A dynamical measure of the black hole mass in a quasar 11 billion years ago

Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)1-3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase4-6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3)7. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-μas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 108 solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 1011 solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems.

Radio-Tracking Study of Foxes’ Movements Related to their Home Range. A Cognitive Map Hypothesis

A radio-tracking study of foxes’ movements ( Vulpes vulpes L.) was conducted in the Chizé Forest (France). Five foxes captured as adults returned to their trapping zone during the night following their release, and very soon showed a settled occupation of their home-range. Their utilization of the home range changed in time. In the movements of adult foxes, the presence of a network of preferred ways, mainly situated along the forest roads, could be detected. The animals, however, also moved around a great deal without using this preferred network. Two foxes, captured young and sub-adult, showed first a period of erratic movements before they started coming back to the same burrow. The first movements they made from that burrow were very variable. The variability of foxes’ movements is discussed in relation to the notion of a cognitive map.

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with [Formula: see text] eV by analyzing cosmic rays with energies above [Formula: see text] eV arriving within an angular separation of approximately 15[Formula: see text]. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.

G-protein-coupled receptor oligomers: two or more for what? Lessons from mGlu and GABAB receptors

G-protein-coupled receptors (GPCRs) are key players in the precise tuning of intercellullar communication. In the brain, both major neurotransmitters, glutamate and GABA, act on specific GPCRs [the metabotropic glutamate (mGlu) and GABA(B) receptors] to modulate synaptic transmission. These receptors are encoded by the largest gene family, and have been found to associate into both homo- and hetero-oligomers, which increases the complexity of this cell communication system. Here we show that dimerization is required for mGlu and GABA(B) receptors to function, since the activation process requires a relative movement between the subunits to occur. We will also show that, in contrast to the mGlu receptors, which form strict dimers, the GABA(B) receptors assemble into larger complexes, both in transfected cells and in the brain, resulting in a decreased G-protein coupling efficacy. We propose that GABA(B) receptor oligomerization offers a way to increase the possibility of modulating receptor signalling and activity, allowing the same receptor protein to have specific properties in neurons at different locations.

Vasopressin and galanin expression in the hypothalamus of two African rodents, Taterillus gracilis and Steatomys caurinus, subjected to water-restriction

The expression of arginine-vasopressin (AVP) and galanin (GAL) was studied by immunohistochemistry and in situ hybridization in the hypothalamus of two species of African rodents. In the wild, these animals experience successive arid and wet seasons that alternately stimulate their antidiuretic and diuretic systems. In this study, animals were subjected to both standardized laboratory conditions and to eight days of water-restriction. Under both sets of conditions, AVP and GAL were detected in the supraoptic nucleus (SON), paraventricular nucleus (PVN), and median eminence (ME). AVP and GAL responses to water-restriction differed in the two species, as did behavioral adaptations to the hot-dry season. In Taterillus gracilis, AVP- and GAL-LI (like immunoreactivity) peptide and mRNA levels increased in the SON. AVP-LI peptide and mRNA levels increased in the PVN, whereas only AVP-LI peptide levels increased in the ME. Pituitary gland AVP pools were unchanged by water deprivation, whereas urinary AVP levels and osmolality increased. The AVP response is typical of that of desert rodents, favoring survival under conditions of water-restriction. In Steatomys caurinus, which estivates, AVP and GAL-LI peptide levels decreased in the hypothalamus, as they did in the laboratory rat. In the SON, AVP, and GAL mRNA levels increased, whereas, in the PVN, only AVP mRNA levels increased. Pituitary gland AVP levels decreased, whereas urinary AVP levels and osmolality increased. In both species, the changes in the amount of GAL-LI peptide appeared to be closely linked to changes in AVP levels, suggesting that this peptide is involved in the osmoregulatory response to water-restriction.

Effects of pinealectomy on glucagon responsiveness to hypoglycaemia induced by insulin injections in fed rats

The glucagon response to insulin-induced hypoglycaemia was tested in rats that had been pinealectomised (Px), pinealectomised and fitted with melatonin implants (Px + MLT), or sham-operated (SO). The glucagon response to hypoglycaemia observed in SO rats (216 +/- 27 pg x ml(-1) at baseline versus 397 +/- 35 pg x ml(-1) at the hypoglycaemic peak, mean +/- S.D.) was stronger than that in Px rats (180 +/- 37 pg x ml(-1) and 229 +/- 21 pg x ml(-1), respectively) and weaker than that in Px + MLT rats (256 +/- 19 pg x ml(-1) and 516 +/- 11 pg x ml(-1), respectively). Our data indicate that the capacity to release glucagon during insulin-induced hypoglycaemia is altered in pinealectomised rats.

Involvement of the suprachiasmatic nucleus in diurnal ACTH and corticosterone responsiveness to stress

We explored the contribution of the suprachiasmatic nucleus (SCN) in ACTH and corticosterone (CORT) diurnal responsiveness of the rat to restraint stress applied either in the morning (AM) or in the evening (PM). Ablation of the SCN caused the diurnal rhythmicity of the CORT response to disappear but had no effects on AM vs. PM differences in the ACTH response. Stress-response curves in SCN-lesioned rats that had prestress levels of CORT either in the AM range or in the PM range, when compared with those obtained for AM and PM controls, showed that the SCN differentially regulates the stress response depending on the underlying secretory activity of the adrenal cortex. When basal CORT secretion is at its lowest, the SCN inhibits CORT responsiveness to stress by controlling pituitary corticotrophs; but when it is at its highest, it has a permissive action that will bypass the hypophysis and reach the adrenals to adjust the response of the gland to ACTH.

