Effects of Lanthanum Chloride Administration in Prenatal Stage on One-Trial Passive Avoidance Learning in Chicks

Lanthanum cations (La 3+) are well known for their inhibitory actions on calcium channels. Prenatal lanthanum exposure may affect the development of embryo and alter the capacity for learning and memory in adults, and the one-trial passive avoidance learning paradigm with day-old chicks is an excellent model to study several mechanisms of memory formation. In the present study, we examined the effects of prenatal lanthanum chloride exposure on memory consolidation using one-trial passive avoidance learning task in day-old chicks. The data suggest that chicks injected with lanthanum chloride (2 mg/kg) daily from E9 to E16 had significantly impaired long-term memory at 120 min after training (p < 0.05) but not the chicks injected with lanthanum chloride (0.1 mg/kg) daily from E9 to E16.     

Visual lateralization and development of spatial and social spacing behaviour of chicks (Gallus gallus domesticus)

We investigated whether the development of spatial behaviour of the domestic chicken is influenced by light exposure of the embryo, as is known to be the case for some other lateralized visual functions. Ninety-six chicks were incubated in the dark or exposed to light during the final days of incubation. Half of the chicks in each group had the experience of moving behind opaque screens from 10 to 12 days of age. The other half were given transparent screens as a control. Chicks were tested in a detour test and a rotated floor test and their dispersal in groups was observed in larger pens. In the rotated floor test, chicks that had had experience with opaque screens used distal cues significantly more often than chicks that had experience with transparent screens (P = 0.042), regardless of whether they had been exposed to light before hatching or incubated in the dark. There were no significant differences between treatments in the detour test or in the dispersal behaviour. Hence, visual lateralization has no influence on the development of the spatial behaviour that we tested, whereas the occlusion experience is quite specific and results in shifted attention to distal spatial cues.     

Effects of lanthanum on calcium-dependent phenomena in human red cells.

Lanthanum (0.25 mM) does not penetrate into fresh or Mg2+-depleted cells, whereas it does into ATP-depleted or ATP + 2,3-diphosphoglycerate-depleted cells, into cells containing more than 3 mM calcium, or cells stored for more than 4 weeks in acid/citrate/dextrose solution. In fresh cells loaded with calcium, extracellular lanthanum blocks the active Ca2+-efflux completely and inhibits (Ca2+ + Mg2+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity to about 50%. In Mg2+-depleted cells Ca2+-Ca2+ exchange is inhibited by lanthanum. Ca2+-leak is unaffected by lanthanum up to 0.25 mM concentration; higher lanthanum concentrations reduce leak rate. In NaCl medium Ca2+-leak +/ S.D. amounts to 0.28 +/ 0.08 mumol/1 of cells per min, whereas in KC1 medium to 0.15 +/ 0.04 mumol/1 of cells per min at 2.5 mM [Ca2+]e and 0.25 mM [La3+]e pH 7.1. Lanthanum inhibits Ca2+-dependent rapid K+ transport in ATP-depleted and propranolol-treated red cells, i.e. whenever intracellular calcium is below a critical level. The inhibition of the rapid K+ transport can be attributed to protein-lanthanum interactions on the cell surface, since lanthanum is effectively detached from the membrane lipids by propranolol. Lanthanum at 0.2--0.25 mM concentration has no direct effect on the morphology of red cells. The shape regeneration of Ca2+-loaded cells, however, is blocked by lanthanum owing to Ca2+-pump inhibition. Using lanthanum the transition in cell shape can be quantitatively correlated to intracellular Ca2+ concentrations.     

Interaction of lanthanum chloride with human erythrocyte membrane in relation to acetylcholinesterase activity

Lanthanum chloride (1 mM) inhibits the activity of acetylcholinesterasein vitro in the human erythrocyte membrane. Lineweaver-Burk analysis indicates that lanthanum chloride induced inhibition of acetylcholinesterase activity is competitive in nature. The Arrhenius plot shows that the transition temperature of erythrocyte membrane-bound acetylcholinesterase is significantly reduced in the presence of lanthanum chloride. These results suggest that lanthanum chloride increases the fluidity of the erythrocyte membrane and this may be a cause of inhibition of membrane-bound acetylcholinesterase activity.     

