A novel method for measurements of sleep/wake states, feeding and drinking behaviors using the tracking technique of 3D positions in freely moving mice.

We have previously developed a 3D video tracking system which enables us to analyze long-term quantitative analysis of gene expression in freely moving mice. In the present study, we improved 3D video tracking and developed a system that analyzes more detailed behavioral data. We succeeded in simultaneously analyzing sleep-wake, feeding, and drinking behavior rhythms in the same individual using our tracking system. This system will make it possible to measure gene expression in each tissue in vivo in real time in relation to the various behavioral rhythms mentioned above.

High-Precision Optical Fiber-Based Lickometer.

Quantifying and analyzing licking behavior can offer valuable insights into fundamental neurobiological mechanisms controlling animal consummatory behaviors. Lickometers are typically based on electrical properties, a strategy that comes with limitations, including susceptibility to electrical interference and generation of electrical disturbances in electrophysiological measurements. While optical lickometers offer an alternative method to measure licks and quantify fluid intake in animals, they are prone to false readings and susceptibility to outside light sources. To overcome this problem, we propose a low-cost open-source lickometer that combines a restricted infrared beam defined by optical fibers, with a poke design that allows easy access to the tongue while limiting access of other body parts and external light sources. This device also includes features for detecting nose pokes and presenting visual cues during behavioral tasks. We provide validation experiments that demonstrate the optical lickometer's reliability, high-sensitivity and precision, and its application in a behavioral task, showcasing the potential of this tool to study lick microstructure in combination with other techniques, such as imaging of neural activity, in freely moving mice.

High-throughput low-cost digital lickometer system for the assessment of licking behaviours in mice.

BACKGROUND: Proper hydration is essential for maintaining health and supports various biological processes, including temperature regulation, immune function, nutrient delivery, and organ function. Visual assessment has traditionally been used to quantify liquid intake, although technological advances in optical and electrical sensors now offer higher accuracy and larger potential for automatic operation with millisecond precision and individual lick resolution. NEW METHOD: We describe an inexpensive electronic sensor board to monitor mouse licking behavior. The system is equipped with integrated filtering and data preprocessing steps. It measures lick count, frequency, width and interlick intervals with high resolution, allowing the real-time monitoring of complex licking patterns in several mice in their respective home cages over prolonged periods. RESULTS: Our lickometer provides two-millisecond resolution, efficiently detecting variations in licking behaviors in mice. The system is adapted to monitor licking behaviors in up to 12 mice simultaneously. Lick count, duration and interlick intervals, along with preference for sweet water were monitored over two days, revealing variations in licking patterns across light and dark phases extended over prolonged periods. COMPARISON WITH EXISTING METHODS: Our lickometer allows for monitoring licking behaviors and dynamics. It can be adapted to conventional mouse cages using electrical circuits. It is open-source, cost-effective, efficient, and can be utilized in real-time for large cohorts, representing an ideal tool for studying ingestive dynamics in different environmental and pathological contexts. CONCLUSION: We have developed a novel, cost-effective, and efficient device to monitor ingestive behaviors in mice. The throughput of our device allows for monitoring several mice simultaneously while it can be applied directly to a conventional mouse cage, simplifying its implementation into pre-existing experimental setups.

Control of fluid intake in dehydrated rats and evolution of sodium appetite.