Effects of bilateral ganglionectomy and melatonin replacement on seasonal rhythm of testicular activity in Zembra Island wild rabbits (Oryctolagus cuniculus)

This study examined the effects of subcutaneous melatonin implants on testicular activity (testis volume and plasma testosterone) in wild rabbits (Oryctolagus cuniculus) captured on Zembra Island (North Tunisia) and maintained in natural temperature and photoperiod conditions. The period of testicular activity was 2 months longer in intact animals with melatonin implants than in intact animals without melatonin implants. After bilateral superior cervical ganglionectomy, testicular activity was inhibited and no spontaneous recrudescence in gonadal function was observed during the 13 months of the experiment, demonstrating the absence of an endogenous circannual rhythm of reproductive function in this species. Renewed testicular activity was observed 2 months after the insertion of melatonin implants in ganglionectomized animals. These results confirm that testicular activity is stimulated by short days in late autumn and that melatonin reactivates the reproductive axis in this species. This finding is in contrast to that in continental populations of wild rabbits in which reproduction is inhibited by short days or melatonin. These results are discussed in terms of insularity and may reflect the geographical isolation of this population.

Cardiac natriuretic peptide response to water restriction in the hormonal adaptation of two semidesert rodents from West Africa (Steatomys caurinus, Taterillus gracilis)

Two African rodents, Taterillus gracilis and Steatomys caurinus, native to regions of alternate dry and wet seasons, were studied under laboratory conditions. These species differ in estivation behavior, one undergoing pseudoestivation and the other strong estivation. One group of animals of each species was provided with unlimited access to seed and vegetables rich in water, mimicking the food availability of the wet season (control group). A second group of animals of each species was subjected to water restriction for 8 days, mimicking the natural drought that occurs during the dry-hot season. The effects of water restriction on osmoregulation and body water content were assessed from hematocrit, and plasma and urinary osmolalities (PO, UO). Whether the natriuretic peptide system was modified by the osmoregulator adaptation to aridity of these semidesert rodents was examined from measurements of atrial natriuretic peptide (ANP) levels in plasma, atria, and ventricles, in parallel with morphological studies. In both species, UO was increased by water restriction. In water-deprived T. gracilis, ANP levels were about twice (right atria: 1.08 +/- 0.16 microg/mg protein vs control: 0.40 +/- 0.06 microg/mg protein) and plasma concentrations half (0.28 +/- 0.06 ng/ml vs control: 0.64 +/- 0.07 ng/ml) those in control animals. In S. caurinus these variables were not affected by water availability (right atria water restricted: 2. 20 +/- 0.15 microg/mg protein vs control: 2.86 +/- 0.37 microg/mg protein; plasma ANP water restricted: 0.80 +/- 0.12 ng/ml vs control: 0.90 +/- 0.16 ng/ml). Consistent with these quantitative results, immunohistochemical and ultrastructural observations showed an increase in immunostaining for both the N- and the C-terminal ANP and a larger number of granules in the atria of T. gracilis following water restriction, whereas there was no visible change in S. caurinus. Thus, water restriction induced a decrease in ANP secretion in T. gracilis, increasing cardiac storage alongside a reduced urine production. In contrast, in S. caurinus, the natriuretic system was not affected by an 8-day period of water restriction.

Glucocorticoids up-regulate the expression of glial fibrillary acidic protein in the rat suprachiasmatic nucleus

Immunoreactivity against glial fibrillary acidic protein (GFAP) was used as a dynamic index in adrenalectomized rats subjected or not to corticosterone replacement to investigate whether glucocorticoids may interact with astrocytes in the suprachiasmatic nucleus (SCN), the master component of the central circadian clock. GFAP staining in the SCN was significantly higher in rats having received implants that restored physiological plasma levels of corticosterone within diurnal or nocturnal limits than in non-normalized rats. The effects of corticosterone were similar in the parvocellular portion of the paraventricular nucleus but were opposite in the hippocampus, another major site of negative feed-back regulation of the hypothalamic-pituitary-adrenal axis, where a decreased GFAP staining was observed in discrete regions of the dentate gyrus. This indicates that glucocorticoids may positively or negatively regulate GFAP, depending on the target brain structure. In the SCN, that contains only few if any glucocorticoid receptors, indirect mechanisms that may involve serotoninergic neurons are probably responsible for the effects of corticosterone level. It is proposed that the corticosterone-induced increase in GFAP staining in that nucleus accounts for dynamic changes in neurone-astrocyte interactions that might occur in relation with natural fluctuations of glucocorticoids over the 24 h period.

Hindlimb-suspension and spaceflight both alter cGMP levels in rat choroid plexus

Effects of actual and simulated weightlessness on choroidal guanylate cyclase activity were evaluated by assaying the production of cyclic guanosine monophosphate (cGMP), a second messenger involved in mechanisms regulating the secretion of cerebrospinal fluid (CSF) in choroid plexus. Cyclic cGMP was measured, using radio-immunoassay, in choroidal extracts of hindlimb-suspended rats (HLS rats), adapted to an anti-orthostatic restraint for 30 min., or for 3, 9 or 14 days and after a 17-day spaceflight (Life and Microgravity SpaceLab experiment; LMS). Basal cGMP levels were slightly but significantly decreased in the first 30 min. of the HLS experiment, whereas they were significantly increased in rats adapted to longer anti-orthostatic restraints. LMS flight rats demonstrated a similar increase in the choroidal cGMP baseline. After natriuretic peptide stimulation, i.e. using ANP (atrial natriuretic peptide) or BNP (brain natriuretic peptide), choroidal cGMP contents were typically increased (by 1.5-2 times; p<0.05) in control rats (LMS and HLS experiments), but not significantly elevated in suspended rats, except for those adapted to HLS for 14 days. In these animals the ANP-dependent cGMP production was significantly increased (by about 3 times; p<0.005). The ANP- or BNP-dependent responses were similarly abolished in LMS flight rats, which were dissected 4-6 hours after return to Earth's gravity. The role of corticosteroids was also investigated during the LMS experiment. Results on choroidal functions revealed a lack of significant change of cGMP levels between adrenalectomized and sham-operated rats. For the first time, it is reported that both basal and ANP- stimulated cGMP levels are dramatically changed over the first 14 days of suspension, i.e. with experiments known to simulate some effects of weightlessness. Basal choroidal cGMP levels are also increased after 17 days in space, suggesting that space adaptation also impacts choroidal guanylate cyclase activities. However, the absence of ANP-dependent cGMP increase, observed in LMS flight animals, suggests that HLS could not simulate all the spaceflight effects. Thus, these preliminary results seem to show that a natriuretic peptides-independent s stem is involved in choroidal adaptation to spaceflight.

