The action of proinflammatory cytokines on formation of behavior during early postnatal ontogenesis

The study is devoted to the role of proinflammatory cytokine-interleukin-1beta during early postnatal ontogenesis in formation of behavioral programs. Cytokine was injected in pyrogenic and subpyrogenic doses during 1 week (1, 2 or 3 weeks of life). The behavior was tested in the young (40-45 days) and adult (3 months) rats in the "open field" and "elevated plus maze". The greatest behavior disordes (elevation of act's number and of motor activity, the decrease of investigation activity) are revealed in the young animals treated with IL-Ib during 1 and 3 weeks of life. These behavioral changes were marked in rats injected with pyrogenic and subpyrogenic doses of cytokine. They had a similar tendency in male and female rats. At the age of 3 months, behavior changes revealed in juvenile rats were insignificant.     

Changes in the sensomotor cortex of offspring after chronic intoxication with tobacco smoke through the mother-fetus system

The state of the sensomotor cortex in the offspring of white non-inbred rats, "passively" smoking before mating, during mating and throughout pregnancy time has been investigated. The investigation performed in 14 age groups from the period of birth up to a relative morphological stability (age of 3 months), control and experimental rats (as a whole 281 animals) makes it possible to conclude that certain components of the tobacco smoke are accumulated in the offspring blood and continue to exercise a destructive influence on the neocortex during 2 weeks after birth. The consequence of chronic intoxication of the tobacco smoke through the system mother--fetus is expressed as diffuse and focal decrease of neurons nearly by 1/3 in the sensomotor cortex, especially in the V cytoarchitectonic layer.     

Inhibition of tobacco smoke-induced lung inflammation by a catalytic antioxidant

Cigarette smokers experience airway inflammation and epithelial damage, the mechanisms of which are unknown. One potential cause may be free radicals either in tobacco smoke or produced during persistent inflammation. Inflammation may also be a driving force to cause airway epithelium to undergo changes leading to squamous cell metaplasia. To test whether tobacco smoke-induced inflammation could be reduced by a catalytic antioxidant, manganese(III)meso-tetrakis(N,N'-diethyl-1,3-imidazolium-2-yl) porphyrin (AEOL 10150) was given by intratracheal instillation to rats exposed to filtered air or tobacco smoke. Exposure to tobacco smoke for 2 d or 8 weeks (6 h/d, 3 d/week) significantly increased the number of cells recovered by bronchoalveolar lavage (BAL). AEOL 10150 significantly decreased BAL cell number in tobacco smoke-treated rats. Significant reductions in neutrophils were noted at 2 d and macrophages at 8 weeks. Lymphocytes were significantly reduced by AEOL 10150 at both time points. Squamous cell metaplasia following 8 weeks of tobacco smoke exposure was 12% of the total airway epithelial area in animals exposed to tobacco smoke without AEOL 10150, compared with 2% in animals exposed to tobacco smoke, but treated with AEOL 10150 (p <.05). We conclude that a synthetic catalytic antioxidant decreased the adverse effects of exposure to tobacco smoke.     

The effect of tobacco smoke on the metabolism and function of rat alveolar macrophages.

Alveolar macrophages harvested by bronchopulmonary lavage from rats exposed to tobacco smoke for 30 days ("smokers") showed alterations in oxidative metabolism, lactate production and phagocytosis of inert starch particles when compared with control macrophages. Phagocytosis of viable Staphylococcus aureus was unaffected by tobacco smoke. Glucose oxidation measured by conversion of glucose-1-14C to 14CO2 moderately affected while oxidation of glucose-6-14C to 14CO2 was not. Smokers routinely yielded fewer cells than controls, though these cells contained approximately 17% more protein than did controls. Opsonization of particles was not necessary for macrophages from either smoker or control animals to manifest a respiratory burst and increased superoxide and hydrogen peroxide release during phagocytosis. The glycolytic inhibitors, sodium fluoride and iodoacetamide, while effectively blocking glycolysis, did not inhibit phagocytosis by macrophages from either group. The results reported clearly distinguish alveolar macrophages from other phagocytic cells (peritoneal macrophages and polymorphonuclear leukocytes) and suggest a state of non-specific activation caused by exposure to tobacco smoke.     