The objective of the present work is to examine from a new perspective the existence of causal factors not predicted by the classical theory that thirst and sodium appetite are two distinct motivations. For example, we ask why water deprivation induces sodium appetite, thirst is not "water appetite", and intracellular dehydration potentially causes sodium appetite. Contrary to the classical theory, we suggest that thirst first, and sodium appetite second, designate a temporal sequence underlying the same motivation. The single motivation becomes an "intervenient variable" a concept borrowed from the literature, fully explained in the text, between causes of dehydration (extracellular, intracellular, or both together), and respective behavioral responses subserved by hindbrain-dependent inhibition (e.g., lateral parabrachial nucleus) and forebrain facilitation (e.g., angiotensin II). A corollary is homology between rat sodium appetite and marine teleost thirst-like motivation that we name "protodipsia". The homology argument rests on similarities between behavior (salty water intake) and respective neuroanatomical as well as functional mechanisms. Tetrapod origin in a marine environment provides additional support for the homology. The single motivation hypothesis is also consistent with ingestive behaviors in nature given similarities (e.g., thirst producing brackish water intake) between the behavior of the laboratory rat and wild animals, rodents included. The hypotheses of single motivation and homology might explain why hyperosmotic rats, or eventually any other hyperosmotic tetrapod, shows paradoxical signs of sodium appetite. They might also explain how ingestive behaviors determined by dehydration and subserved by hindbrain inhibitory mechanisms contributed to tetrapod transition from sea to land.

Modeling the effect of ambient temperature on reticulorumen temperature, and drinking and eating behaviors of late-lactation dairy cows during colder seasons.

Dairy cows may suffer thermal stress during the colder seasons especially due to their open-air housing systems. Free water temperature (FWT) and feed temperature (FT) are dependent on ambient temperature (AT) and can be critical for maintaining body and reticulorumen temperature (RT) in cold conditions. The objective of this study was to determine the effects of FWT and FT on RT fluctuations, and of AT on RT and drinking and eating behaviors in late-lactation cows during cold exposure. Data were collected from 16 multiparous lactating cows for four 6-d periods during the autumn and winter seasons. The cows (224 ± 36 days in milk; mean ± SD) had an average milk yield (MY) of 24.8 ± 4.97 kg/d and RT of 38.84 ± 0.163 °C. Daily average AT ranged from 4.38 to 17.25 °C. The effects of the temperature and amount of the ingested water or feed on RT change and recovery time, and the effect of the daily AT on RT, feed and water intake, and drinking, eating, and rumination behaviors were analyzed using the generalized additive mixed model framework. Reticulorumen temperature change and recovery time were affected by FWT (+0.0596 °C/°C and -1.27 min/°C, respectively), but not by FT. The amount of the ingested free water and feed affected RT change (-0.108 °C/kg drink size and -0.150 °C/kg meal size, respectively), and RT recovery time (+2.13 min/kg drink size and + 3.71 min/kg meal size, respectively). Colder AT decreased RT by 0.0151 °C/°C between 9.91 and 17.25 °C AT. Cows increased DM intake (DMI) by 0.365 kg/d per 1 °C drop in AT below 10.63 °C, but with no increase in MY. In fact, MY:DMI decreased by 0.0106/°C as AT dropped from 17.25 to 4.38 °C. Free water intake (FWI) was reduced by 0.0856 FWI:DMI/°C as AT decreased from 17.25 to 8.27 °C. Cold exposure influenced animal behavior with fewer drink and meal bouts (-0.432 and -0.290 bouts/d, respectively), larger drink sizes (+0.100 kg/bout), and shorter rumination time (-5.31 min/d) per 1 °C decrease in AT from 17.25 °C to 8.77, 12.53, 4.38, and 10.32 °C, respectively. In conclusion, exposure to low AT increased feed intake, reduced water intake, and changes in eating, drinking and rumination behaviors of dairy cows in late lactation. Additionally, the consequences of cold exposure on cows may be aggravated by ingestion of feed and free water at temperatures lower than the body, potentially impacting feed efficiency due to the extra energetic cost of thermoregulation.

Seasonality Affects Fluid Intake Behaviors among Young Adults in Hebei, China.