[Antimicrobial resistance among species of Salmonella, Shigella, Escherichia, and aeromonas isolated from children with diarrhea in 7 Argentinian centers]

The increasing levels of resistance of enteropathogenic bacteria against antimicrobial agents present geographic variations. We have analysed the antimicrobial susceptibility of isolates obtained from 4,364 children under 5 years of age with acute diarrhea, in 7 cities of Argentina. Diarrheagenic E. coli exhibited 74.5% of resistance against ampicillin, 64.2% against sulfametoxazole-trimethoprim, and Shigella spp., 62% and 75.6% respectively. Salmonella sp. showed 35%, 14%, 41.8%, 65.4%, 14.5%, and 13.6% of resistance against ampicillin, chloranfenicol, sulfametoxazole-trimetoprim, sulfadiazin, gentamycin, and fosfomycin respectively. These values are higher than the ones observed in developed countries. Aeromonas showed significantly lower resistance percentage. Important differences in our country were observed, consequently, local trials should be carried out in order to apply corrective measures.

Minor head injury at paediatric age in Argentina

BACKGROUND

To evaluate epidemiologic factors in relation to paediatric head injury in the city of Mar del Plata, Argentina.

METHODS

Retrospective (12-month) and prospective (6-month) evaluations were carried out on a total of 2,492 children with head injury (age range 0-15 years), taking into account sex, age, cause of injury, time of injury, incidence of hospitalisation, and the occurrence of fractures on conventional X-ray and computarized tomography (CT) scans of the head. Data were compiled and analyzed through a register called "Traumatic Brain Injury Register".

RESULTS

From the total 2,492 children entered in the registry, 62% were males and 38% females. Age distribution was as follows: 33.5% from 0-2 years, 43.8% from 3-9 years, and 22.7% from 10-15 years. Falls were the main cause of head injury in children under 3 years of age, whereas car accidents prevailed among older groups (chi2 = 216.00, p<0.0001). Injuries occurred most frequently (84.7% of the cases) between 12:00 hrs and 24:00 hrs. From the total sample, 1,015 children (19.9%) required hospitalisation. Skull fractures were identified on conventional X-rays in 14.9% of the cases, and there was a direct relationship between skull X-rays and CT scans with respect to skull fractures (chi2 = 13.13, p<0.0001). The overall incidence of paediatric head injuries was 566 cases per 100,000 population and mortality rate was 4.65 per 1,000 head injuries.

CONCLUSIONS

Our figures revealed an overall incidence of paediatric head injuries, which is 2.97 higher than the international average, suggesting that accident prevention measures should be further implemented.

Ependymal and choroidal cells in culture: characterization and functional differentiation

During the past 10 years, our teams developed long-term primary cultures of ependymal cells derived from ventricular walls of telencephalon and hypothalamus or choroidal cells (modified ependymal cells) derived from plexuses dissected out of fetal or newborn mouse or rat brains. Cultures were established in serum-supplemented or chemically defined media after seeding on serum-, fibronectin-, or collagen-laminin-coated plastic dishes or semipermeable inserts. To identify and characterize cell types growing in our cultures, we used morphological features provided by phase contrast, scanning, and transmission electron microscopy. We used antibodies against intermediate filament proteins (vimentin, glial fibrillary acidic protein, cytokeratin, desmin, neurofilament proteins), actin, myosin, ciliary rootlets, laminin, and fibronectin in single or double immunostaining, and monoclonal antibodies against epitopes of ependymal or endothelial cells, to recognize ventricular wall cell types with immunological criteria. Ciliated or nonciliated ependymal cells in telencephalic cultures, tanycytes and ciliated and nonciliated ependymal cells in hypothalamic cultures always exceeded 75% of the cultured cells under the conditions used. These cells were characterized by their cell shape and epithelial organization, by their apical differentiations observed by scanning and transmission electron microscopy, and by specific markers (e.g., glial fibrillary acidic protein, ciliary rootlet proteins, DARPP 32) detected by immunofluorescence. All these cultured ependymal cell types remarkably resembled in vivo ependymocytes in terms of molecular markers and ultrastructural features. Choroidal cells were also maintained for several weeks in culture, and abundantly expressed markers were detected in both choroidal tissue and culture (Na+-K+-dependent ATPase, DARPP 32, G proteins, ANP receptors). In this review, the culture models we developed (defined in terms of biological material, media, substrates, duration, and subculturing) are also compared with those developed by other investigators during the last 10 years. Focusing on morphological and functional approaches, we have shown that these culture models were suitable to investigate and provide new insights on (1) the gap junctional communication of ependymal, choroidal, and astroglial cells in long-term primary cultures by freeze-fracture or dye transfer of Lucifer Yellow CH after intracellular microinjection; (2) some ionic channels; (3) the hormone receptors to tri-iodothyronine or atrial natriuretic peptides; (4) the regulatory effect of tri-iodothyronine on glutamine synthetase expression; (5) the endocytosis and transcytosis of proteins; and (6) the morphogenetic effects of galactosyl-ceramide. We also discuss new insights provided by recent results reported on in vitro ependymal and choroidal expressions of neuropeptide-processing enzymes and neurosecretory proteins or choroidal expression of transferrin regulated through serotoninergic activation.

