Deprivation Treatments Research Articles

Effect of Restricted Feeding Regimes on Compensatory Growth and Body Composition of Red Sea Bream, Pagrus major

Abstract Compensatory growth of red sea bream, Pagrus major, during feed deprivation and after refeeding was investigated. Groups of three fish each were allocated into 28 cages. Fish were fed by a commercial feed to satiation twice a day. Four feeding groups of fish were prepared: one group with continuous feeding (C) for 9 wk and three other groups with feed deprivation for 1 wk (F1) in Week 3, 2 wk (F2) from Week 2 to Week 3, and 3 wk (F3) from Week 1 to Week 3, respectively. All fish in the feed deprivation treatments resumed feeding in Week 4. The full compensatory growth was achieved in F1 and F2 fish after refeeding for the first 3 wk but in F3 fish after refeeding for the second 3 wk. Specific growth rate and feed conversion efficiency in all fish experiencing fasting were higher than those of control fish after first 3 wk of refeeding. At the end of feed deprivation in Week 3, crude protein, crude lipid, and energy content of all fish experiencing fasting were lower than those of the control fish. These results indicated that red sea bream experienced 1‐, 2‐, and 3‐wk fasting could achieve full compensatory growth in the 9‐wk feeding trial.

Nest mate size, but not short-term need, influences begging behavior of a generalist brood parasite

Hosts of generalist brood parasites often vary with regards to their life-history traits, and these differences have the potential to influence the competitive environment experienced by brood-parasitic nestlings. Although begging by brood parasites is more exaggerated than their hosts, it is unclear if generalist brood parasites modulate their begging behavior relative to host size. I examined the begging behavior of brown-headed cowbird (Molothrus ater) nestlings when competing against nest mates that differ in size and under different levels of short-term need. Cowbird nestlings begged on nearly all feeding visits, responded to adults as fast as (or faster than) their nest mates, and typically begged more intensively than their nest mates. Latency to beg, time spent begging, and maximum begging posture of cowbirds were similar during supplementation and deprivation treatments, indicating begging intensity was not influenced by short-term need. Time spent begging by cowbirds varied among hosts of 3 different sizes when short-term need was standardized, suggesting that nest mate size strongly influenced begging behavior. Cowbirds obtained more food when competing against an intermediate-sized host due to lower provisioning rates of small hosts or because of increased competitive ability of large host nestlings. Overall, cowbirds obtained the greatest volume of food per unit time spent begging when competing against intermediate hosts, but this value approached that of the small host when adjusted for modal brood size. These results demonstrate that cowbirds adjust their begging relative to the size of the hosts against which they compete but not to levels of short-term need. Key words: begging behavior, begging intensity, brown-headed cowbird, Molothrus ater, nestling competition, short-term need. [Behav Ecol]

Brain-Derived Neurotrophic Factor Plays a Role as an Anorexigenic Factor in the Dorsal Vagal Complex

Brain-derived neurotrophic factor (BDNF) has recently been implicated as an anorexigenic factor in the central control of food intake. Previous studies focused on the hypothalamus as a probable site of action for this neurotrophin. It was demonstrated that BDNF is an important downstream effector of melanocortin signaling in the ventromedial hypothalamus. In this study, we addressed whether BDNF can modulate food intake in the hindbrain autonomic integrator of food intake regulation, i.e. the dorsal vagal complex (DVC). To this end, we used two complementary methodological approaches in adult rats. First, we measured the effects of intraparenchymal infusions of exogenous BDNF within the DVC on food intake and body weight. Second, we measured the endogenous BDNF protein content in the DVC and hypothalamus after food deprivation, refeeding, or peripheral treatments by the anorexigenic hormones leptin and cholecystokinin (CCK). BDNF infusion within the DVC induced anorexia and weight loss. In the DVC, BDNF protein content decreased after 48 h food deprivation and increased after refeeding. Acute and repetitive peripheral leptin injections induced an increase of the BDNF protein content within the DVC. Moreover, peripheral CCK treatment induced a transient increase of BDNF protein content first in the DVC (30 min after CCK) and later on in the hypothalamus (2 h after CCK). Taken together, these results strongly support the view that BDNF plays a role as an anorexigenic factor in the DVC. Our data also suggest that BDNF may constitute a common downstream effector of leptin and CCK, possibly involved in their synergistic action.