Chemopreventive effects of hydroxymatairesinol on uterine carcinogenesis in Donryu rats

Hydroxymatairesinol (HMR), obtained from the heartwood of spruce (Picea abies), has been demonstrated to exert chemo-preventive effects on the development of mammary tumors in rats. To examine the influence of HMR on uterine carcinogenesis, adult Donryu rats were initiated with a single intrauterine treatment of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) at 11 weeks of age and fed thereafter 0, 200, or 600 ppm HMR mixed in the soy-containing diet until 15 months of age. Incidences of uterine adenocarcinoma in both 200 and 600 ppm HMR-dosed groups were significantly reduced to 11% and 15%, respectively, less than 50% of 0 ppm, at the end of the experiment (P < 0.05). A delay in the start of persistent estrus by HMR was observed at 8 months of age compared with controls given carcinogen alone. From urinalysis, HMR was metabolized mainly to enterolactone and hydroxyenterolactone. These findings suggest that HMR or its metabolites exert chemo-preventive effects in the rat ENNG-uterine carcinogenesis model.     

Influence of females on conflict among wild rats

Ten male wild rats, Rattus norvegicus , trapped as adults, ("residents") were each kept singly in large cages. During each of four weeks they were exposed daily, on five successive days, for 15 min, to a strange adult male of the same species. In weeks 1 and 3 the residents were alone; in weeks 2 and 4 two adult females were present. A further four males were similarly studied for three weeks; in weeks 1 and 3 females were present, and in week 2 they were absent. All residents except two attacked strange males more when females were present, though the females played no direct part in the encounters. There was evidence of a positive correlation between a 'threat posture' and the duration of attack. The theoretical implications of these observations are discussed.     

Expression of cytochrome CYP2B1/2 in nonpregnant, pregnant and fetal rats exposed to tobacco smoke

Four-month-old female Wistar rats were exposed for 20 days to tobacco smoke obtained from non-filter cigarettes. During the exposure, concentration of tobacco smoke was monitored indirectly by measuring the CO level (1500 mg/m3 air). The efficacy of exposure was assessed by measuring urine nicotine and cotinine levels. Cigarette smoke did not change total cytochrome P450 and b5 protein levels in any of the organs studied, and most of these organs did not show any changes in the activity of reductases associated with these cytochromes. Following exposure to tobacco smoke, fetal rat liver expressed CYP2B1/2 protein; in newborns (day 1) both liver and lung showed CYP2B1/2 protein expression and very low pentoxyresorufin O-dealkylase activity. Western blot analysis of adult liver, lung, heart, but not of brain microsomes, showed that tobacco smoke induced CYP2B1/2 in both nonpregnant and pregnant rats, though its expression was lower in the livers and hearts of pregnant females. In the rat and human placenta, neither rat CYP2B1/2 nor human CYP2B6 showed basal or tobacco smoke-induced expression at the protein level. This study shows clearly that the expression of CYP2B1/2, which metabolizes nicotine and some drugs and activates carcinogens, is controlled in rats by age-, pregnancy-, and tissue-specific regulatory mechanisms.     

Testosterone prevents but not reverses anhedonia in middle-aged males and lacks an effect on stress vulnerability in young adults

Middle-aged male rats are more vulnerable than young adult ones to develop anhedonia when exposed to chronic mild stress (CMS). Clinical studies support the idea that in aged subjects the low testosterone (T) levels are related with their higher stress vulnerability and that this hormone possesses antidepressant-like actions. In this study we evaluated the role of gonadal hormones--mainly T--on the depressive-like behavior of middle-aged and young adult male rats submitted to CMS. In middle-aged rats we analyzed the effect of T restitution (at the levels of young adult animals) given 3 weeks before (experiment 1) or 3 weeks after (experiment 2) anhedonia development (indicated by a reduction in sucrose solution intake). T restitution before CMS effectively prevented anhedonia but failed to reverse it once installed. In young adult rats we studied if orchidectomy increased stress vulnerability and found that it failed to modify sucrose intake. These results indicate a stress-dependent differential effect of T in middle-aged rats an age differential role of gonadal hormones on the vulnerability to develop anhedonia. The results suggest that T is a resilience factor in middle-aged but not in young adult males.     

