

The immature gustatory system of the neonatal rat is characterized by sensitivity to disruption by early interventions such as receptor or nerve damage. The present studies examined the effect of chorda tympani transection (neoCTX) of neonates on adult preference for salt and nonsalt stimuli. NeoCTX at 10 days of age led to a striking change in adult rats' preference for NH4Cl solutions but little change in preference for other solutions, including NaCl and KCl. Permanent anatomical effects of neoCTX included failure of the nerve to regenerate and a loss of all fungiform taste buds. Preference for NH4Cl was not due to an inability to discriminate it from NaCl. Following taste aversion conditioning to NaCl, neoCTX rats clearly distinguished between NaCl and NH4Cl. The effects on NH4Cl preference reflect a sensitive period during development because adult rats receiving similar surgery did not show any change in NH4Cl preference.

Neutral mediation of food aversions and anorexia induced by tumor necrosis factor and tumors

Tumors often cause declines in food intake and body weight, a condition referred to as tumor anorexia. A macrophage-derived peptide known as tumor necrosis factor (TNF) has been proposed as an important mediator of cancer anorexia and cachexia. Our work with an animal model of this condition indicates that strong learned aversions to the available diet arise in rats bearing implanted tumors and that these aversions contribute significantly to depressions in food intake and body weight. Lesions of the area postrema and nearby caudal medial nucleus of the solitary tract (APcmNTS) markedly attenuate both the learned aversions and the anorexia induced by tumor growth. A strikingly similar pattern of effects on tumor-induced aversions and anorexia was seen after subdiaphragmatic vagotomy and after capsaicin treatments. The similarity in the effects of all three treatments suggest that they involve interruption of the same system, presumably afferent signals conveyed by the vagus nerve to the nucleus of the solitary tract. The extent to which peripheral TNF administration generates symptoms similar to those produced by tumor growth was also examined. TNF administration was associated with the development of strong aversions to a novel but not a familiar diet. Area postrema lesions were found to significantly attenuate the effects of TNF on novel diet intake and preference. These observations provide parallels between the effects of TNF and the effects of tumor growth on diet aversions and food intake.

Morning sickness: impact on offspring salt preference

These studies examined the relationship between salt preference of adult offspring and their mothers' symptoms of morning sickness during pregnancy. College students who could provide information about their mothers' symptoms of morning sickness completed a survey about their dietary salt intake (study 1; n = 169) or rated and consumed ten snack foods (study 2; n = 66). In study 1 a salt-use score was calculated based on responses to the Salt Intake Questionnaire; offspring of women with moderate or severe vomiting reported a significantly higher level of salt use (p < 0.01) than those whose mothers report little or no symptoms. In study 2 saltiness and pleasantness ratings of high-salt foods, intake of those foods and total sodium intake were the focus of analysis. Offspring of women reporting moderate or severe vomiting showed a significantly greater preference for the snack food subjects rated as saltiest than those whose mothers reported no or mild vomiting. They also ate more of that food and consumed more total sodium during the test session. Effects were stronger in Caucasian than Asian subjects. These studies suggest that moderate to severe vomiting during pregnancy can be associated with significantly higher salt intake in offspring. Thus, a gestational event may be an important determinant of salt intake and preference in adulthood.

Forebrain contribution to the induction of a cellular correlate of conditioned taste aversion in the nucleus of the solitary tract