Enhancing Effects of Chronic Lithium Treatment on Detour Learning in Chicks

Lithium is the first line of therapeutic drugs used to treat both mania and depression in bipolar disorder.Although a body of research suggests that lithium acts as a cognitive enhancer, other animal studies suggest that lithium induces cognitive deficits. Comparatively, the effects of lithium on cognitive behaviour in these studies are inconsistent and contradictory. Further investigations in different species of animals and behavioural tasks are important to evaluate the possibility that lithium may act as a cognitive enhancer. In the present study, the chicks were treated intraperitoneally with lithium chloride (120 mg/kg), and the effects of chronic lithium treatment on chick cognitive behaviour were examined using a detour learning task.Additionally, the effects of chronic lithium treatment on BDNF messenger RNA (mRNA) expression were measured in RTPCR. We found that chronic lithium treatment(120 mg/kg) had no effect on spontaneous motor activity or weight gain of the chicks and that the chicks had a general healthy appearance, while chronic lithium treatment significantly promoted the response latency of detour learning and BDNF mRNA expression. These results suggest that chronic lithium treatment may improve cognitive function.     

Paracellular pathway in the shell epithelium of Anodonta cygnea

Ultrastructural study of cell-cell connections in the outer mantle epithelium (OME) on high-pressure-frozen specimens revealed zonula adherens, septate junctions and gap junctions in Anodonta cygnea. In order to evaluate the permeability of the paracellular pathway, the OME was incubated under gradients of lanthanum and calcium. After lanthanum incubation (4 mM) from the basal side, the septate junctions were penetrated completely by this tracer. When applied from the apical side, lanthanum deposits were located similarly over the entire length of the septate junctions up to the first dilatations of the intercellular space. Calcium deposits were also present in paracellular areas only when OME had been incubated simultaneously with calcium (6 mM) and lanthanum (4 mM) gradients. Lanthanum and calcium deposits were detected with ESI (Electron Spectroscopic Imaging) and identified with EELS (Electron Energy Loss Spectroscopy). On the other hand, electrophysiological observations showed a 48% reduction of conductance when the OME was bathed on both sides with solutions containing lanthanum (4 mM) and calcium (6 mM), compared to bathing with lanthanum-free solution (control). The conductance reduction was 52% when calcium was removed from the control solution. Supported by morphological and physiological evidence, it appears that, under in vivo conditions, calcium ions may diffuse paracellularly from the haemolymph towards the extrapallial fluid and vice-versa across the septate junctions in the OME of A. cygnea. Permeability of the septate junctions depended proportionally on the calcium concentration in fluids.     

Effects of lanthanum on calcium-dependent phenomena in human red cells

Lanthanum (0.25 mM) does not penetrate into fresh or Mg²⁺-depleted cells, whereas it does into ATP-depleted or $\text{ATP + 2,3-diphosphoglycerate-depleted cells}$, into cells containing more than 3 mM calcium, or cells stored for more than 4 weeks in acid/citrate/dextrose solution. In fresh cells loaded with calcium, extracellular lanthanum blocks the active Ca²⁺-efflux completely and inhibits $\text{(Ca}{}^{\mathrm{2+}}\text{+ Mg}{}^{\mathrm{2+}}\text{)-ATPase}$ (ATP phosphohydrolase, EC 3.6.1.3) activity to about 50%. In Mg²⁺-depleted cells Ca²⁺-Ca²⁺ exchange is inhibited by lanthanum. Ca²⁺-leak is unaffected by lanthanum up to 0.25 mM concentration; higher lanthanum concentrations reduce leak rate. In NaCl medium Ca²⁺-leak ± S.D. amounts to $\text{0.28 ± 0.08 μ}\text{mol/l}$ of cells per min, whereas in KCl medium to $\text{0.15 ± 0.04 μ}\text{mol/l}$ of cells per min at 2.5 mM [Ca²⁺]_e and 0.25 mM [La³⁺]_e pH 7.1.Lanthanum inhibits Ca²⁺-dependent rapid K⁺ transport in ATP-depleted and propranolol-treated red cells, i.e. whenever intracellular calcium is below a critical level. The inhibition of the rapid K⁺ transport can be attributed to protein-lanthanum interactions on the cell surface, since lanthanum is effectively detached from the membrane lipids by propranolol.Lanthanum at 0.2–0.25 mM concentration has no direct effect on the morphology of red cells. The shape regeneration of Ca²⁺-loaded cells, however, is blocked by lanthanum owing to Ca²⁺-pump inhibition. Using lanthanum the transition in cell shape can be quantitatively correlated to intracellular Ca²⁺ concentrations.     