Differential effects of oestrogen on developing and mature uterine sympathetic nerves

Oestrogen is a key factor in the remodelling of uterine sympathetic nerves during puberty and the oestrous cycle; these nerves are influenced by changes in their target uterine tissue. The magnitude of oestrogen-induced responses might however be influenced by the maturation stage of sympathetic nerve fibres, the age of the neurons and/or the developmental state of the uterus. We have therefore compared the sympathetic innervation of the uterus following chronic oestrogen treatment of infantile/prepubertal and young adult intact and ovariectomised rats. Treatment of infantile/prepubertal rats resulted in the complete loss of intrauterine noradrenaline (NA)-labelled sympathetic nerves and a marked reduction in the total NA content in the uterine horn. Chronic treatment of young adult rats had little effect. To examine whether the age of the neurons or the degree of development of the uterus determined responsiveness of nerves to oestrogen, we assessed the effects of oestrogen on the sympathetic reinnervation of intraocular transplants of young adult uterine myometrium into ovariectomised adult host rats. Early treatment (10 days post-transplantation) resulted in less sympathetic innervation than late treatment (30 days post-transplantation). Measurements of nerve growth factor (NGF) levels in the uterine horn of control rats before and after puberty and following infantile/prepubertal chronic oestrogen treatment and acute oestrogen treatment of young adult rats revealed a coordinated increase between the growth of the uterus and NGF protein levels. Thus, developing and recently regrown sympathetic nerves are more susceptible to oestrogen-induced changes in the uterus than mature nerves, differential susceptibility is not related to the age of the neurons or the developmental state of the uterus and changes in NGF protein do not account for the differential susceptibility of developing and mature uterine sympathetic nerve fibres to oestrogen. Growing sympathetic fibres are more vulnerable to oestrogen than mature fibres and nerve fibres that have been in contact for longer periods with their target become less susceptible to oestrogen.     

Adaptive responses of 25-hydroxyvitamin D3 1-alpha hydroxylase expression to dietary phosphate restriction in young and adult rats

Regulation of vitamin D metabolism alters with age. The present study is undertaken to investigate if the loss of renal 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) production in response to dietary phosphate (P) restriction in adult rats is due to an alteration in the renal expression of 25-hydroxyvitamin D(3) 1-alpha hydroxylase (1-OHase). Young (4-6 weeks old) and adult (12-14 weeks old) male Sprague Dawley rats were fed either normal P (NPD) or low P diet (LPD) for 0-5 days. Basal expression of 1-OHase protein was higher in adult rats. Young rats, but not adult rats, significantly increased 1-OHase protein and mRNA expressions in response to LPD in a time-dependent manner. To determine if the stability of renal 1-OHase protein changes with LPD feeding, young and adult rats fed either NPD or LPD for 5 days were injected intravenously with cycloheximide (CHX), a protein synthesis inhibitor. CHX decreased 1-OHase protein expression in young rats fed NPD. However, CHX did not alter 1-OHase protein expression in young rats fed LPD nor in adult rats fed either diet. The results indicate that the stability of renal 1-OHase protein increased with age and that LPD increased its stability only in young rats.     

Transition from cytosolic to mitochondrial thymidine kinase during development in human fetal tissues

The transition from cytosolic ("fetal") to mitochondrial ("adult") thymidine kinase, as detected by electrophoresis, was examined in six human fetal tissues of gestational ages 11-40 weeks. In all tissues there was an early period during development in which only the fetal form was detected, followed by a transitional period in which both fetal and adults forms were present, followed by a later period in which only the adult enzyme occurred. Transitional periods were 23-25 wk. gestational age for colon, 13-15 wk. for kidney, 18-20 wk. for liver, 14-18 wk. for lung, 34-36 wk. for serum, and 25-28 wk. for thyroid. In all cases, only the adult form was present by the time of birth and persisted during the first 18 months of extrauterine life. The adult form, but not the fetal form, was inhibited by dCTP.     

Aging Contributes to Inflammation in Upper Extremity Tendons and Declines in Forelimb Agility in a Rat Model of Upper Extremity Overuse