Choroidal readaptation to gravity in rats after spaceflight and head-down tilt

To determine when choroidal structures were restored after readaptation to Earth gravity or orthostatic position, fine structure and protein distribution were studied in rat choroid plexus dissected either 6 h [Space Life Sciences-2 (SLS-2) experiments] or 2 days [National Institutes of Health-Rodent 1 (NIH-R1) experiments] after a spaceflight, or 6 h after head-down tilt (HDT) experiments. Apical alterations were noted in choroidal cells from SLS-2 and HDT animals, confirming that weightlessness impaired choroidal structures and functions. However, the presence of small apical microvilli and kinocilia and the absence of vesicle accumulations showed that the apical organization began to be restored rapidly after landing. Very enlarged apical microvilli appeared after 2 days on Earth, suggesting increased choroidal activity. However, as distributions of ezrin and carbonic anhydrase II remained altered in both flight and suspended animals after readaptation to Earth gravity, it was concluded that choroidal structures and functions were not completely restored, even after 2 days in Earth's gravity.

Effects of bilateral olfactory bulbectomy on circadian rhythms of ACTH, corticosterone, motor activity and body temperature in male rats

Bilateral olfactory bulbectomy (BOX) has major biochemical and behavioral effects, and is one of the most widely investigated of animal models of depression. We studied the consequences of BOX in male rats, on the organization of endogenous circadian rhythms for ACTH, corticosterone (Cort), motor activity (MA) and body temperature (BT). Mean levels were increased for Cort and MA, whereas no significant changes were observed for ACTH and BT. Significantly higher plasma Cort morning values were evidenced in BOX than sham-operated animals. In addition, compared with the single prominent power spectrum for the 24 hours period of control rats, the BOX animals displayed substantially lower 24 hours spectral power for the MA and BT circadian rhythms. These alterations suggest that olfactory bulbectomy, by disruption of the afferences and efferences, induced drastic changes in the function of the endogenous clock or of its regulating systems. From this point of view, bulbectomized rats may therefore be a valuable model to studying the etiology of psychiatric disorders with rhythm disturbance.

Effects of an 11-day spaceflight on the choroid plexus of developing rats

Cellular distributions of ezrin, a cytoskeletal protein involved in apical cell differentiation in choroid plexus, and carbonic anhydrase II, which is partly involved in the cerebrospinal fluid production, were studied by immunocytochemistry, at the level of choroidal epithelial cells from the lateral, third and fourth ventricles in normal or experimental fetuses, in parallel with the ultrastructure of apical microvilli, observed by transmission electron microscopy. We compared choroid plexuses from developing normal rats (gestational day 15 to birth) with choroid plexuses from 20-day-old rat fetuses, developed for 11 days in space, aboard a space shuttle (NASA STS-66 mission, NIH-R1 experiments), from gestational day 9 to day 20. The main changes observed in fetuses developed in space were demonstrated by immunocytochemistry and concerned the distribution of ezrin and carbonic anhydrase II. Thus, in fetuses developing in space, ezrin was strongly detected in the choroidal cytoplasm and weakly associated to the membrane in the apical domain of the choroid plexus from the fourth ventricle. Such alterations suggested that choroid plexus from rat fetal brain displays a delayed maturation under a micro-gravitational environment. In contrast, intense immunoreactions to anti-carbonic anhydrase II antibodies showed that this enzyme is very abundant in rats developed in space, compared to ground control fetuses.

Effects of acute tilt from orthostatic to head-down antiorthostatic restraint and of sustained restraint on the intra-cerebroventricular pressure in rats

The tail-cast suspension rat model was developed to explore in ground laboratories the physiological effects of some of the stresses prevailing during space flight including and among them those of the headwards body fluid shifts. We recently showed in rats that an acute head-down tilt (45 degrees) from tail-cast orthostatic (OR) to antiorthostatic restraint (AOR) induced within 30 min and for 2 to 4 h an acute stress-like surge in plasma ACTH and corticosterone levels. Considering the proximity of the CRF producing neurons with the 3rd ventricle, we decided to explore the acute and longer-term effects of the OR/AOR tilt on the intra-cerebroventricular pressure (Picv) measured with an indwelling sensor-transmitter catheter stereotaxically implanted in the 3rd ventricle. At 1- or 10-min intervals the unit sent radiotelemetric signals for both Picv and motor activity (MA) to a receiver coupled with an automatic data analyser. The acute AOR-tilt induced within 10 min and for 60 min a 2.5-fold rise in Picv which receded to baseline between 60 and 90 min. During this time, the normally close correlation between Picv and MA was lost, as assessed by Spearman's rank coefficient. In a long-term experimental series we explored the evolution of both Picv and MA in individual rats subjected successively to a 7 day control phase (C). 7 days OR, and 3 days AOR. After the 1-h-long post-tilt rise of the Picv, the mean Picv levels measured for the next 3 days decreased significantly vs. both the preceding OR phase (-30%) and the initial C Phase (-40%). The circadian pattern of the diurnal Picv profile was impaired, as evidenced by a significant fall (i) in the night/day ratio (-25% vs. C). and (ii) even more in the spectral power of the circadian 1 c/24 h frequency (-85% vs. C). The simultaneously recorded MA fluctuations similarly displayed an altered diurnal pattern with a spectral power of the circadian frequency reduced to 7% of controls. However, contrary to the short-term experiment, in the long-term study the large alterations to both Picv and MA were strongly correlated, as during the control phase. The mechanisms involved in the swift post-tilt rise in the Picv together with an aroused corticotropic axis, and in the impact of sustained head-down restraint on CNS-controlled adaptive regulations including their circadian rhythms remain unknown.