Signalling of hunger when offspring forage by both begging and self-feeding

Studies on vertebrate species in which the offspring obtain food only from their parents have shown that offspring begging conveys information on offspring hunger. It is unclear whether begging can also convey information on hunger in partially begging species, in which the offspring, from hatching, obtain food partly through begging for food from the parents and partly through self-feeding. In partially begging species, offspring hunger state could reflect the amount of food obtained by self-feeding in addition to the amount obtained from the parent, and the offspring could respond to hunger by self-feeding instead of begging. To test whether begging reflected the current hunger state of offspring in the partially begging beetle Nicrophorus vespilloides, we subjected larvae to two deprivation treatments: no access to any food for 2h (i.e. food-deprived larvae) and no food provided by the parent (i.e. self-feeding larvae). Larvae of both treatments spent more time begging than did control larvae, which had access to food both from the parents and by self-feeding. Furthermore, the amount of begging differed between the treatments, with food-deprived larvae spending more time begging than the self-feeding ones. We conclude that, in partially begging species, food obtained through both foraging strategies, i.e. begging for food from parents and self-feeding, contribute to the offspring's current hunger state, and that begging can convey information about it.

Effect of partial water deprivation on the performance and carcass characteristics of broler chickens exposed to selected durations of water deprivation in the humid tropical environment

A study was conducted to assess the effects of partial water deprivation on the biologic performance and carcass qualities of broiler chickens raised in a humid tropical environment. There were 2 experiments involving the use of 280 and 500 broiler chickens of mixed sexes respectively. These birds were raised to 4 weeks of age and then subjected to selected durations of water deprivation treatments which lasted for 2 and 5 weeks respectively. Water deprivation exposure had no significant effect (P>0.05) on body weight, weight gain, feed intake, feed conversion ratio and mortality following 2 weeks of treatment in the first experiment. However, in the second experiment, when the birds were exposed to longer period of water deprivation (5 weeks), body weight and water consumption were significantly affected (P

Molecular basis of co-targeting prostate tumor and stroma.

Prostate cancer is one of the leading causes of cancer death in Northern American men. The lethal phenotypes of human prostate cancer are characterized by progression to androgen-independence (Al) and a propensity to form osseous metastases. In approximately 80% of cases, prostate cancer colonizes bone and elicits a characteristic osteoblastic reaction. The bone metastases are initially sensitive to androgen deprivation treatments, but with time the cancer will eventually progress into an Al stage for which there is currently no effective treatment. Once initial hormonal therapy has failed, median survival of prostate cancer patients with bone metastases is less than 1 year (Tu et al. [2001] Lancet 357:336-341). Novel therapeutic and preventive strategies are needed to decrease morbidity and mortality of this disease.

Nutrient deprivation and the subsequent survival of biocontrol Pseudomonas fluorescens CHA0 in soil

The effects of deprivation of multiple nutrients or of selected single nutrients (C, S, N, or P) for 7 d in vitro on the subsequent persistence of the biocontrol agent Pseudomonas fluorescens CHA0 in natural soil were investigated. Experiments were carried out with the spontaneous rifampicin-resistant mutant CHA0-Rif and the strain was monitored in vitro and in soil using colony counts (on plates containing rifampicin), Kogure’s direct viable counts and total cell counts (by immunofluorescence microscopy). Single nutrient or multiple nutrient deprivation in vitro did not affect the colony-forming ability of CHA0-Rif cells. However, cell length of the strain was smaller in all nutrient deprivation treatments but one (P deprivation) when compared with cells from log-phase cultures. Once introduced into soil, CHA0-Rif cells from log-phase cultures persisted up to 14 d as culturable cells, and their population numbers (10 8 CFU (g soil) −1) had not declined. The strain was recovered at lower cell numbers at subsequent samplings, regardless of the method used for cell counts, and at 48 d about 90% of the cells had lost both their ability to respond to Kogure’s viability test and to form a colony on plate. Cells of CHA0-Rif deprived of a single nutrient persisted similarly to log-phase cells once introduced into soil. In contrast, deprivation of CHA0-Rif cells for multiple nutrients prior to their introduction into soil resulted in the early occurrence (i.e. within hours of soil inoculation) of cells that had lost their colony-forming ability and that did not respond to Kogure’s viability test. This suggests that the lack of a single nutrient (other than C, S, N or P) or deprivation of a combination of several nutrients, under in vitro conditions, had a negative effect on the subsequent survival of CHA0-Rif in soil.