BACKGROUND: Evidence on the association between environmental factors and fluid intake behavior remains limited. The current study aims to explore seasonal variations in fluid intake behaviors among young adults in China. METHODS: A prospective cohort of 79 healthy young adults (43 males and 36 females) aged 19-21 in Hebei, China, was assessed for fluid intake behaviors for four seasons. For each assessment, the participants' anthropometric measurements were collected. Temperature and humidity on survey days were measured. Participants' total drinking fluid (TDF) was recorded using a self-administrative 7 d, 24 h fluid intake questionnaire. To calculate water from food (WFF), we weighed all foods consumed by participants. Duplicates of consumed food samples were collected to measure the water content via the drying method. RESULTS: The mean total water intake (TWI) was 2761 ± 881, 2551 ± 845, 2210 ± 551, and 1989 ± 579 for spring, summer, fall, and winter, respectively (F(2.37) = 42.29, p < 0.001). The volume and proportion of TWI from TDF and WFF varied across the four seasons. The volume of WFF in spring (1361 ± 281, F(2.61) = 17.21, p < 0.001) and TDF in summer (1218 ± 502, F(2.62) = 9.36, p < 0.001) was among the highest, while participants' fluid intake behaviors in spring and summer were less distinct than the other pairwise comparisons. A moderate association was found between outdoor temperature and TDF (r = 0.53, p < 0.01). Different general estimating equations suggested that gender, seasonality, outdoor temperature, differences in indoor and outdoor temperature, and mean temperature were independent factors of TDF. An interactive effect was found for gender and temperature, showing that the expected TDF of males may increase more as the temperature climbs. CONCLUSIONS: Gender, seasonality, and air temperature could significantly affect fluid intake behaviors, including the amount and type of fluid intake. However, the independent effect of BMI and humidity remains unclear.

Using structured problem solving to promote fluid consumption in the prevention of urinary stones with hydration (PUSH) trial.

BACKGROUND: Structured Problem Solving (SPS) is a patient-centered approach to promoting behavior change that relies on productive collaboration between coaches and participants and reinforces participant autonomy. We aimed to describe the design, implementation, and assessment of SPS in the multicenter Prevention of Urinary Stones with Hydration (PUSH) randomized trial. METHODS: In the PUSH trial, individuals with a history of urinary stone disease and low urine output were randomized to control versus a multicomponent intervention including SPS that was designed to promote fluid consumption and thereby prevent recurrent stones. We provide details specifically about training and fidelity assessment of the SPS coaches. We report on implementation experiences related to SPS during the initial conduct of the trial. RESULTS: With training and fidelity assessment, coaches in the PUSH trial applied SPS to help participants overcome barriers to fluid consumption. In some cases, coaches faced implementation barriers such as variable participant engagement that required tailoring their work with specific participants. The coaches also faced challenges including balancing rapport with problem solving, and role clarity for the coaches. CONCLUSIONS: We adapted SPS to the setting of kidney stone prevention and overcame challenges in implementation, such as variable patient engagement. Tools from the PUSH trial may be useful to apply to other health behavior change settings in nephrology and other areas of clinical care. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT03244189.

Dopamine, activation of ingestion and evaluation of response efficacy: a focus on the within-session time-course of licking burst number.

RATIONALE: Evidence on the effect of dopamine D1-like and D2-like receptor antagonists on licking microstructure and the forced swimming response led us to suggest that (i) dopamine on D1-like receptors plays a role in activating reward-directed responses and (ii) the level of response activation is reboosted based on a process of evaluation of response efficacy requiring dopamine on D2-like receptors. A main piece of evidence in support of this hypothesis is the observation that the dopamine D2-like receptor antagonist raclopride induces a within-session decrement of burst number occurring after the contact with the reward. The few published studies with a detailed analysis of the time-course of this measure were conducted in our laboratory. OBJECTIVES: The aim of this review is to recapitulate and discuss the evidence in support of the analysis of the within-session burst number as a behavioural substrate for the study of the mechanisms governing ingestion, behavioural activation and the related evaluation processes, and its relevance in the analysis of drug effects on ingestion. CONCLUSIONS: The evidence gathered so far suggests that the analysis of the within-session time-course of burst number provides an important behavioural substrate for the study of the mechanisms governing ingestion, behavioural activation and the related evaluation processes, and might provide decisive evidence in the analysis of the effects of drugs on ingestion. However, further evidence from independent sources is necessary to validate the use and the proposed interpretation of this measure.