Changes in apical organization of choroidal cells in rats adapted to spaceflight or head-down tilt

Structural changes observed in choroid plexuses from rats dissected aboard a space shuttle, on day 13 of an orbital flight (NASA STS-58 mission, SLS-2 Experiments) demonstrated that choroidal epithelial cells display a modified organization in a microgravitational environment. Results were compared with ultrastructural observations of choroid plexus from rats maintained under anti-orthostatic restraint (head-down tilt) for 14 days. In both experiment types, the main alterations observed by transmission electron microscopy, at the level of choroidal epithelial cells from the third and fourth ventricles, concerned the formation and the organization of apical microvilli, whereas pseudopod-like structures appeared. Immunocytochemical distribution of ezrin, a cytoskeletal protein involved in apical cell differentiation in choroid plexus, confirmed the structural alteration of microvilli in head-down tilted rats, Kinocilia tended to disappear from the apical surface, suggesting a partial loss of cell polarization. In addition, large amounts of clear vesicles were gathered in the apical cytoplasm of choroidal epithelial cells. Disorganization of apical microvilli accumulations of apical vesicles and partial loss of cell polarity showed that long-stays in weightlessness induced alterations in the fine structure of choroid plexus, consistent with a marked reduction of cerebrospinal fluid production.

Different responses of plasma ACTH and corticosterone and of plasma interleukin-1 beta to single and recurrent endotoxin challenges

In a parallel study in 10 individual rats, three time series of plasma concentrations of ACTH, corticosterone (CORT), and interleukin-1 beta (IL-1 beta) were measured before (time 0) and at intervals between 15 and 480 min following intra-arterial (i.a.) infusions of 25 microgram/kg lipopolysaccharide (LPS). All LPS injections were given at 9 AM. The first time series was performed on naive rats (day 1). A sequence of six daily injections (days 3-8) of the same dose of LPS followed. The post-LPS time course of the plasma ACTH, CORT and IL-1 beta levels were studies on days 3 (second injection) and 8 (seventh injection). The first LPS injection induced a rapid (30 min) eightfold rise in plasma ACTH and CORT, culminating in concentrations 30 times the baseline at 60 min (ACTH) and 15 times baseline at 120 min (CORT). Both hormones receded back to the initial basal level at 480 min. On the other hand, IL-1 beta increased slowly to peak at 13 times baseline 120 min before declining to minimal seven- to ninefold basal levels, 480 min and even 48 h post-LPS. During the second phase of the experiment starting 48 h after the initial LPS priming sequence, the ACTH and CORT responses to daily recurrent LPS injections again differed from those of IL-1 beta. The post-LPS time courses of the ACTH and CORT reaction displayed a typical pattern of a progressive attenuation studied at days 3 and 8. The peak amplitudes at days 3 and 8 were reduced to 60 and 10%, respectively, for ACTH, and to 85 and 45% for CORT of those observed at the first LPS test. The duration of the response (both) was also shortened from 480 min (first LPS test) to 300 min at days 3 and 8. The post-LPS patterns of the IL-1 beta responses were characterized, first by basal levels seven to nine times higher than the initial baseline values (day 1), and by a rapid suppression of the post-LPS response, with only a slight (30%) increase at day 3 and no increase at day 8. Thus, after both acute and recurrent LPS administration, ACTH/CORT and IL-1 beta reacted differently to the endotoxin challenge. The two LPS reactive systems were not correlated. This is inconsistent with the often proposed role of increased plasma IL-1 beta release as an intermediary factor in the LPS-induced recruitment of the corticotropic axis in general infections.

Choroidal responses in microgravity. (SLS-1, SLS-2 and hindlimb-suspension experiments)

Fluid and electrolyte shifts occurring during human spaceflight have been reported and investigated at the level of blood, cardiovascular and renal responses. Very few data were available concerning the cerebral fluid and electrolyte adaptation to microgravity, even in animal models. It is the reason why we developed several studies focused on the effects of spaceflight (SLS-1 and SLS-2 programs, carried on NASA STS 40 and 56 missions, which were 9- and 14-day flights, respectively), on structural and functional features of choroid plexuses, organs which secrete 70-90% of cerebrospinal fluid (CSF) and which are involved in brain homeostasis. Rats flown aboard space shuttles were sacrificed either in space (SLS-2 experiment, on flight day 13) or 4-8 hours after landing (SLS-1 and SLS-2 experiments). Quantitative autoradiography performed by microdensitometry and image analysis, showed that lateral and third ventricle choroid plexuses from rats flown for SLS-1 experiment demonstrated an increased number (about x 2) of binding sites to natriuretic peptides (which are known to be involved in mechanisms regulating CSF production). Using electron microscopy and immunocytochemistry, we studied the cellular response of choroid plexuses, which produce cerebrospinal fluid (CSF) in brain lateral, third and fourth ventricles. We demonstrated that spaceflight (SLS-2 experiment, inflight samples) induces changes in the choroidal cell structure (apical microvilli, kinocilia organization, vesicle accumulation) and protein distribution or expression (carbonic anhydrase II, water channels,...). These observations suggested a loss of choroidal cell polarity and a decrease in CSF secretion. Hindlimb-suspended rats displayed similar choroidal changes. All together, these results support the hypothesis of a modified CSF production in rats during long-term (9, 13 or 14 days) adaptations to microgravity.