Effect of winter food deprivation on growth and sexual maturity of Atlantic salmon (Salmo salar) in seawater

By identifying individual Atlantic salmon (Salmo salar) smolts (age 1+, mean weight 95 g), a tank study with four treatments (n = 175 fish per tank) indicated that maturation as grilse is associated with changes in somatic growth over many months, from July of the first summer in seawater onwards. The grilse rate in both sexes was associated with a relatively high condition factor from July onwards, but was independent of fork length. Food deprivation in either early winter (November-December, 8.2-4.1°C), late winter (February-April, 0.7-4.0°C), or both early and late winter (double deprived) reduced the female grilse rate (p < 0.01) to 4, 7, and 2% versus 18% in the control, whereas male grilse rate was reduced by a lesser degree (p > 0.05), 43, 39, and 33% versus 44% in the control. Mean condition factor among both maturing and immature fish decreased by a similar degree due to food deprivation but from spring onwards increased by a faster rate among incipient grilse. In a large experiment in four sea cages (each n = 3885 fish) using similar food deprivation treatments, the reduction in grilse rate was statistically significant in both sexes: among males, 28-36 versus 43% in the control; among females, 3-4 versus 6% in the control.

CONTRAFREELOADING IN STARLINGS: TESTING THE INFORMATION HYPOTHESIS

AbstractContrafreeloading (CFL) behaviour, in which animals forage persistently in patches that require effort to exploit when patches containing ad lib. food are easily available, seems to contradict the predictions of optimal foraging theory. However, it has been proposed that contrafreeloaders are in fact exploiting a hidden resource, namely information about patches that may be useful in future foraging attempts. We performed two experiments on starlings Sturnus vulgaris to test this hypothesis by determining the circumstances in which CFL occurs and assessing whether any useful information is acquired by animals performing the behaviour. In accordance with previous results we found that CFL is reduced when foragers are previously deprived of food and also when there are means of gathering information aside from sampling (namely when patches that require effort to exploit can be visually inspected). We also found that useful information is acquired by birds that perform CFL, in that when subsequently tested in extinction with the best patch removed they reliably chose the patch that had been the second best. These results are consistent with the information gain hypothesis. However, birds with low levels of CFL did not perform discernably worse in this test of patch knowledge and experimental reductions in CFL achieved through deprivation treatments did not produce apparent reductions in useful information possessed.

Effects of the fructose analog, 2,5-anhydro-D-mannitol, on food intake and estrous cyclicity in Syrian hamsters.

Hyperphagia and anovulation are both triggered by prior food deprivation or other treatments that decrease intracellular availability of metabolic fuels in most species studied. Syrian hamsters fail to show compensatory hyperphagia, but do show anestrus in response to these energetic challenges. In the present experiments, we examined food intake, plasma glucose levels, and estrous cyclicity in Syrian hamsters in response to 2,5-anhydro-D-mannitol (2,5-AM), a fructose analog that is thought to trigger eating in rats by depleting intracellular levels of ATP. In experiment 1, female estrous cycling hamsters were treated with 100, 200, 400, or 800 mg/kg 2,5-AM or the vehicle by intraperitoneal injection. Food intake was measured 1, 2, 4, 8, and 24 h after treatment. There were no statistically significant increases in food intake in response to any dose of 2,5-AM. In experiment 2, blood samples were drawn at 0, 1, 3, 5, 7, and 25 h after hamsters were treated with 0 or 400 mg/kg 2,5-AM. 2,5-AM treatment resulted in a mild but significant decrease in plasma glucose levels similar to those seen in 2,5-AM-treated rats, suggesting that 2,5-AM has similar effects on fuel metabolism in rats and hamsters. In experiment 3, hamsters received 2,5-AM, 2,5-AM plus the fatty acid oxidation inhibitor methyl palmoxirate, or vehicle every 6 h over the first 48 h of the estrous cycle and were tested for indexes of estrous cyclicity at the end of the cycle. All hamsters showed normal estrous cycles, regardless of treatment. If 2,5-AM has similar metabolic consequences in rats and hamsters, the present results suggest that decreased intracellular levels of ATP and mild hypoglycemia do not increase food intake or inhibit estrous cyclicity in Syrian hamsters.