We sought to determine if tendon inflammatory and histopathological responses increase in aged rats compared to young rats performing a voluntary upper extremity repetitive task, and if these changes are associated with motor declines. Ninety-six female Sprague-Dawley rats were used in the rat model of upper extremity overuse: 67 aged and 29 young adult rats. After a training period of 4 weeks, task rats performed a voluntary high repetition low force (HRLF) handle-pulling task for 2 hrs/day, 3 days/wk for up to 12 weeks. Upper extremity motor function was assessed, as were inflammatory and histomorphological changes in flexor digitorum and supraspinatus tendons. The percentage of successful reaches improved in young adult HRLF rats, but not in aged HRLF rats. Forelimb agility decreased transiently in young adult HRLF rats, but persistently in aged HRLF rats. HRLF task performance for 12 weeks lead to increased IL-1beta and IL-6 in flexor digitorum tendons of aged HRLF rats, compared to aged normal control (NC) as well as young adult HRLF rats. In contrast, TNF-alpha increased more in flexor digitorum tendons of young adult 12-week HRLF rats than in aged HRLF rats. Vascularity and collagen fibril organization were not affected by task performance in flexor digitorum tendons of either age group, although cellularity increased in both. By week 12 of HRLF task performance, vascularity and cellularity increased in the supraspinatus tendons of only aged rats. The increased cellularity was due to increased macrophages and connective tissue growth factor (CTGF)-immunoreactive fibroblasts in the peritendon. In conclusion, aged rat tendons were overall more affected by the HRLF task than young adult tendons, particularly supraspinatus tendons. Greater inflammatory changes in aged HRLF rat tendons were observed, increases associated temporally with decreased forelimb agility and lack of improvement in task success.     

Hypertension after bilateral kidney irradiation in young and adult rats

The mechanism of a rise in blood pressure after kidney irradiation is unclear but most likely of renal origin. We have investigated the role of the renin-angiotensin system and dietary salt restriction in the development of systolic hypertension after bilateral kidney irradiation in young and adult rats. Three to 12 months after a single X-ray dose of 7.5 or 12.5 Gy to both kidneys of young and adult rats, the systolic blood pressure (SBP) and plasma renin concentration (PRC) were measured regularly. A single X-ray dose of 12.5 Gy caused a moderate rise in SBP and a slight reduction in PRC in both young and adult rats. A dose of 7.5 Gy did not significantly alter the SBP or PRC during the follow-up period of 1 year. In a second experiment, the kidneys of young rats received an X-ray dose of 20 Gy. Subsequently, rats were kept on a standard diet (110 mmol sodium/kg) or a sodium-poor diet (10 mmol sodium/kg). On both diets, SBP started to rise rapidly 3 months after kidney irradiation. Sodium balance studies carried out at that time revealed an increased sodium retention in the irradiated rats compared to controls on the same diet. In rats on a low sodium intake, there was neither a delay nor an alleviation in the development of hypertension. Compared to controls, the PRC tended to be lower in irradiated rats up to 4 months after irradiation. Subsequently, malignant hypertension developed in all 20 Gy rats, resulting in pressure natriuresis, stimulating the renin-angiotensin system. Our findings indicated that hypertension after bilateral kidney irradiation was not primarily the result of an activation of the renin-angiotensin system. Although there were some indications that sodium retention played a role, dietary sodium restriction did not influence the development of hypertension.     

Dissociable influences of auditory object vs. spatial attention on visual system oscillatory activity

Given that both auditory and visual systems have anatomically separate object identification ("what") and spatial ("where") pathways, it is of interest whether attention-driven cross-sensory modulations occur separately within these feature domains. Here, we investigated how auditory "what" vs. "where" attention tasks modulate activity in visual pathways using cortically constrained source estimates of magnetoencephalograpic (MEG) oscillatory activity. In the absence of visual stimuli or tasks, subjects were presented with a sequence of auditory-stimulus pairs and instructed to selectively attend to phonetic ("what") vs. spatial ("where") aspects of these sounds, or to listen passively. To investigate sustained modulatory effects, oscillatory power was estimated from time periods between sound-pair presentations. In comparison to attention to sound locations, phonetic auditory attention was associated with stronger alpha (7-13 Hz) power in several visual areas (primary visual cortex; lingual, fusiform, and inferior temporal gyri, lateral occipital cortex), as well as in higher-order visual/multisensory areas including lateral/medial parietal and retrosplenial cortices. Region-of-interest (ROI) analyses of dynamic changes, from which the sustained effects had been removed, suggested further power increases during Attend Phoneme vs. Location centered at the alpha range 400-600 ms after the onset of second sound of each stimulus pair. These results suggest distinct modulations of visual system oscillatory activity during auditory attention to sound object identity ("what") vs. sound location ("where"). The alpha modulations could be interpreted to reflect enhanced crossmodal inhibition of feature-specific visual pathways and adjacent audiovisual association areas during "what" vs. "where" auditory attention.     