Influence of a mobile robot on the spatial behaviour of quail chicks

Quail chicks encountered an autonomous mobile robot during their early development. The robot incorporated a heat source that stimulated following of chicks. The spatial behaviour of grown-up chicks was tested in an exploration test and a detour test. Chicks that grew with the mobile robot exhibited better spatial abilities than chicks grown with a static heat source. We discuss these results in the perspective of animal-robot interaction and of the role of early spatial experience on the behavioural development.     

Detour behaviour in horses (<Emphasis Type="Italic">Equus caballus</Emphasis>)

The objective of this study was to investigate the ability of horses (Equus caballus) to detour around symmetric and asymmetric obstacles. Ten female Italian saddle horses were each used in three detour tasks. In the first task, the ability to detour around a symmetrical obstacle was evaluated; in the second and third tasks subjects were required to perform a detour around an asymmetrical obstacle with two different degrees of asymmetry. The direction chosen to move around the obstacle and time required to make the detour were recorded. The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles. The strategy used to perform the task varied between subjects. For five horses, lateralized behaviour was observed when detouring the obstacle; this was consistently in one direction (three on the left and two on the right). For these horses, no evidence of spatial learning or reasoning was found. The other five horses did not solve this task in a lateralized manner, and a trend towards decreasing lateralization was observed as asymmetry, and hence task difficulty, increased. These non-lateralized horses may have higher spatial reasoning abilities.     

The relationship between male sexual signals,cognitive performance,and mating success in stickleback fish

Cognitive ability varies dramatically among individuals, yet the manner in which this variation correlates with reproduction has rarely been investigated. Here, we ask (1) do male sexual signals reflect their cognitive ability, and (2) is cognitive ability associated with male mating success? Specifically, we presented threespine sticklebacks (Gasterosteus aculeatus ) with a detour‐reaching task to assess initial inhibitory control. Fish that performed better were those who solved the detour‐reaching task, solved it faster, and required fewer attempts to solve. We then reexamined males’ performance on this task over several days to assess learning ability in this context. We next measured sexual signals (coloration, nest area, and courtship vigor) and asked whether they reveal information about these male cognitive abilities. Finally, we examined whether success at attracting a female is associated with male cognition. After controlling for the strong effect of neophobia, we found that no measured sexual signals were associated with initial inhibitory control. Sexual signals were also not associated with change in performance on the detour‐reaching task over time (learning). However, females preferred mating with males who had better initial inhibitory control. We speculate that inhibitory control is a critical trait for male sticklebacks. In this system, males perform all parental care, but must avoid eating their own fry which closely resemble their prey items. Therefore, males with better inhibitory control may be more likely to successfully raise their offspring to independence. Our research adds to a growing list of mating systems and taxa in which cognition is important for measures related to fitness.     

Uptake and intracellular distribution of lanthanum

The present investigation of the cellular distribution of lanthanum was undertaken in order to control the validity of the "Lanthanum method" used for the study of the cell calcium compartments. The presence of lanthanum was evaluated in the isolated guinea-pig heart and its subcellular fractions perfused with a lanthanum-containing Tyrode solution. Lanthanum was determined by instrumental neutron activation analysis. Under the adopted experimental conditions (30-min incubation in the presence of 12.5 microM lanthanum), lanthanum is carried across the cell membrane and is taken up by subcellular organelles. These results confirm the limited validity of investigations based on of the "Lanthanum method".     