A conditioned taste aversion (CTA) is a form of classical conditioning in which animals avoid a taste (conditioned stimulus; CS) which has been previously paired with a treatment (unconditioned stimulus; US) that produces transient illness. Recently, a reliable cellular correlate of the behavioral expression of a CTA was identified using c-Fos immunostaining as a marker of neuronal activation. Exposure to a saccharin solution (CS) which had previously been paired with lithium chloride (LiCl; US) induced significant c-Fos-like immunoreactivity (c-FLI) in the intermediate zone of the nucleus of the solitary tract (NTS), a response that was quite similar to that displayed following administration of LiCl alone. The present studies employed a variant of the chronic decerebrate rat preparation to explore whether circuitry intrinsic to the brainstem is sufficient for the induction of c-FLI in both as an unconditioned response to the LiCl and as a conditioned response to the saccharin. Using chronic hemidecerebrate rats, which have a unilateral brain transection at the level of the superior colliculus, we found that the unconditioned c-FLI to LiCI was unaltered by the transection, while the conditioned expression of c-FLI to the CS taste was evident only on the side of the NTS which retained neural connections with the forebrain. These findings strongly implicate forebrain input in this cellular correlate of CTA learning and also indicate that the pathways mediating the response to the US (LiCl) and the CS (saccharin) differ.

Machine operator's lung. A hypersensitivity pneumonitis disorder associated with exposure to metalworking fluid aerosols

Six auto parts manufacturing workers were referred for evaluation of a 6-week history of work-related dyspnea, cough, and fatigue. Two workers also reported fever and weight loss. All six worked in a machining area where a waterbased metalworking fluid was used and recirculated under high pressure, thereby creating an aerosol. Chest radiographs revealed pulmonary interstitial infiltrates in four workers. Lung function tests showed that four workers had decreased diffusing capacity. After removal from the work area, all workers recovered. The metalworking fluid was cultured for bacteria and fungi. Isolates from broth cultures were sonicated to obtain antigen extracts. Serum precipitins to one or more of the microbial isolates were identified in all six workers but not in eight of nine nonexposed control subjects. The most frequent precipitin response (six of six workers) was against antigens of Pseudomonas fluorescens, which was cultured from the metalworking fluid. In all workers, precipitins to at least one other cultured organism were detected; these included Aspergillus niger, Staphylococcus capitas, an acid-fast Rhodococcus sp, and Bacillus pumilus. This represents the first report of hypersensitivity pneumonitis associated with industrial exposure to aerosolized metalworking fluid. Observed precipitin responses to a variety of microbial contaminants in metalworking fluid strongly suggest a causative role for microbial antigens in the induction and elicitation of this manifestation of hypersensitivity pneumonitis.

The CS-US interval and taste aversion learning: a brief look

Temporal parameters of taste aversion learning are known to differ markedly from other learning paradigms in that acquisition occurs despite lengthy delays between exposure to conditioned (CS) and unconditioned stimulus (US). Far less consideration has been paid to very brief CS-US intervals and the possibility that this learning may also be distinguished by an ineffectiveness of close temporal contiguity between CS and US. The effectiveness of a very brief CS-US interval (10 s) was compared with that of 2 lengthier intervals (15 and 30 min). Temporal control of CS delivery (0.15% saccharin solution) into the oral cavity and US delivery (7.5 mg/kg apomorphine hydrochloride) into circulation involved infusion pumps and indwelling catheters. Using a 1-trial learning paradigm, CS-US delays of 15 and 30 min led to significant aversions whereas the 10-s CS-US interval did not, suggesting that close temporal contiguity between CS and US is neither necessary nor sufficient for conditioned taste aversion acquisition.

c-Fos induction in response to taste stimuli previously paired with amphetamine or LiCl during taste aversion learning

Amphetamine and lithium chloride (LiCl) are both effective unconditioned stimuli (USs) in the establishment of conditioned taste aversions (CTA) in the rat. However, the mechanism of action of these drugs is quite different with the area postrema and related emetic circuitry critical to the response to LiCl but not amphetamine. c-Fos immunohistochemistry was used to define brain regions activated during drug administration and during expression of a CTA using either amphetamine or LiCl as the US drug. Administration of LiCl induced dense c-Fos-like immunoreactivity (c-FLI) in the nucleus of the solitary tract (NTS) while amphetamine induced only light staining in this area. A conditioned stimulus (CS) saccharin solution paired with amphetamine, however, was associated with c-FLI in NTS in a pattern quite similar to that seen to a LiCl-paired CS. This suggests that the pattern of c-Fos expression to a taste CS after conditioning is characteristic of aversion conditioning, in general, and appears not to represent a matching of the conditioned response to specific unconditioned effects of the drug. To examine this conditioned response further, c-FLI to the aversive saccharin CS was compared to the response to quinine hydrochloride, which is innately aversive. Although behaviorally the animals' ingestive responses were quite similar, the saccharin CS induced significant elevations of c-FLI in NTS whereas the quinine did not. Thus, a taste which had become aversive by virtue of conditioning induced c-FLI expression in NTS while a taste which was inherently aversive did not.