Drinking behavior patterns may be associated with persistent depressive symptoms after alcohol abstinence in alcohol use disorder.

AIM: This study examined the association between drinking behavior patterns and depressive symptoms after alcohol abstinence in patients with alcohol use disorder (AUD). METHOD: We recruited 102 AUD inpatients with baseline depressive symptoms, indicated by scores ≥6 on the Quick Inventory of Depressive Symptomatology Self-Report Japanese Version (QIDS-SR-J) pre-detoxification. Post-4-week abstinence, remission was defined as QIDS-SR-J scores <6. Patients were classified into remitted (n = 51) and persistent (n = 51) groups. Comparative analyses were conducted using patient profiles and the Drinking Behavior Pattern 20-item Questionnaire (DBP-20). Logistic regression identified factors related to post-abstinence persistent depression. Receiver operating characteristic curve analysis determined DBP-20 cutoff scores differentiating between persistent and remitted depression. RESULTS: The persistent group exhibited higher scores in the DBP-20 "coping with negative affect" subscale. Logistic regression showed low education, unemployment, and using alcohol for coping as significant factors for persistent depression. Conversely, an automatic drinking pattern indicated natural remission post-abstinence. A subscale score of ≥8 in alcohol use for coping, especially among unemployed patients, predicted persistent depression (sensitivity 86.8%, positive predictive value 73.3%). CONCLUSION: Unemployed patients with AUD using alcohol to cope with negative affect may experience residual depression even after detoxification. In contrast, patients with AUD with predominantly automatic drinking behavior may exhibit natural remission post-abstinence.

Use of fidget and drinking behaviour in combination with facial infrared thermography for diagnosis of bovine respiratory disease in a spontaneous model.

Bovine respiratory disease (BRD) is a highly prevalent multi pathogen infectious disease (70-80%) in newly received feedlot cattle, causing significant economic losses and reduced animal welfare. Current BRD diagnosis involves stressful and invasive methods that can increase the incidence and transmission of BRD. An alternative is the use of an automated infrared thermography (IR) platform that can monitor facial temperature and behaviour traits to diagnose BRD in a non-invasive manner. The objective of this study was to investigate the use of fidget and drinking behaviours in conjunction with facial temperature as method of BRD diagnosis in beef calves. Sixty-five weaned calves (N = 65) were monitored over a 21-d period after 6 h transportation to predispose calves to BRD infection. Data collected from an automated IR platform placed at a water station included the number of IR frames during drinking (Fidget), number of drinking visits (Drinking bouts), total drinking duration, average drinking duration, average cheek temperature (AVG temp), and maximum orbital temperature (Max temp). Fidget, drinking behaviours, and IR were compared to a clinical score assessment based on respiratory, digestive, and lethargy signs (visual observation) and haematology analysis using a receiver operating characteristics curve analysis to identify the accuracy of each metric and combinations of metrics for BRD diagnosis. The greater accuracies observed were Fidget, Youden's index (J): 0.25 J), Drinking bout (0.28 J), and Total drinking duration (0.22 J). The average IR temperature accuracy resulted in 0.88 J and Max temp 0.77 J. Thirty-five combinations of drinking behaviour and facial IR metrics were evaluated to identify BRD calves. Optimum accuracy (100%) was achieved when combining Fidget, Drinking bout, Average drinking duration, AVG temp, and Max temp 1.00 J. Similar evaluations were performed at 48 and 24 h before d 0 using the most accurate Fidget, Drinking behaviour, and IR combination, resulting in 0.44 J 48 h prior to d 0 and 0.45 J 24 h prior to d 0. Combining fidget and drinking behaviour metrics increased the sensitivity to detect the onset of BRD infection and the specificity to discriminate true positive BRD calves from true negative BRD calves.