Effects of continuous light on experimental refractive errors in chicks

SummaryIt is possible to induce ametropias in young chicks either by depriving the developing eye of clear form vision with a translucent goggle or by defocusing the retinal image with convex or concave lenses. The refractive properties of the developing chick eye are also altered by raising young birds in a continuous light environment. The effects of superimposing form deprivation or defocus treatments on chicks raised in continuous light are unclear. Newly hatched (n = 31) chicks were raised for 2 weeks under continuous light while wearing either translucent goggles or + 10 or − 10 diopter (D) lenses over one eye. Refractive states, corneal curvature and intraocular dimensions were measured periodically by retinoscopy, keratometry and A‐scan ultrasound. The birds were sacrificed after 2 weeks and the eyes removed and measured with calipers. Under continuous light, all eyes treated with translucent goggle and − 10D lens developed moderate myopia (− 2.6 ± 0.5 D and − 1.4 ± 0.3 D, respectively) by day 4. The eyes treated with a + 10 D lens developed moderate hyperopia (+ 4.8 ± 0.5 D) at day 4. Corneal curvatures of all treated eyes were slightly, but significantly, larger than contralateral control eyes by day 4. After 2 weeks of goggle or lens application, all the treated eyes were hyperopic due to corneal flattening. But the eyes treated with a goggle or a − 10 D lens still showed relative myopia compared to the fellow eyes (treated minus untreated = − 3.8 ± 0.4 D and − 2.8 ± 0.4 D, respectively), and the eyes treated with a + 10 D lens showed more hyperopia than fellow eyes (treated minus untreated = + 5.1 ± 0.6 D). Compared with the control eyes, the axial length (mainly vitreous chamber depth) was slightly, but significantly, increased in the eyes treated with a goggle or a − 10 D lens, and the axial length decreased slightly in the eyes treated with + 10 D lens. The results suggest that form deprivation and retinal defocus (induced by ± 10 D lenses) could still induce experimental refractive errors (myopia and hyperopia) in chicks kept under continuous light, but the effects of form deprivation and retinal defocus were partially suppressed by continuous light.

Effects of continuous light on experimental refractive errors in chicks

It is possible to induce ametropias in young chicks either by depriving the developing eye of clear form vision with a translucent goggle or by defocusing the retinal image with convex or concave lenses. The refractive properties of the developing chick eye are also altered by raising young birds in a continuous light environment. The effects of superimposing form deprivation or defocus treatments on chicks raised in continuous light are unclear. Newly hatched (n = 31) chicks were raised for 2 weeks under continuous light while wearing either translucent goggles or + 10 or − 10 diopter (D) lenses over one eye. Refractive states, corneal curvature and intraocular dimensions were measured periodically by retinoscopy, keratometry and A-scan ultrasound. The birds were sacrificed after 2 weeks and the eyes removed and measured with calipers. Under continuous light, all eyes treated with translucent goggle and − 10D lens developed moderate myopia (−2.6 ± 0.5 D and − 1.4 ± 0.3D, respectively) by day 4. The eyes treated with a + 10 D lens developed moderate hyperopia (+ 4.8 ± 0.5 D) at day 4. Corneal curvatures of all treated eyes were slightly, but significantly, larger than contralateral control eyes by day 4. After 2 weeks of goggle or lens application, all the treated eyes were hyperopic due to corneal flattening. But the eyes treated with a goggle or a − 10 D lens still showed relative myopia compared to the fellow eyes (treated minus untreated = −3.8 ± 0.4D and −2.8 ± 0.4D, respectively), and the eyes treated with a + 10 D lens showed more hyperopia than fellow eyes (treated minus untreated = +5.1 ± 0.6D). Compared with the control eyes, the axial length (mainly vitreous chamber depth) was slightly, but significantly, increased in the eyes treated with a goggle or a −10D lens, and the axial length decreased slightly in the eyes treated with +10D lens. The results suggest that form deprivation and retinal defocus (induced by ±10D lenses) could still induce experimental refractive errors (myopia and hyperopia) in chicks kept under continuous light, but the effects of form deprivation and retinal defocus were partially suppressed by continuous light.

