Sexual differences in the expression of copper deficiency in rats

The present investigation was undertaken to establish whether the severity of copper deficiency in rats fed diets containing fructose is affected by the presence and type of endogenous sex hormones. Intact and castrated male rats and intact and ovariectomized females were fed from weaning a copper-deficient diet (0.6 ppm) containing 62% fructose for 8 weeks. Regardless of castration, male rats were anemic, exhibited heart hypertrophy, and died of the deficiency. However, castration ameliorated the anemia and delayed the mortality. In contrast, none of the females died of the deficiency. It is suggested that in addition to the sex of the animal, levels of testosterone in the male may also play a role in the severity of copper deficiency.     

Sexual asymmetry in hermaphroditic plants

Populations of hermaphroditic plants show variation in ovule and pollen production, so that the implicit assumption that hermaphrodite individuals function half as male and half as female is not valid. Such variation in gamete production results in sexual asymmetry, defined as nonconstant ratios of pollen to ovule production among plants of a population. This article reviews (1) some of the considerable amount of recent evidence for sexual asymmetry and non-equal malelfemale sex functioning in hermaphroditic seed plants, and (2) some models of asymmetry and sex functioning, with emphasis on their biological and evolutionary relevance.     

Androgens exacerbate motor asymmetry in male rats with unilateral 6-hydroxydopamine lesion

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopamine neuron loss in the nigrostriatal pathway that shows greater incidence in men than women. The mechanisms underlying this gender bias remain elusive, although one possibility is that androgens may increase dopamine neuronal vulnerability to oxidative stress. Motor impairment can be modeled in rats receiving a unilateral injection of 6-hydroxydopamine (6-OHDA), a neurotoxin producing nigrostriatal degeneration. To investigate the role of androgens in PD, we compared young (2 months) and aged (24 months) male rats receiving gonadectomy (GDX) and their corresponding intact controls. One month after GDX, rats were unilaterally injected with 6-OHDA, and their motor impairment and asymmetry were assessed 2 weeks later using the cylinder test and the amphetamine-induced rotation test. Plasma samples were also collected to assess the concentration of testosterone and advanced oxidation protein products, a product of oxidative stress. GDX decreased lesion-induced asymmetry along with oxidative stress and increased amphetamine-induced rotations. These results show that GDX improves motor behaviors by decreasing motor asymmetry in 6-OHDA-treated rats, an effect that may be ascribed to increased release of striatal dopamine and decreased oxidative stress. Collectively, the data support the hypothesis that androgens may underlie the gender bias observed in PD.     

Androgens exacerbate motor asymmetry in male rats with unilateral 6-hydroxydopamine lesion

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopamine neuron loss in the nigrostriatal pathway that shows greater incidence in men than women. The mechanisms underlying this gender bias remain elusive, although one possibility is that androgens may increase dopamine neuronal vulnerability to oxidative stress. Motor impairment can be modeled in rats receiving a unilateral injection of 6-hydroxydopamine (6-OHDA), a neurotoxin producing nigrostriatal degeneration. To investigate the role of androgens in PD, we compared young (2 months) and aged (24 months) male rats receiving gonadectomy (GDX) and their corresponding intact controls. One month after GDX, rats were unilaterally injected with 6-OHDA, and their motor impairment and asymmetry were assessed 2 weeks later using the cylinder test and the amphetamine-induced rotation test. Plasma samples were also collected to assess the concentration of testosterone and advanced oxidation protein products, a product of oxidative stress. GDX decreased lesion-induced asymmetry along with oxidative stress and increased amphetamine-induced rotations. These results show that GDX improves motor behaviors by decreasing motor asymmetry in 6-OHDA-treated rats, an effect that may be ascribed to increased release of striatal dopamine and decreased oxidative stress. Collectively, the data support the hypothesis that androgens may underlie the gender bias observed in PD.     

Sexual differences in the activity of periventricular-hypophysial dopaminergic neurons in rats.

The activities of periventricular-hypophysial dopaminergic (DA) neurons were compared in male and female rats by measuring dopamine synthesis (accumulation of 3,4-dihydroxyphenylalanine [DOPA] after inhibition of L-aromatic amino acid decarboxylase) and metabolism (concentrations of 3,4-dihydroxyphenylacetic acid [DOPAC]) in terminals of these neurons in the intermediate lobe of the pituitary. For comparison, the synthesis and metabolism of dopamine in the neural lobe of the pituitary and median eminence were also determined. The concentrations of DOPAC and accumulation of DOPA were higher in females than in males in both the intermediate lobe and median eminence, revealing a sexual difference in the basal activity of periventricular-hypophysial and tuberoinfundibular DA neurons. In contrast, there were no differences between male and female rats in activity of DA neurons terminating in the neural lobe. One week following gonadectomy, DOPA accumulation in the median eminence was decreased in females and increased in males, but remained unchanged in the intermediate lobe. These results indicate that sexual differences in the activity of periventricular-hypophysial DA neurons terminating in the intermediate lobe are not dependent upon the presence of circulating gonadal steroids, and in this respect, these neurons differ from tuberoinfundibular DA neurons.     