Hibernating female big brown bats (Eptesicus fuscus) adjust huddling and drinking behaviour, but not arousal frequency, in response to low humidity.

Many mammals hibernate during winter, reducing energy expenditure via bouts of torpor. The majority of a hibernator's energy reserves are used to fuel brief, but costly, arousals from torpor. Although arousals likely serve multiple functions, an important one is to restore water stores depleted during torpor. Many hibernating bat species require high humidity, presumably to reduce torpid water loss, but big brown bats (Eptesicus fuscus) appear tolerant of a wide humidity range. We tested the hypothesis that hibernating female E. fuscus use behavioural flexibility during torpor and arousals to maintain water balance and reduce energy expenditure. We predicted: (1) E. fuscus hibernating in dry conditions would exhibit more compact huddles during torpor and drink more frequently than bats in high humidity conditions; and (2) the frequency and duration of torpor bouts and arousals, and thus total loss of body mass would not differ between bats in the two environments. We housed hibernating E. fuscus in temperature- and humidity-controlled incubators at 50% or 98% relative humidity (8°C, 110 days). Bats in the dry environment maintained a more compact huddle during torpor and drank more frequently during arousals. Bats in the two environments had a similar number of arousals, but arousal duration was shorter in the dry environment. However, total loss of body mass over hibernation did not differ between treatments, indicating that the two groups used similar amounts of energy. Our results suggest that behavioural flexibility allows hibernating E. fuscus to maintain water balance and reduce energy costs across a wide range of hibernation humidities.

Repeated Δ-9-Tetrahydrocannabinol administration dose dependently increases stablished schedule-induced drinking.

RATIONALE: Schedule-induced drinking (SID) reproduces an excessive and repetitive behavioural pattern that has led to propose this procedure as an animal model to study compulsive behaviours. Although it is known that cannabis can cause several adverse effects, in recent years there has been great interest in the medical application of cannabis derivatives for obsessive-compulsive related disorders. OBJECTIVES: The present study investigated the effects of repeated THC administration on rates of previously acquired SID, as well as the possible alteration of its temporal distribution along inter-food intervals. METHODS: Male Wistar rats acquired SID under a 30 min fixed-time 30-sec food delivery schedule (from 30 to 43 sessions to reach a stable level). Thereafter, 5 or 10 mg/kg daily i.p. injections of THC or vehicle were repeatedly administered for 7 days to evaluate the effects on SID. RESULTS: Repeated THC administration at a dose of 5 mg/kg resulted in an increase on licking. Surprisingly, no effects on SID were observed with the 10 mg/kg dose. However, magazine entries were reduced with both THC doses. THC also modified the temporal distributions of licking and magazine entries during inter-food intervals. CONCLUSIONS: The present results show that repeated THC administration may (i) increase induced licking at moderate doses, (ii) reduce magazine entries, and (iii) affect the temporal pattern of SID. These findings suggest that THC does not appear to be beneficial to reduce compulsive behaviour in this animal model, while another collateral effect of THC -such as a greater habitual-like behaviour- needs to be considered.

Recurrent severe hypernatraemia in a young patient: a disconnect between osmoreceptor function and drinking behaviour.

Chronic hypernatraemia is a rare clinical entity. In the younger population, hypernatraemia is often a consequence of failure to generate thirst in response to osmotic stimuli.We report the case of a male patient admitted with severe hypernatraemia (plasma sodium 175 mmol/L) on return from holidays. His urine was maximally concentrated at 894 mOsm/kg-suggestive of normal vasopressin reserve. MRI of the brain showed a large extra-axial cyst, with preservation of the posterior pituitary bright spot. Formal osmoregulatory studies demonstrated normal osmoregulated vasopressin secretion and normal thirst, but no appropriate drinking behaviour.This patient illustrates a unique pathophysiological disconnect between thirst appreciation and the central drive to drink, in the context of normal osmoregulatory function. It is likely that this disconnect is related to the patient's large intracranial cyst.The management challenge is to maintain appropriate fluid intake in order to prevent recurrent severe hypernatraemia.