Separating food and water deprivation in locusts: effects on the patterns of consumption, locomotion and growth

Abstract. In a factorial experiment, fifth‐instar Locusta migratoria (L.) (Orthoptera: Acrididae) were given either dry food (lyophilized grass) and drinking water, food only, water only, or neither food nor water.Food consumption and insect weight were measured daily, and the behaviour of each locust was recorded for 5 h on each of four consecutive days and for 2.5 h on the fifth.Consumption declined progressively in locusts given food only, and those given water only were not observed to drink after the first day of food deprivation.The decline in food consumption on the first day was accounted for by a decrease in the average duration of feeds, which remained constant thereafter.The further decline in consumption over subsequent days was due to a progressive decline in the number of feeds.Although food availability did not slow weight loss relative to locusts given neither food nor water, the availability of water without food did.The proportion of time locomoting increased in all deprivation treatments, but the pattern of change across the five observation days differed markedly between treatments.Locusts given food but no water increased locomotion from 20% of the time budget (the value for controls) to 30% on the first day of deprivation, and by the second day had reached a plateau of approximately 65%.which was maintained until the experiment was terminated on day 5.In contrast, locusts given water but no food approached the 65% level of locomotion on the first day, which was stutistically greater than the 55% observed in those deprived of both food and water.This increase was due both to an increase in the number of locomotion bouts initiated and an increase in the average duration of locomotion bouts.On the second and third days, all deprivation treatments maintained locomotion at around 65%.By day 4, locomotion had decreased to approximately 15% in locusts deprived of both food and water, but not in those deprived of food only or water only.Unlike those given only food, locusts given only water showed a reduction in locomotion of c. 15% on the fifth day.

Amitriptyline in combination with repeated late sleep deprivation versus amitriptyline alone in major depression. A randomised study

Only few systematic studies are available on the status of sleep deprivation therapy in the overall treatment regimen of depressive patients. 51 patients suffering from a major depressive episode (ICD-10) were randomly allocated to 4 weeks' treatment with amitriptyline (150 mg/day) or to a combination of amitriptyline with six partial-sleep-deprivation treatments late in the night (at 4–5-day intervals). According to observer rating (Hamilton Rating Scale for Depression, 21 — and 10-item version), a highly significant amelioration was recorded in both groups until the 14th day of treatment. A further improvement occurred, however, only in those patients treated with both antidepressants and sleep deprivation. Hence the response rate (≥ 50% HAMD reduction) after 4 weeks' treatment was distinctly more favourable in this group than in those patients under pharmacotherapy alone. The superiority of the combined therapy cannot be confirmed statistically by self-rating (Befindlichkeitsskala: von Zerssen; Visual Analogue Mood Scale). The immediate antidepressive effect of sleep deprivation diminished in the course of the sleep deprivation series. The response to the first sleep deprivation was a predictor neither for the response to further sleep deprivation treatments nor for the overall treatment outcome.

Sensitivity of Yield and Fruit Quality of French Prune to Water Deprivation at Different Fruit Growth Stages