Chronic orthostatic and antiorthostatic restraint induce neuroendocrine, immune and neurophysiologial disorders in rats

The tail-cast suspension rat model has been developed in ground laboratories interested in space physiology for extensive study of mechanisms causing the pathophysiological syndrome associated with space flights. We used individually-caged male rats to explore the effects of acute and chronic (7d) orthostatic restraint (OR) and head-down anti-orthostatic restraint (AOR) on a series of physiological variables. The acute restraint study showed that (1) the installation of the OR device induced an acute reaction for 2 days, with a substantial rise in ACTH (x2) and CORT (x6), and that (2) the head-down tilt from OR to AOR induced (i) within 10 min and lasting 60 min a 2-fold rise in the intra-cerebro-ventricular pressure (Picv) monitored with an icv telemetric recording system, which receded to normal between 60 and 120 min; and (ii) within 30 min a short-lived 4-fold rise in plasma ACTH and CORT levels. Chronic OR induced (1) the suppression of the diurnal ACTH/CORT rhythm, with increased mean levels, especially for ACTH, (2) a degraded circadian locomotor activity rhythm manifested by a significant reduction in the spectral power of the 24h periodicity and a concomitant emergence of shorter (ultradian) periodicities, (3) an associated, but less pronounced alteration of the diurnal rhythm in body temperature; and (4) a marked increase in baseline plasma levels of IL-1 beta and an increased reactivity in cytokine release following an E. coli endotoxin (LPS) challenge. AOR induced (1) a similar obliteration of the circadian ACTH/CORT rhythm, (2) the loss of close correlation between ACTH and CORT, (3) a generalized increase in baseline plasma IL-1 beta levels and (4) more extensive degradation of the circadian periodicity for both locomotor activity and, to a lesser extent, body temperature, replaced by dominant spectral powers for ultradian periodicities (3 to 10h). In conclusion, both experimental paradigms--but AOR more than OR--caused a blockade of the circadian rhythmicity of major physiological variables, the loss of normal correlations between ACTH and CORT, and inflammatory-immune hyperreactivity. These pathophysiological disorders may all be parts of a complex chronic stress syndrome.

Seasonal variations of pulsatile luteinizing hormone release in the mink (Mustela vison)

The pulsatile secretion of the hypophyseal luteinizing hormone (LH) is induced by the pulsatile secretion of the hypothalamic neurons secreting gonadotrophin-releasing hormone (GnRH). Seasonal variations in the pulsatility of LH were studied in the adult male mink (Mustela vison), reared under natural environmental conditions. Twenty-one animals were studied according to five critical phases in the breeding season: (1) the terminal phase of sexual quiescence, which precedes renewal of gonadal activity (October-November); (2) renewal of gonadal activity (December); (3) maximum gonadal activity at the height of the breeding season (February); (4) reduction of testicular activity (April); and (5) the initial phase of testicular quiescence (June). Levels of gonadal growth and activity were used to define each phase. A second animal group was studied after being reared for 2 months in an experimental gonado-inhibitory photoperiod, which, necessarily for the mink, was of the "long-day" type: 20L:4D regimen in the present study. Results, obtained with fully conscious animals, provide evidence for the pulsatile secretion of gonadotrophic hormone in this species. In spite of inter-individual differences in pulse patterns, particularly in phases 1 and 2, the pulsatile character of LH secretion is seen to vary markedly as a function of gonadal activity. The variations reflect an increase of hypophyseal activity as early as the preparative phase to the breeding season, and a decrease of activity during the testicular regression phase, which is followed by the onset of gonadotrophic quiescence in June. The main parameter affected statistically by these seasonal fluctuations is pulse frequency; variations in pulse frequency correlated with variations in mean plasma concentrations of LH. In the experimental gonado-inhibitory photoperiod, which led to a severe reduction in gonadal activity, all hormonal pulsatility parameters were statistically reduced; this confirms the importance of photoperiodic control of reproduction in Mustela vison. Several possible mechanisms are proposed for photoperiodic control.

Chronic restraint enhances interleukin-1-beta release in the basal state and after an endotoxin challenge, independently of adrenocorticotropin and corticosterone release

To explore the interactions between the hypothalamic-pituitary-adrenocortical axis and the immune system under stress conditions, we used an experimental rat model for chronic tail-restraint devised earlier for ground studies in space physiology. The system was used in two positions: (1) the orthostatic restraint position (OR) and (2) the antiorthostatic position (AOR) after the rat hind limbs had been raised by a head-down tilt. After 7 days of either restraint, sequential blood samples were taken via an indwelling aortic cannula, before and at various time intervals between 15 and 300 min after an intravascular infusion of 25 micrograms/kg lipopolysaccharide (LPS). The plasma titers of adrenocorticotropin (ACTH), corticosterone (CORT) and interleukin-1 beta (IL-1 beta) were assayed. Under basal conditions, both OR and AOR restraints induced a 5-fold increase in IL-1 beta with no significant changes in ACTH and CORT levels. A robust increase in all three variables was observed after LPS injection. However, the IL-1 beta response to LPS was significantly higher in both restrained groups than in controls. Both the amplitude and the percentage of individually restrained rats displaying elevated IL-1 beta levels were increased up to 5 h. In contrast, the ACTH and CORT post-LPS responses were normal in the OR group. They were unusually dissociated in the AOR rats, which displayed depressed ACTH levels associated with slightly increased CORT levels. Our results suggest that immune-neuroendocrine responses to chronic restraint stress may differ from those generally observed in acute stress.

Superior cervical ganglionectomy suppresses circadian corticotropic rhythms in male rats in the short term (5 days) and long term (10 days)

Superior cervical ganglionectomy (SCGx) has drastic effects on numerous hormonal circadian rhythms and particularly on pineal melatonin secretion. We investigated the hormonal consequences of ablation of the superior cervical ganglion on the corticotropic circadian rhythms in the male rat. Plasma were obtained by sampling blood every 4 h, using a chronic carotid cannula. Adreno-corticotropin hormone (ACTH) was assayed by radioimmunoassay (RIA) and corticosterone (B) by radiocompetition. Urinary 6-sulphatoxymelatonin (aMT6s), considered as an index of the pineal gland activity, was assayed by specific RIA: a decrease in the aMT6s concentration after ganglionectomy was taken as proof of adequate surgical operation. Control animals showed classical circadian rhythms for ACTH and B with basal values during the light phase and circadian peaks around the light/dark interface. Five and ten days after ganglionectomy, the circadian rhythms of ACTH and B were suppressed. In addition, the mean ACTH concentrations increased significantly 10 days after ganglionectomy compared to those in sham-operated rats and 5 days post-operation group. The mean plasma corticosterone levels were similar in those three groups of animals. This is the first study demonstrating the suppressive effect of superior cervical ganglionectomy on the circadian corticotropic hormonal cycle.