Longitudinal Relations Among Parental Substance Use Disorder and Adolescent Drinking Behavior: The Role of Temperament, Negative Urgency, and Maternal Parenting.

Research suggests that parental substance use disorder is associated with adolescent drinking indirectly through negative urgency, a form of impulsivity that is particularly associated with high-risk drinking. Moreover, childhood mechanisms of risk may play a role in this developmental chain such that childhood temperament and parenting may be mechanisms through which parental substance use disorder is associated with adolescent negative urgency and drinking behavior. Therefore, the current study tested whether parental substance use disorder was indirectly associated with adolescent drinking frequency through childhood temperament (i.e., "dysregulated irritability") and adolescent negative urgency, and whether relations differed by levels of maternal support and consistency of discipline. Data come from a multigenerational, longitudinal study of familial substance use disorder (N = 276, Mage in childhood = 6.28 (SD = 1.16), Mage in adolescence = 15.86 (SD = 1.56), 45.3% female). Findings indicated that parental substance use disorder indirectly predicted adolescent drinking through both childhood dysregulated irritability and adolescent negative urgency (mediated pathways). This indirect relation was stronger at higher vs. lower levels of maternal support but did not vary by maternal consistency of discipline. Parental substance use disorder also indirectly predicted adolescent drinking separately through childhood dysregulated irritability and negative urgency. Findings thus suggest that childhood dysregulated irritability may be an early marker of risk toward high-risk personality traits and behavior in adolescence that are associated with having a parental history of substance use disorder. Findings also suggest that increased maternal support may only be helpful in buffering risk for those with low levels of dysregulated irritability. Prevention efforts focused on childhood emotion regulation and emotion-based action may be useful in preventing adolescent risk behavior.

Analysis of Genetic Polymorphism of Bitter Taste Receptor TAS2R38 and TAS2R46, and Its Relationship with Eating and Drinking Habits in Japanese ToMMo Subjects.

Human type 2 taste receptor (TAS2R) genes encode bitter-taste receptors that are activated by various bitter ligands. It has been said that TAS2R38 may detect bitter substances and then suppress their intake by controlling gustatory or digestive responses. The major haplotypes of TAS2R38 involve three non-synonymous, closely-linked single-nucleotide polymorphisms (SNPs), leading to three amino acid substitutions (A49P, V262A and I296V) and resulting in a PAV or AVI allele. The allele frequency of AVI/PAV was 0.42/0.58 in this study. The genotype frequency distributions of TAS2R38 were 18.32%, 46.95% and 33.95% for AVI/AVI, AVI/PAV and PAV/PAV, respectively, and were in Hardy-Weinberg equilibrium. Five haplotype combinations of minor alleles were identified: AVI/AAV, AVI/AVV, AAI/PAV, AVI/PVV, AVI/AAI, with corresponding frequencies of 0.49%, 0.10%, 0.10%, 0.05%, 0.05%, respectively, in 2,047 Japanese Tohoku Medical Megabank Organization (ToMMo) subjects (2KJPN). The 16 subjects with these minor alleles were excluded from the questionnaire analysis, which found no significant differences among the major TAS2R38 genotypes (AVI/AVI, AVI/PAV and PAV/PAV) in the intake frequency of cruciferous vegetables or in the frequency of drinking alcohol. This result differs from previous data using American and European subjects. This is the first study to analyze the relationship between TAS2R38 genotype and the eating and drinking habits of Japanese subjects. It was also shown that there were no relationships at all between the genetic polymorphism of TAS2R46 and the phenotypes such as clinical BMI, eating and drinking habits among the 3 genotypes of TAS2R46 (∗/∗, ∗/W, W/W) at position W250∗ (∗stop codon).

How Sucrose Preference Is Gained and Lost: An In-Depth Analysis of Drinking Behavior during the Sucrose Preference Test in Mice.