The sensitivity of French prune (Prunus domestica L. syn. `Petite d'Agen') to water deprivation at various fruit growth stages was studied over 3 years in a drip-irrigated orchard. The soil was a poorly drained Rocklin fine sandy loam with a hardpan that varied from 4.75 to I m from the surface at the northern end of the orchard (shallow soil condition) to no hardpan apparent to 2 m below the surface at the southern end of the orchard (deep soil condition). Water deprivation during a) the first exponential phase of fruit growth or stage I, b) lag phase of fruit growth or stage II, c) first half of stage II, d) second half of stage II, e) second exponential fruit growth phase or stage III, and f) postharvest was compared to a fully watered control. Water deprivation caused the most severe reduction in tree water status when it was imposed over longer periods of time and during periods of high evaporative demand and also had mm-e severe effects under shallow soil conditions. Compared to the control treatment, deprivation during all of stage II (the most severe deprivation treatment) was associated with increased Ilowering, reduced fruit hydration ratio, and smaller fruit size under all soil conditions. Under deep soil conditions, deprivation during all of stage II resulted in increased return bloom, which was reflected in higher fruit loads and dry t-ha-' fruit yield. However, under shallow soil conditions, even though return bloom was increased with this treatment, fruit loads and dry t·ha-1 fruit yields were the lowest of all treatments. These differences in treatment effects in shallow vs. deep soil conditions were most likely the result of increased fruit drop, which occurred under shallow soil conditions as a result of rapid onset and increased severity ofstress. Treatments that had parallel effects in shallow and deep soil conditions resulted in statistically significant overall treatment effects, while those that had opposing effects in shallow vs. deep soil conditions did not show significant overall treatment effects. Substantial alternate hearing occurred, and, in general, dry fruit yields above ≈9 dry t·ha-1 resulted in a decrease in fruit load the following year, while loads below this value showed a subsequent increase. Based on a separate estimate of the theoretically stable value for each treatment, all deprivation treatments resulted in a higher sustainable fruit load compared to the fully irrigated control. This suggests that, for the purpose of prune fruit production, there may be an optimal level of tree water stress.

A clinical trial of sleep deprivation in combination with antidepressant medication

The literature suggests that sleep deprivation can potentiate the effect of antidepressant medication in depressed patients. However, the clinical efficacy of sleep deprivation has not been demonstrated definitely, in part because it is difficult to design an adequate control condition. We conducted a trial of sleep deprivation in 26 depressed patients who remained symptomatic despite 3 months of treatment with antidepressant medication. Since the literature indicates that early sleep deprivation (ESD), carried out in the first half of the night, is a less effective antidepressant than late sleep deprivation (LSD), carried out in the second half of the night, we designed a study that attempt to use ESD as a control condition for LSD. Patients were randomly assigned to ESD or LSD, received a total of 4 nights of sleep deprivation over 2 weeks, and were followed in clinic for the 3 subsequent weeks. ESD proved to be as effective an antidepressant as LSD, with the overall sample showing a mild, but statistically significant, response. There was a significant correlation between patients' acute response at the time of the first course of sleep deprivation treatments and their improvement over the course of the study. There were significant changes in plasma levels of thyroid stimulating hormone, free triidothyronine, prolactin, and cortisol measured at 8 a.m. before and after sleep deprivation, and in the followup period, but there were no significant correlations between changes in hormonal levels and either acute or chronic response to sleep deprivation.

Insulin and Glucose-dependent Regulation of the Glucose Transport System in the Rat L6 Skeletal Muscle Cell Line

Differentiated rat L6 skeletal muscle cell cultures maintained in glucose-deficient medium containing 25 mM xylose displayed a rapid, reversible, time- and concentration-dependent 3-5-fold increase in glucose transport activity. Glucose deprivation in the continuous presence of insulin (24 h) resulted in an overall 9-10-fold stimulation of glucose transport activity. In contrast, acute (30 min) and chronic (24 h) insulin treatment of L6 cells maintained in high glucose (25 mM)-containing medium resulted in a 1.5- and 4-fold induction of glucose transport activity, respectively. Acute glucose deprivation and/or insulin treatment had no significant effect on the total amount of glucose transporter protein, whereas the long-term insulin- and glucose-dependent regulation of glucose transport activity directly correlated with an increase in the cellular expression of the glucose transporter protein. In situ hybridization of the L6 cells demonstrated a 3-, 4-, and 6-fold increase in glucose transporter mRNA induced by glucose deprivation, insulin, and glucose deprivation plus insulin treatments, respectively. Similarly, Northern blot analysis of total RNA isolated from glucose-deprived, insulin, and glucose-deprived plus insulin-treated cells resulted in a 4-, 3-, and 9-fold induction of glucose transporter mRNA, respectively. The continuous presence of insulin in the medium, either in the presence or absence of glucose, resulted in a transient alteration of the glucose transporter mRNA. The relative amount of the glucose transporter mRNA was maximally increased at 6-12 h which subsequently returned to the basal steady-state level within 48 h. These data demonstrate a role for insulin and glucose in the overall regulation of glucose transporter gene expression which may account for the alteration of glucose transporter activity of muscle tissue observed in pathophysiological states such as type II diabetes mellitus.