Temperature and water conditions mediate the effects of day length on the breeding cycle of a Sahelian rodent, Arvicanthis niloticus

Laboratory studies of variations in testicular activity (testicular weight and plasma testosterone concentration) were carried out on two populations of Arvicanthis niloticus, a Sahelian rodent that displays the particularity of being able to breed in the dry season. The animals were captured during phases of sexual activity or inactivity and were maintained in the laboratory for 50 days under humid conditions (water-rich diet, 90% atmospheric relative humidity) or dry conditions (water-deficit diet, 20% atmosphere relative humidity) and at low temperatures (20-25 degrees C) or high temperatures (30-35 degrees C). The results show that humid conditions or low temperatures stimulate testicular activity in Arvicanthis niloticus whereas dry conditions or high temperatures inhibit breeding. 1) Humid conditions coupled with low temperatures caused the most marked stimulation of testicular activity and maintained sexual activity at its highest level. 2) Humid conditions coupled with high temperatures, or dry conditions coupled with low temperatures, brought about mild sexual activity in animals that were sexually inactive and a regression of testicular weight and plasma testosterone in animals that were sexually active at the beginning of the experiment. In the latter, the results show that testicular activity was maintained and animals remained capable of breeding. 3) High temperatures and dry conditions inhibited short-day gonadal stimulation. On the other hand, in animals maintained under humid conditions or at low temperatures, gonadal stimulation occurred only under a short photoperiod.(ABSTRACT TRUNCATED AT 250 WORDS)

Diurnal variations of urinary 6-sulphatoxymelatonin in male intact or ganglionectomized mink

The existence of the major urinary metabolite of melatonin, 6-sulphatoxymelatonin (aMT6s), was validated for mink and the 24 hr urinary excretion pattern was determined in intact and superior cervical ganglionectomized animals under different photoperiodic conditions. Within- and between-assay variations, parallelism between serially mid-night pooled urine dilutions and standard curves in aMT6s free urine of mink at 1:125 dilution and recovery of aMT6s in mid-day pooled urine at 1:125 dilution provided a good validation for the mink urinary a MT6s assay. In natural photoperiods (January, LD 9:15; April, LD 13:11) the diurnal rhythm was characterized by low aMT6s values during the day and high values at night. There were no differences in the nocturnal values measured under long- (April, 4.11 +/- 0.40 ng/hr) or short-day (January, 4.74 +/- 0.36 ng/hr) conditions. In an experimental long photoperiod (LD 15:9), the same result was obtained on the 24 hr rhythm in intact animals, but in ganglionectomized mink the nocturnal rise in aMT6s was abolished and the nocturnal values were always low (0.88 +/- 0.09 ng/hr). Our results agree with those obtained in other species concerning plasma melatonin rhythm and urinary aMT6s excretion; we thus conclude that this is an effective assay for measuring pineal activity in mink.

Circadian rhythm of photosensitivity and the adaptation of reproductive function to the environment in two populations of Arvicanthis niloticus from Mali and Burkina Faso

Previous studies have shown that there is a circadian rhythm of photosensitivity in different rodent species of the Sahel (Burkina Faso) and that, despite the low amplitude of seasonal variations in daylength, the photoperiod may control reproductive function. The present investigation of Arvicanthis niloticus provides additional support for this hypothesis. Populations of Arvicanthis niloticus from two regions at the same latitude 1000 km apart but with different climates were studied. Oursi, Burkina Faso, has an arid climate (annual rainfall 315 mm) and Kamalé, Mali has a wetter climate (annual rainfall 1114 mm). The circadian rhythm of photosensitivity had the same features in both populations, involving inhibition of testicular activity, but the photosensitive phase began 11 h 30 min after dawn in the population from Burkina Faso and 45 min later in that from Mali. Comparison of these results with the annual variation of daylength showed that the photoperiod inhibits the reproductive activity of A. niloticus from April to December in Burkina Faso and only from mid-May to mid-August in Mali. The population of Arvicanthis niloticus living in an environment with a large and seasonally stable food supply (Mali) thus has a longer reproductive period. This corroborates results from field studies on annual variations of population density.

Short-day stimulation of testicular activity and immunoreactivity of the hypothalamic GnRH system in mink following deafferentation of the pineal body by bilateral superior cervical ganglionectomy and melatonin replacement

The effects of superior cervical ganglionectomy on testicular function (testis volume and plasma testosterone levels) and the immunocytochemical activity of the GnRH hypothalamic system were studied in the mink, a short-day breeder. Animals reared in a natural photoperiod were (i) ganglionectomized at four different times during the period extending from the end of summer to the end of autumn (September 15, October 20, October 28, and December 1), and (ii) reared for 50 days in a short gonadostimulatory photoperiod (4L:20D). Lastly, an attempt was made to overcome the effects of superior cervical ganglion removal by administering melatonin to mink reared in a natural photoperiod. In mink reared in a natural photoperiod, deafferentation of the pineal on September 15 (L = 12.5 h) or October 20 (L = 10.5 h) resulted in consistently low values of testicular volume and plasma testosterone until the end of the experiment (February). When the operation was performed on October 28 (L = 10 h) testicular activity was initiated but only lasted a short time and did not allow maximal gonadal development. When superior cervical ganglionectomy was carried out on December 1 (L = 8.5 h), during the phase of renewed testicular activity, the increases in testicular volume and testosterone levels were not affected by the operation and the subsequent variation of these parameters was identical to that observed in intact animals. Similarly, in mink reared for 50 days in a photoperiod of 4L:20D before superior cervical ganglionectomy, deafferentation of the pineal did not prevent gonadostimulation induced by short days.(ABSTRACT TRUNCATED AT 250 WORDS)