A self-management program for adult asthma. Part II: Cost-benefit analysis

BACKGROUND

We performed a cost-benefit analysis of a previously described self-management program for adult asthma.

METHODS

Direct and indirect cost data from 47 subjects who participated in the self-management program were analyzed. In particular, costs incurred by the subjects 1 year before participation were compared with costs incurred 1 year after participation.

RESULTS

The cost-benefit analysis indicated that the program was beneficial, reducing the cost of asthma to each patient by $475.29. The benefit came primarily from reductions in hospital admissions (reduced from $18,488 to $1538) and income lost as a result of asthma (reduced from $11,593 to $4589). The asthma self-management program cost $208.33 per patient. Comparison of the program cost with the program benefit produced a 1:2.28 cost-benefit ratio, demonstrating that the program more than paid for itself.

CONCLUSION

A self-management program for adult asthma effectively reduced the cost associated with asthma. The findings are especially salient because the subjects' asthma was generally under good medical control when they participated in the program. The savings were therefore not the result of improved medical treatment; medical treatment was a controlled parameter, not a variable, in the self-management study. The self-management program for adult asthma was cost-beneficial.

Amiloride sensitivity in the neonatal rat

Amiloride-sensitive sodium channels in taste buds appear to play a key role in the response to NaCl stimulation, at least in adult rats. The researchers examined whether neonatal rats, which display an exaggerated preference for hypertonic NaCl solutions, lack functional amiloride-sensitive sodium channels. NaCl intake was significantly reduced by amiloride pretreatment, but water and ammonium chloride, NH4Cl, were unaffected. The researchers assessed whether the early appearance of amiloride sensitivity was mediated by effects on chorda tympani (CT) activity by sectioning the CT before testing. CT transection reduced intake of NaCl solutions and eliminated evidence of amiloride sensitivity. Amiloride sensitivity was also assessed by recording of whole-nerve CT activity at 8-11 days of age; the response to NaCl stimulation was significantly suppressed by amiloride. These data indicate that amiloride-sensitive sodium channels develop earlier than previously believed.

A self-management program for adult asthma. Part I: Development and evaluation

BACKGROUND

We developed and evaluated a self-management program for adult asthma. In developing the program, we considered questions of format and behavior control. The format we selected included components known to be effective in educational settings. We regulated asthma management behavior through the introduction of environmental cues.

METHODS

Seventy-six subjects, whose asthma was generally under medical control, were assigned randomly to either a treatment group or a waiting-list control group. Those in the treatment group were exposed to a 7-week program that incorporated proven features of providing effective training and establishing behavioral control. Subsequently, subjects in the control group received the treatment. Short-term evaluation of the treatment was made after the subjects in the experimental group were trained but before the control subjects were trained. Long-term evaluation was conducted after both groups of subjects were trained.

RESULTS

Over the short term, self-management training led to fewer asthma symptoms and physician visits and improvement in asthma management skills and cognitive abilities. Over the long term, self-management training was related to lower asthma attack frequency, reduced medication use, improvement in cognitive measures, and increased use of self-management skills.

CONCLUSIONS

The program improved asthma management in patients whose conditions were already under good medical control. The effects of the program were apparent a year after the conclusion of self-management training.