The sucrose preference test (SPT) is a widely used preclinical assay for studying stress-sensitive reward behaviors and antidepressant treatments in rodents, with some face, construct, and predictive validity. However, while stress-induced loss of sucrose preference is presumed to reflect an anhedonic-like state, little detail is known about what behavioral components may influence performance in the SPT in stress-naive or stressed rodents. We analyzed the licking microstructure of mice during the SPT to evaluate how preference is expressed and lost following chronic stress. In stress-naive mice, preference is expressed as both longer and more numerous drinking bouts at the sucrose bottle, compared with the water bottle. We also found evidence that memory of the sucrose bottle location supports preference. Through manipulations of the caloric content of the sweetener or caloric need of the mouse, we found that energy demands and satiety signals do not affect either preference or the underlying drinking behavior. Both acute and chronic stress impaired sucrose location memory and reduced the number of drinking bouts at the sucrose bottle, the latter of which explained the loss of sucrose preference in stress susceptible mice compared with stress resilient mice. Female mice generally exhibited similar drinking behavior to male mice but may be less susceptible to chronic stress and display better memory performance than male mice, both before and after chronic stress. Our data suggest that chronic stress inhibits a sucrose preference by reducing reward seeking behavior without affecting palatability.

Exploratory inference of the ingestive behavior of pigs in the finishing phase in an air-conditioned environment.

The objective of this research is to apply exploratory analysis and modeling associated with abiotic factors, physiological and behavioral variables of swine in the semi-arid region. The experimental design used was completely randomized, in a 3 × 3 factorial scheme, randomly distributed in nine pens, with three animals. The behavior of the animals was recorded using images and analyzed within 10-min interval. The data analysis used was multivariate, using the clustering method (tree diagram) and principal component analysis (PCA), in order to establish the main predictors of swine ingestive behavior, using multiple linear regression models. The PCA showed satisfactory results, in which the lowest eigenvalue observed was 2.82 and the accumulated variance for the treatments ranged from 69.70 to 94% for the first two principal components. Through exploratory data analysis, it was possible to identify the relationship between biotic and abiotic factors with the ingestive behavior of pigs in the finishing phase. Based on the results of the multivariate analysis, the most promising predictor variables for estimating the regression models were determined. Adiabatic evaporative cooling associated with 18 h of light was the combination of factors with the best results, presenting models for eating and drinking behavior, i.e. a complete ingestive characterization.

Microinjection of NMDA-neurotoxin into the superior salivatory nucleus of the rat: Short-term secretory and long-term drinking behavior effects.

The anatomical location of the superior salivatory nucleus (SSN), the site of origin of the parasympathetic preganglionic cell bodies that innervate the submandibular-sublingual salivary glands, is well established in rats. However, as of yet there is no functional data that convincingly shows the secretory nature of this region. Previous studies have not been able to differentiate between interventions on efferent or afferent fibers connected to the SSN versus interventions on the salivatory nucleus itself. Taking advantage of the fact that salivatory neurons express NMDA-receptors on their somas, in the present study SSN cell bodies were activated and lesioned sequentially by means of intracerebral application of NMDA-neurotoxin. In exp. 1 two effects, a short- and a long-term effect, were observed following NMDA administration. The first effect was high submandibular-sublingual saliva secretion during the hour following administration of the neurotoxin and the second was a profound change in drinking behavior once the animals recovered from the lesion. Thus, on post-surgery days 16, 17 and 18, the rats exhibited hyperdipsia in the presence of dry food but not in the presence of wet food. In expt. 2 results showed that saliva hypersecretion observed after NMDA-microinjection was completely blocked by the administration of atropine (a cholinergic blocker) but not after the administration of dihydroergotamine plus propranolol (α and ß-adrenergic blockers, respectively). From a functional perspective, these data suggest that the somata of the parvocellular reticular formation control the secretory activity of the submandibular-sublingual salivary glands and thus constitute the SSN.