Arrest of developmental conversion of type II to type I fibres after suspension hypokinesia

Summary The effects of hypokinesia and of the lack of gravity on muscle fibres, fibre type composition and myosin light chain pattern, as well as on muscle mechanoreceptors were investigated in the slow-twitch soleus (SOL) and fast-twitch extensor digitorum longus (EDL) muscles of young growing and adult rats after suspension hypokinesia (SH) of their hind limbs. The animals were suspended by their tail so that their hind limbs were relieved of their normal weight-bearing function for 3–6 weeks.In normal 3-to 4-week-old rats the SOL contained about 50% type I fibres and their percentage increased up to about 80% until the 10th week, with simultaneous reduction of type IIA fibres. After 3 to 6 weeks of suspension treatment maintained from 3-to, 4-week-old rats up to 6 to 10 weeks of age, the SOL still only contained about 50% of type I fibres. The content of fast LC₁ and LC₂ in the SOL of 6-week-old rats after 3 weeks of suspension was higher than that of control litter-mates reflecting the higher occurrence of IIA fibres in the suspended solei. No changes in fibre type composition were observed after SH performed in adult rats.SH thus leads, in young animals, to the arrest of conversion of type IIA to type I fibres resulting in the persistence of the fibre type composition and of the myosin light chain pattern corresponding to those present in the SOL at the time of the onset of suspension. In both young and adult rats, SH markedly decreased the mass and the mean cross-sectional area of the SOL, mainly due to the severe atrophy of type I fibres. We observed no signs indicating conversion of type I back to type IIA muscle fibres due to the SH either in young or adult animals.In contrast to profound changes in the SOL, no significant differences were found in the EDL in any of the parameters studied.No changes in the investigated parameters of muscle spindles and tendon organs were observed after SH, performed either in young or in adult rats.We thus conclude that SH leads to muscle atrophy and that it influences mainly or exclusively type I fibres in muscles with a postural function such as the SOL. It is suggested that in young rats SH arrests changes in the SOL motoneurones, which remain unable to ensure the normal developmental transformation of type IIA into type I fibres, thus preventing conversion of the SOL into a typical slow-twitch muscle.     

Uterine phenotype of young adult rats exposed to dietary soy or genistein during development

Dietary soy intake is associated with protection from breast cancer, but questions persist on the potential risks of the major soy isoflavone genistein (GEN) on female reproductive health. Here, we evaluated intermediate markers of cancer risk in uteri of cycling, young adult Sprague-Dawley rats lifetime exposed to one of three AIN-93G semipurified diets: casein (CAS), soy protein isolate (SPI+ with 276 mg GEN aglycone equivalents/kg) and CAS+GEN (GEN at 250 mg/kg). Postnatal day 50 (PND50) rats lifetime exposed to GEN or SPI+ had similar uterine luminal epithelium height, myometrial thickness, endometrial gland numbers, endometrial immunoreactive proliferating cell nuclear antigen (PCNA), and serum estrogen and progesterone, as CAS-fed rats. GEN-fed rats showed modestly increased apoptosis in uterine glandular epithelium, compared to those of CAS- or SPI+-fed groups. Diet had no effect on the uterine expression of genes for the tumor suppressors PTEN, p53 and p21, and the apoptotic-associated proteins Bcl2, Bax and progesterone receptor. Uterine tissue and serum concentrations of total GEN were higher in rats fed GEN than in those fed SPI+. Human Ishikawa endocarcinoma cells treated with GEN-fed rat serum tended to exhibit increased apoptotic status than those treated with CAS-fed rat serum. Exogenously added GEN (0.2 and 2 microM) increased, while estradiol-17beta (0.1 microM) decreased Ishikawa cell apoptosis, relative to untreated cells. Results suggest that lifetime dietary exposure to soy foods does not alter uterine cell phenotype in young adult rats, while GEN, by enhancing uterine endometrial glandular apoptosis in vivo and in vitro, may confer protection against uterine carcinoma. Given its limited influence on uterine phenotype of young adult females, GEN, when taken as part of soy foods or as supplement, should be favorably considered for other potential health benefits.     