Nitrate Nutrition of Grasses from Steady-State Supplies in Flowing Solution Culture following Nitrate Deprivation and/or Defoliation

Two Lolium genotypes, i.e. Lolium perenne cv. S23 and a L. perenne × L. multiflorum hybrid cv. Augusta were, in one treatment, grown in flowing solution culture with a maintained supply of NO3- at 10 mmol m−3 NO3- throughout. In another treatment, the plants were deprived of NO3- for 11 d, NO3- was then re-supplied and both control and N-deprived plants were either defoliated or left entire. Effects of the stresses imposed by N deprivation or defoliation on subsequent net uptake of NO3-⁠, shoot and root growth and their interactions were examined. There were no major differences in the behaviour of the two genotypes throughout. The removal of NO3 supply did not alter total dry matter production during the 11 d period of deprivation but the rate of root growth accelerated markedly. There was little effect of N deprivation on the specific growth rates of the recovering defoliated shoots. Cumulative net uptake of NO3- closely paralleled the pattern of growth and there were obvious and marked effects of both N deprivation and defoliation. Effects on NO3- uptake were more distinctly demonstrated when uptake was expressed on a per unit root or shoot basis, i.e. specific unit absorption rates (SNO3). In the control plants with sustained NO3- supply, there was a progressive decline with time in SNO3, in spite of an increasing shoot: root ratio. After both N deprivation and defoliation treatments there was a rapid initial increase in SNO3, followed by an oscillatory cycle of increasing and decreasing rates with a 10–11 d period. The relationships between growth and NO3- uptake were complex and did not conform to a previously predicted linear relationship between SNO3, and the ratio total fresh plant weight: root fresh weight. The results are discussed in relation to the possible mechanisms involved. It is suggested that the oscillations in unit absorption rate indicated that the roots of N-deprived or defoliated plants retained a high capacity for absorption immediately after re-supply or defoliation and that the stressed plants were unable to assimilate or utilize NO3- taken up; net uptake then decreased through a shift in favour of efflux over influx until the influx mechanism was able to dominate and the pattern was then repeated.

Rat strain comparisons on drug and sleep sensitive behaviors

Rat swimming behaviors have been productive in both sleep research and neuropharmacology. In this report, both of these areas are addressed in the context of inbred strain effects. Thrity-two rats from three stocks were tested in a seven day, repeated measures design. Each rat swam for 5 min each day in shallow 25°C water. There were significant differences between inbred stocks on two measures which can be related to both REM sleep deprivation and adrenergic drug effects. Nonsignificant strain differences were found on two other behaviors which also lack significance under REM sleep deprivation and atropine sulfate treatments. It is concluded that there may be differential stres affecting the treatmentsensitive and the change-resistant behaviors.

Analysis of appetitive motivation in preweanling rats: Application of bromocryptine mesylate

Two experiments investigated discrimination learning with preweanling rats (Rattus norvegicus) following different experimental deprivation treatments. In Experiment 1, 10- to 11-day-old Sprague-Dawley rats were deprived for 24 h of either nutrients and maternal contact through placement in an incubator or only nutrients by placement in the nest of a bromocryptine mesylate-treated dam. Bromocryptine mesylate inhibits prolactin release and thereby prevents lactation with only minimal effect on maternal behaviors. After the deprivation period, pups were trained to perform a spatial discrimination for milk infusion into the oral cavity or for the opportunity to suckle the dry nipples of an anesthetized dam. The results revealed, irrespective of deprivation treatment, that pups failed to acquire a simple T-maze spatial discrimination for milk reward although they rapidly learned to approach and locate an anesthetized dam to suckle. Experiment 2 followed up with a different procedure. Results indicated that during bouts of suckling rat pups preferred an active, lactating dam letting down milk to an identical dam not letting down milk due to her pretreatment with bromocryptine mesylate. These results illustrate a constraint on learning which affects immature rats. The capability to learn on appetitively motivated spatial discrimination appears intricately tied to the context in which training occurs. Results are discussed according to how the organism's expectancy can mediate performance.