Amino acid transport in the rat exocrine pancreas

Summary The two calcium antagonistic agents lanthanum and tetracaine cause severe disturbances in the secretory process of the exocrine pancreas, including inhibition of the rate of protein synthesis and exocytosis. The former effect resulted mainly from the inhibition of amino acid transport. Lanthanum in a concentration up to 1 mM inhibited transport of different species of amino acids in an unspecific way whereas tetracaine interfered specifically with the Na⁺-dependent transport system for neutral amino acids (¹⁴C--amino-isobutyric acid). Na⁺-independent transport of neutral amino acids (³H-leucine) was not affected. Transport inhibition was correlated to the activity of the Na⁺, K⁺-ATPase system which was measured in isolated plasma membrane fractions. At higher concentrations (5–10 mM) some uptake of lanthanum into the cells by limited endocytosis was observed. At lower concentrations lanthanum seemed to bind exclusively to certain components of the plasma membrane, mainly at the lateral and basal cell surface. Even at a concentration of 5–10 mM, no binding to the apical surface occurred. Similarly, no binding of lanthanum was observed to the limiting membrane of isolated zymogen granules, while mitochondria, contained in the same fraction, showed considerable binding affinity. The action of lanthanum and tetracaine on membrane carrier systems did not affect the interior organization of the plasma membrane. Particle density and distribution in freeze-fracture replicas as well as the submembrane microfilamentous-microtubular system and the junctional elements remained unaffected.Supported by a grant from the Deutsche Forschungsgemeinschaft (Ke 113/10). The expert technical assistance of Miss Helga Hollerbach and Miss Hiltraud Hosser and the editorial help of Mrs. Gisela Lesch is gratefully acknowledged     

Factors Influencing the Formation and Stability of Filled Hydrogel Particles Fabricated by Protein/Polysaccharide Phase Separation and Enzymatic Cross-Linking

Filled hydrogel particles can be used to encapsulate, protect, and deliver lipophilic components. In this study, we investigated the influence of preparation conditions on the size of filled hydrogel particles created using biopolymer phase separation and enzymatic cross-linking. We then investigated the stability of these particles to external stresses: pH (pH 2–8); heat (40°–90 °C, 20 min); sodium chloride (0–500 mM); and calcium chloride (0–8 mM). Filled hydrogel particles were fabricated as follows: (i) high methoxy pectin, sodium caseinate, and caseinate-coated lipid droplets were mixed at pH 7 under conditions where phase separation due to thermodynamic incompatibility occurred; (ii) this mixture was acidified (pH 5) to induce adsorption of anionic pectin molecules around lipid-filled caseinate-rich particles; (iii) the caseinate within the particles was enzymatically cross-linked using transglutaminase. Three mixing conditions (0, 100, and 1,000 rpm) were tested during particle acidification. Particle size measurements indicated that larger particles were formed at 0 and 100 rpm than at 1,000 rpm. Under high pH conditions (pH 6–8), particles cross-linked with transglutaminase remained intact while control particles (not cross-linked) disintegrated. The addition of calcium to both control and cross-linked particles resulted in system gelation above 4 mM calcium chloride. Control and cross-linked particles remained stable to heating and to the addition of sodium chloride. Results from this study demonstrate the versatility and robustness of this delivery system for lipophilic bioactives.     

<Emphasis Type="SmallCaps">l</Emphasis>-Proline is a sedative regulator of acute stress in the brain of neonatal chicks

The purpose of the present study was to clarify the central nervous system function of amino acids during acute stress. In Experiment 1, changes in free amino acid pattern were investigated in the brain of neonatal chicks exposed to either restraint with isolation-induced or fasting stress. l-Proline and l-arginine were decreased in the telencephalon and diencephalon under any stress. Since the central nervous system functions of l-arginine during the stress response has recently been reported, in Experiment 2, the effect of intracerebroventricular injection of l-proline (0.5, 1.0, 2.0 μmol) during isolation-induced stress was investigated. l-Proline induced sedative and hypnotic effects in a dose-dependent manner. It is suggested that l-proline may have an important role to attenuate the stress response in the central nervous system of chicks.     

The effects of ionic lanthanum and hypertonic physiological salines on the nervous systems of larval and adult stick insects.

The effects of the electron-opaque tracer ionic lanthanum in various concentrations and of hyperosmotic physiological salines on the nervous system of the stick insect, Carausius morosus, have been studied. Examination of the experimentally treated tissues revealed that the diffusion barrier to the exogenous tracer was maintained in all cases in the adult central and peripheral nervous systems, but not in the hatchling. When hatchling nervous tissues were incubated in 50 mM ionic lanthanum in phyerosmotic physiological saline, the tracer readily infiltrated all the extracellular spaces between axons and glia of all components of the nervous system examined. No difference was noted in this regard between fed and unfed hatchlings, Further, in all cases examined of adults and hatchlings, lanthanum readily surrounded those neurosecretory axons which are found in the neutral lamella, or extracellular nerve sheath, of the insect. The possible meanings of these variations in hatchling and adult nervous systems and in the accessibility of different elements of the nervous system to exogenous ionic lanthanum are discussed.     