Rapid venom immunotherapy is safe for routine use in the treatment of patients with Hymenoptera anaphylaxis

BACKGROUND

Rapid venom immunotherapy regimens have been developed to provide safe protection to individuals who have experienced Hymenoptera anaphylaxis by administering greater than 50 micrograms of venom over two to three hours on treatment day 1. A rapid venom immunotherapy protocol which consisted of administration of a cumulative dose of 58.55 micrograms of each venom on treatment day 1 followed by an accelerated build-up over 3 weeks to a final maintenance dose of 100 micrograms per venom was developed by our group in 1984.

OBJECTIVE

We report our 10-year cumulative experience with this rapid venom immunotherapy regimen.

METHODS

Seventy-seven venom-allergic patients received a cumulative dose of 58.55 micrograms per venom on treatment day 1 in an ambulatory care setting. Rapid venom immunotherapy was assessed for safety. A cost analysis was performed to compare rapid venom immunotherapy to a modified rush immunotherapy regimen.

RESULTS

Four patients (5.2%), experienced mild systemic reactions consisting of diffuse urticaria on day 1. Treatment was otherwise well tolerated. Resting events occurred in 21 patients, a mean number of 12 months (range: 3 days to 48 months) after treatment, without systemic reactions.

CONCLUSIONS

This experience confirms that rapid venom immunotherapy is safe to administer in an ambulatory setting and should be considered especially for patients during the stinging insect season when rapid protection is required.

Amiloride sensitivity in the neonatal rat

Amiloride-sensitive sodium channels in taste buds appear to play a key role in the response to NaCl stimulation, at least in adult rats. The researchers examined whether neonatal rats, which display an exaggerated preference for hypertonic NaCl solutions, lack functional amiloride-sensitive sodium channels. NaCl intake was significantly reduced by amiloride pretreatment, but water and ammonium chloride, NH4Cl, were unaffected. The researchers assessed whether the early appearance of amiloride sensitivity was mediated by effects on chorda tympani (CT) activity by sectioning the CT before testing. CT transection reduced intake of NaCl solutions and eliminated evidence of amiloride sensitivity. Amiloride sensitivity was also assessed by recording of whole-nerve CT activity at 8-11 days of age; the response to NaCl stimulation was significantly suppressed by amiloride. These data indicate that amiloride-sensitive sodium channels develop earlier than previously believed.

Characterization of skin prick testing responses for detecting sensitization to detergent enzymes at extreme dilutions: inability of the RAST to detect lightly sensitized individuals

We observed that a group of detergent enzyme workers with known exposure to the subtilisin enzyme, Alcalase (Novo Industries, Bagsvaerde, Denmark), exhibited percutaneous sensitivity to Savinase (Novo Industries), a microbial protease, to which there was no previous occupational exposure. This was attributed to either cross-reactivity between these enzymes or to foreign enzyme contaminants contained in the Savinase antigen. The aims of this study were to determine the range of concentrations eliciting percutaneous responses to Alcalase and to another enzyme, Rapidase (an alpha-amylase) (Gist Brocades, Belgie, Netherlands); to compare the sensitivity of RAST and skin prick testing; and to characterize the relationship between wheal size and antigen concentration. Prick testing was conducted over six log10 antigen dilutions of Alcalase and Rapidase in 30 workers with previous exposure and skin reactivity to enzymes (group 1) and compared to nonexposed control groups, which included 60 atopic subjects (group 2) and 30 nonatopic subjects (group 3). The RAST was performed with Alcalase and Rapidase antigens. The percutaneous threshold concentrations in group 1 subjects varied widely from 10(3) to 10(-3) micrograms of protein per milliliter. Of 19 group 1 workers with skin test reactivity to Alcalase, 84% had positive RAST results; 83% of 24 workers who were reactive to Rapidase had positive RAST results. It was concluded that skin prick testing is preferred over in vitro methods for longitudinal monitoring of human sensitization to workplace allergens. In addition, the data predicted that based on a known Alcalase level of 0.07% in Savinase, 26% of Alcalase-sensitized subjects could react to Savinase. An excellent correlation (r > 0.97) was found between log concentration of antigen and wheal size parameters, with the log diameter and log area performing equally as well (r > 0.98). Analysis of variance revealed that more than 60% of intragroup variation represented human variability in wheal parameters at each concentration tested, whereas at least 95% of intergroup variation was due to regression. The excellent correlations of both wheal diameter and area with antigen concentrations were attributed to the very small changes observed between test concentrations.