Development of optokinetic neuronal responses in the pretectum and horizontal optokinetic nystagmus in unilaterally enucleated rats

Responses of single units to constant-velocity rotations of the visual surround (0.25-10 degrees/s) were studied in the pretectum of unilateral enucleated rats at different ages. Enucleation was performed either in the first postnatal week ("early" enucleated rats) or in the adult stage ("late" enucleated rats). Pretectal unitary responses were recorded in early enucleated animals at postnatal day 20-21, 36-49 and, in both experimental groups, in the adult stage. Optokinetic ocular nystagmus was studied in early and late enucleated rats in the adult stage. Gain of optokinetic nystagmus in temporo-nasal stimulus direction was not changed for visual surround rotations of up to 20 degrees/s compared to controls in monocular viewing conditions. At higher stimulus velocities, however, the gain dropped. In naso-temporal stimulus direction, optokinetic nystagmus was improved in gain for optokinetic pattern motions of up to 5-10 degrees/s. There were only minor differences in the gain behaviour of optokinetic nystagmus obtained from early or late enucleated rats. The optokinetic responses of pretectal neurons obtained from early and late enucleated rats were reduced in sensitivity by more than 50%. The response patterns of neurons recorded in the contralateral pretectum relative to the intact eye were shifted by a large amount from directional selective to directional nonselective response types. No such changes were obtained in the ipsilateral pretectum. In contrast to normal rats, there were very few directional selective units responding to temporo-nasal pattern motion. On the other hand, a large proportion of directional selective units responded to naso-temporal pattern motion. These latter units were found in both early and late enucleated rats. A similar response type has previously been described for intact young rats but not for adult rats. The velocity tuning curve of pretectal units studied in the adult stage was similar in shape in early and late enucleated rats and resembled that obtained from enucleated or intact young animals. Our results show that response sensitivity, direction and velocity tuning of pretectal units depend crucially on retinal afferent input originating from both eyes. The data suggest that the response characteristics of many of the pretectal units that are considered to be important for mediating optokinetic reflexes depend on interpretectal signal processing using commissural connections. There is very little evidence for an adaptative structural plasticity of the optokinetic system following loss of one eye. The reduced asymmetry observed in gain of optokinetic responses correlated in both early and late enucleated rats with the shifts observed in the distribution of pretectal unitary response patterns.     

Type of behavior and superoxide dismutase activity in the brain of rats (a comparison of 2 Tryon strains)

Differences in the type of behaviour in capable ("maze-bright") and incapable ("maze-dull") Tryon rats have been demonstrated in the situation with pain-irritated partner by the method of "emotional resonance". Most "bright" rats belonged to the type not avoiding the signals of another pain-irritated rat, they revealed a persistent ecologically defensive reaction of preferring a small closed space. The type of anxiety behaviour prevailed in the group of "dull" rats. In the open field test "bright" rats were characterized by low locomotor activity and high level of defecation and "dull" rats by high activity and low defecation. Increased levels of superoxide dismutase activity and high content of thiobarbituric acid-reactive material were observed in brains of dull rats. The interrelations between behavioural and molecular levels of defensive response to stress is discussed.     

Food-associated calls in rhesus macaques (Macaca mulatta): I. Socioecological factors

Upon discovering food, free-living rhesus macaques (Macaca mulatta)on the island of Cayo Santiago, Puerto Rico, produce a complexof vocal signals consisting of five acoustically distinguishablecalls. This report examines the socioecological factors elicitingcall production and the information protentially conveyed toothers. The primary contexts for three vocalizations ("warbles," "harmonicarches, " and "chirps") are encounters with rareand highly preferred foods (e.g., coconut). Two other vocalizations("coos" and "grunts") are produced both in food (primarily provisionedchow) and in nonfood contexts, such as during mother-infantseparation and grooming interactions. Grunts given upon encounteringfood are acoustically distinct from those given in nonfood contexts.In contrast, coos associated with food are statistically indistinguishablefrom coos given in other contexts. When conspecitics hear thesefood-associated calls, they typically approach the caller. Coosare less likely to lead to approach than other food-associatedcalls, Results from all-day follows on adult males and adultfemales reveal that changes in hunger level influence call ratebut not call type; the different call types are produced throughoutthe day. We infer that the structure of food-associated callsprovides information about the quality of the food discovered,whereas call rate conveys information about the relative hungerlevel of the caller. In this population, adult males give fewerfood-associated calls than adult females. In addition, femaleswithin large matrilines call more than females within smallermatrilines, and males who are resident in a group are more vocalthan peripheral males.