The effects of cations on the activity of the gypsy moth (Lepidoptera: Lymantriidae) nuclear polyhedrosis virus

Fourteen cations were tested at a 1% concentration (wt:wt), as chlorides, for their effects on the biological activity of the gypsy moth, Lymantria dispar (L.), nuclear polyhedrosis virus (LdMNPV). Cupric chloride was toxic to gypsy moth larvae. Ferrous and ferric chloride were inhibitory to larval growth and development as well as to virus activity. Strontium chloride was inhibitory to virus activity but had no apparent effects on gypsy moth larvae. Six cations had little or no effect on virus activity (i.e., calcium, lanthanum, magnesium, nickel, potassium, sodium), whereas four cations (i.e., cobalt, manganese, ruthenium, zinc) acted as viral enhancers, as indicated by reductions in LC50s.     

Development of spatial memory in occlusion-experienced domestic chicks

At around day 11 of life, domestic chicks show a tendency to move out of sight of their mother before returning and regaining social and visual contact. We conducted a series of experiments to investigate the role of this voluntary ‘out-of-sight’ behaviour on the development of spatial memory in young chicks. We compared the behaviour of chicks that were reared in environments that provided opportunities to move out of sight of an imprinting stimulus (occlusion-experienced chicks) with the behaviour of chicks that were given minimal occlusion experience (controls). As in natural conditions, out-of-sight behaviour peaked on day 11. When chicks were released into larger pens at 14 days of age, occlusion-experienced chicks walked more than control chicks, but otherwise showed similar degrees of dispersal. Occlusion-experienced chicks tended to show better (although not significant, P=0.09) retrieval of a visually displaced imprinting stimulus than control chicks. Time spent out of sight in the rearing pens was negatively related to the number of orientation errors in a detour test. Occlusion-experienced chicks also tended to make fewer orientation errors in the first trial (P=0.07) and in subsequent trials (P=0.05). In contrast, experimentally manipulating the amount of time that chicks were out of sight of an imprinting stimulus (by confining the chicks) had no effect on their performance in displacement or detour tests. The results presented here suggest that active experience of occlusion around day 11 improved egocentric orientation towards an out-of-sight goal, supporting the hypothesis that enrichment-induced behavioural changes are dependent on the interaction with objects.     

Permeability of the haemolymph-neural interface in the terrestrial snail Megalobulimus abbreviatus (Gastropoda, Pulmonata): an ultrastructural approach

The aim of this study was to investigate the ultrastructure of the interface zone between the nervous tissue and the connective vascular sheath that surround the central ganglia of the terrestrial snail of Megalobulimus abbreviatus and test its permeability using lanthanum as an electron dense tracer. To this purpose, ganglia from a group of snails were fixed by immersion in a 2% colloidal lanthanum solution, and a second group of animals was injected in the foot with either a 2%, 10% or 20% lanthanum nitrate solution and then sacrificed 2 or 24 h after injection. Ganglia from both groups were processed for transmission electron microscopy. The vascular endothelium, connective tissue and basal lamina of variable thickness that ensheathe the nervous tissue and glial cells of the nervous tissue constitute the interface zone between the haemolymph and the neurones. The injected lanthanum reached the connective tissue of the perineural capsule; however, it did not permeate into the nervous tissue because the basal lamina interposed between both tissues interrupted this passage. Moreover, the ganglia fixed with colloidal lanthanum showed electron dense precipitates between the glial processes in the area adjacent to the basal lamina. It can be concluded from these findings that, of the different components of the haemolymph-neuronal interface, only the basal lamina, between the perineural capsule and the nervous tissue, limits the traffic of substances to and from the central nervous system of this snail.     

The effect of fetal calf serum on intracellular calcium in GH3 cells

We have investigated the mechanism of action of fetal calf serum (FCS) on GH3 pituitary tumour cells by measuring intracellular free calcium levels. On the addition of FCS (1%) there was a transient increase in intracellular Ca2+ levels which was attenuated in conditions of reduced extracellular calcium concentrations. The Ca2+ response was abolished by the prior addition of lanthanum chloride (1mM). In contrast, the elevation of cytosolic calcium levels by TRH (100nM), an agonist which causes the mobilisation of calcium from the endoplasmic reticulum, was attenuated but not abolished by lanthanum chloride (1mM). We suggest that FCS (1%) causes the release of calcium from the plasma membrane and the influx of calcium from the extracellular milieu, but does not mobilise calcium from the endoplasmic reticulum.