A combined respiratory and cutaneous hypersensitivity syndrome induced by work exposure to quaternary amines

The quaternary amine, benzalkonium chloride, has been associated with cutaneous and mucosal delayed hypersensitivity reactions and with paradoxical bronchoconstriction after use of aerosolized asthma medications. Until now, quaternary amines have not been reported to cause occupational asthma. We describe a case of occupational asthma caused by prolonged exposure to a cleaning solution containing benzalkonium chloride in the workplace. Single-blind, placebo-controlled, open-room challenges were performed to determine the specific agent responsible for the patient's symptoms. Pulmonary function and epicutaneous challenge tests were also performed. The patient had positive responses to challenges with a liquid toilet bowl cleaner containing benzalkonium chloride but was unreactive to other agents tested. Removal from the workplace resulted in complete resolution of symptoms. The exact mechanisms responsible for occupational asthma induced by quaternary amines remain unknown; however, this case emphasizes the importance of recognizing reactive chemicals as possible causes.

c-Fos induction in response to a conditioned stimulus after single trial taste aversion learning

Taste aversion conditioning is characterized by its prompt acquisition despite the introduction of long delays between CS (taste) and UCS (toxic drug). Although the dramatic changes in behavioral response to a taste after this conditioning are well documented, relatively little is known about the changes in neural activity that accompany this learning. c-Fos immunohistochemical staining was employed to define brain regions activated during the expression of a conditioned taste aversion (CTA). The present studies examined c-Fos immunoreactivity in the brains of rats after i.p. injection of LiCl or NaCl or after intraoral infusion of a saccharin CS. LiCl administration, a common unconditioned stimulus (UCS) in CTA experiments, was found to induce c-Fos protein in a number of brainstem regions, including the nucleus of the solitary tract (NTS), medial and lateral pontine parabrachial nucleus (PBN), and hypoglossal nucleus. Conditioned animals received a single pairing of the CS saccharin with the UCS LiCl, while controls were exposed to the CS saccharin but received non-contingent LiCl 24 h after saccharin exposure. Following saccharin re-exposure, conditioned animals showed patterns of neuronal activation to a taste which were similar to those activated by the UCS drug. Specifically, the pattern of c-Fos expression in conditioned animals was confined to the same region of the NTS which showed the most activation following the UCS LiCl. This pattern of activation was not evident in controls re-exposed to saccharin.(ABSTRACT TRUNCATED AT 250 WORDS)

Gustatory deafferentation and desalivation: effects on NaCl preference of Fischer 344 rats

The chorda tympani nerve (CT) appears to be particularly responsive to NaCl stimulation of the tongue. However, in most strains of rat, bilateral transection of the CT (CTX) results in little alteration of salt preference. The Fischer 344 (F344) strain of rat is unusual in its lack of preference for any concentration of salt. We recently reported a dramatic change from aversion to preference for salt in F344 rats after CTX. The present studies further explored this alteration in salt preference of F344 rats with an expanded range of NaCl concentrations. Additionally, the specificity of the CT in mediating F344 salt aversion was examined by testing NaCl preference after glossopharyngeal nerve (GL) transections, combined CT and GL deafferentation, and partial desalivation. Comparison with Wistar rats revealed that salt preference of F344 CTX rats followed a typical preference/aversion pattern across a range of NaCl concentrations. Studies of GL section, either alone or combined with CT sectioning, indicated that F344 rats' aversion was dependent on the integrity of the CT and not the GL. Removal of sublingual and submaxillary salivary glands did not lead to preference changes similar to those after CTX, indicating that the effects of CTX are not secondary to desalivation. Overall, the findings point to signals from the CT as playing a primary role in the NaCl aversion displayed by the intact F344 rat.