Changes in innate forms of motor behavior in rats during long-term hypokinesia

The structure of motor behaviour in response to environmental tests--"open field" and "with-a-partner" situation (according to P. V. Simonov)--was studied in rats after 1, 3 and 6 weeks of hypokinesis, (to K. Hecht), as compared to the control. In control animals a relatively low level of orienting-investigation reactions and of grooming was observed as well as a low alimentary activity, which is considered as a manifestation of innate passive defensive reactions in the above situations. Disappearance of these reactions in the course of hypokinesia has two stages: predominant increase in orienting-investigating reactions (1-3 weeks); their subsequent decrease and an increase in the grooming (after 6 weeks). The relation between innate and conditioned behavioural changes is discussed as well as stability of alimentary behaviour in rats.     

Sexual differences in the interhemispheric asymmetry of the transcallosal responses of the associative areas in the cat neocortex

Sex differences of hemisphere asymmetry of homo- and heterotopic transcallosal responses in association cortex of 48 cats (24 male and 24 female) immobilized by tubocurarine have been studied by means of topographic EPs recordings in both hemispheres. In males left hemisphere dominates by the amplitude of homotopic and positive wave of heterotopic EPs and right hemisphere dominates by the amplitude of negative wave of heterotopic sensorimotor cortex EPs. The individual asymmetry of EPs has been observed in sensomotor cortex of females and in parietal cortex of animals of both sex. The interhemispheric asymmetry is expressed distinctly in females than in males. It is concluded that sex dimorphism is present in functional organization of associative system of (callosal and intracortical) connections in cat's neocortex projection and association areas which means its more expressed hemisphere lateralization in males with more expressed interhemispheric asymmetry of functional transcallosal connections in females.     

The role of individual characteristics and learning in the manifestation of motor asymmetry in rats

Relative role was studied of the "initial" preference (caused by animals individual properties) and learning in real preference of one limb in rats. After a short-time learning to get food from a narrow horizontal pipe only by the left paw a retrograde amnesia was evoked in rats. At preference determination after three weeks, in conditions which allowed to get food by any paw, in the group of animals without amnesia the number of the left-handed rats was 5.7 times more than of the right-handed ones. In the group of animals with amnesia the numbers of the left-handed, right-handed and ambidextrous were approximately equal. Correlation was revealed between the speed of learning to get food by the left paw and the number of attempts to use the right paw. It has been shown that the initial preference may be stably changed even by a short-time learning (3 food seizures). By the degree of manifestation of the initial preference the rats form a continuum with a gradual transition from pronounced right-handed animals to pronounced left-handed ones. The weaker is the initial preference, the greater the role of learning in the real preference of one of the paws.     

Interhemispheric motor asymmetry of conditioned feedback

The interhemispheric asymmetry and lateralization of motor functions, as applied to backward conditioning, was studied in two dogs that afterwards turned to be a right-hander and a left-hander. In the process of food-procuring instrumental conditioning it was revealed that one of the dogs predominantly used the right paw (with the dominance of the left hemisphere) and the second animal used the left paw (the right brain hemisphere dominated). The earliest signs of lateralization of the motor functions were observed in the backward conditioned connections (which had been formed earlier than the direct connections or direct conditioned reflexes). Consequently, the presence and sign of asymmetry can be predicted on the basis of manifestation of the backward connections observed at the early stages of acquisition of food-procuring behavior. The backward connections are strictly specific and have the same lateralization as the direct ones.     

Lack of limb motor asymmetry in the neonate

Neonates were examined for evidence of lateralization of motor function. The stepping test was done and the foot that moved first was recorded. The reaction of both arms to avoid an obstacle was also tested. No evidence for lateralization was found. Previous studies in the neonate have shown asymmetry of anatomical structures subserving language, and functional asymmetry of auditory functions and head position. However, the development of limb handedness occurs only at a later age.     

Sexual forms of yeasts in clinical samples

The sexual or teleomorphic state of yeasts has only been described in a few clinically involved species, mainly those of the Saccharomycetaceae family. With the aim of gathering information on their incidence in human pathology, a study has been made of a total of 2,135 strains isolated from clinical samples and cultivated in McClary agar. From these, 8 strains in teleomorphic state were identified: Kluyveromyces marxianus [1], Pichia anomala [2], Pichia farinosa [1], Pichia membranaefaciens [1] and Saccharomyces cerevisiae [3]. The two strains of P. anomala were responsible for fungemia; K. marxianus and the two strains of S. cerevisiae produced vaginitis; the other strains were oral cavity colonizers.     

Relationship between certain forms of catalepsy in rats. An attempt at genetic analysis]

Rats from strain GC selected for predisposition to "pseudocatalepsy" (a cataleptic response to an enforced vertical posture) are also characterized by an increased duration of pinch-induced catalepsy. Expression of catalepsy in F1 and segregation in F2 hybrids obtained from GC x Wistar crossing were analyzed. The results obtained indicate that a monogenic dominant inheritance with incomplete penetrance cannot be ruled out for both pseudocatalepsy and pinch-induced catalepsy.     

Thyroliberin-induced motor asymmetry as an indicator of the individual behavioral strategy of rats in a radial labyrinth

The individual peculiarities of functional changes in motor asymmetry determined by behavioral test in T-maze have been shown in experiments with rats (nonpedigree and line LATI). The application of thyroliberin (10 mkg/kg) causes and increases the left-side lateralization which introduces alteration in the individual strategy of the successive round of 12 rays of radial maze with food during solution of spatial orientation task.