Suprachiasmatic nucleus lesions abolish photoperiod-induced changes in the testis function and GnRH immunoreactivity in the mink, a short-day breeder

Testicular activity (testis volume and plasma testosterone) and immunoreactive GnRH hypothalamic system were examined after suprachiasmatic nucleus (SCN) lesion in the mink, a short-day breeding mammal, whose sexual activity is inhibited by day lengths exceeding 10 h. In animals maintained under a natural photoperiod, SCN destruction performed during the period of maximum sexual activity (February) was shown to have no effect on onset of the testicular inactive period which begins at the end of winter and continues through spring. On the other hand, while gonadal activity began again at the end of autumn in intact animals, minks that had undergone SCN destruction remained sexually inactive until the end of the experiment period (February). The SCN could thus be crucial to the onset of sexual activity triggered by the reduction of day length, whereas onset of sexual inactivity is a spontaneous phenomenon. This was confirmed in a second experiment demonstrating that a short photoperiod (4 L:20 D), highly gonadostimulatory in intact animals, had no effect on testicular activity after SCN destruction. An immunocytochemical study of the hypothalamic GnRH system (staining intensity and number of labeled perikarya and immunoreactive endings in the external layer of the median eminence) also showed consistent by very low rates of immunoreactivity and number of labeled perikarya and endings in operated animals.

Mollicutes DNA polymerases: characterization of a single enzyme from Mycoplasma mycoides and Ureaplasma urealyticum and of three enzymes from Acholeplasma laidlawii

The DNA polymerase activity of different members of Mollicutes was studied. A single DNA polymerase was found in Mycoplasma mycoides and Ureaplasma urealyticum, type species of the genera Mycoplasma and Ureaplasma, and was compared with the previously described Mycoplasma orale enzyme. Most of their properties were comparable; an immunological relationship was demonstrated between M. orale and M. mycoides enzymes by immunoblotting. In contrast to these results, three different DNA polymerases were purified in Acholeplasma laidlawii, type species of the genus Acholeplasma which, in this aspect, resembles the genus Spiroplasma. A 3'-5' exonuclease activity was found in the different purified preparations. In M. mycoides, M. orale and one of the three A. laidlawii preparations, the 3'-5' exonuclease could be separated from the DNA polymerase by non-denaturing PAGE. The presence of a single DNA polymerase seems to be a typical feature of the Mycoplasmataceae, which include the genera Mycoplasma and Ureaplasma, in contrast to the occurrence of three enzymes within the Acholeplasmataceae and Spiroplasmataceae. These results are in agreement with the phylogenetic tree of Mollicutes proposed from their 5 S and 16 S rRNA sequence comparisons, in which the evolution of Acholeplasma and Spiroplasma branches led, by genome reductions, to Mycoplasma and Ureaplasma species.

Effects of photoperiod, melatonin implants and castration on molting and on plasma thyroxine, testosterone and prolactin levels in the European badger (Meles meles)

1. The seasonal molt, which lasts six months in the badger, begins in mid-July and ends at the beginning of winter. It occurs under natural long-day conditions, following the seasonal drop in plasma testosterone levels, concomitant with high levels of thyroxine and prolactin. 2. To examine the role of the different factors involved (day length, prolactin, thyroxine, testosterone), different groups of badgers, divided into subgroups of castrated or intact animals, were subjected to the influence of long days (20L: 4D), short days (4L:20D) or the effect of subcutaneous melatonin implants. 3. In all cases, castration resulted in a significantly earlier onset of molting 1-3 months, depending on the group, regardless of the experimental conditions (20L:4D, 4L:20D, melatonin). 4. However, molting started earliest in animals subjected to long days, irrespective of whether they were castrated or intact. 5. In the melatonin-implanted badgers, molting started either early (castrated animals), or late or not at all (intact animals). 6. Lastly, in castrated badgers subjected to experimental photoperiods (short days or long days) or melatonin implants, the period of molting was shortened from 6 months (intact outdoor animals) to 4 months. 7. The advance in shedding was always related to an early drop in testosterone (or an absence of testosterone in the castrated animals) and to a higher or earlier increase in thyroxine levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Subfractionation of 1.006-1.063 g/ml components of badger plasma lipoproteins by using heparin-Sepharose affinity chromatography: relevance to the endocrine regulation of lipoprotein metabolism

Badger plasma lipoproteins with density 1.006-1.063 g/ml have been subfractionated by means of affinity chromatography on a heparin-Sepharose column, using a modification of the method reported by Weisgraber and Mahley (1980. J. Lipid Res. 21: 316-325). These experiments have provided evidence for the presence of three lipoprotein subfractions hereinafter termed fractions I, II, and III. Fraction I was cholesteryl ester- and phospholipid-rich (ca. 35% and 30% of lipoprotein mass, respectively), and contained apoA-I as its prominent apolipoprotein constituent. In contrast, triglyceride-rich fractions II and III both exhibited a complex apolipoprotein pattern, including apoB-100, apoA-I, and apoE whose amino acid composition and NH2-terminal sequence in the badger are reported. However, fraction III appeared markedly enriched in apoE when compared to fraction II. On polyacrylamide gel electrophoresis, fraction I presented as a spectrum of particles with diameters in the 140-190 A range. In contrast, fraction II migrated as a single band with a diameter of approximately 200 A, and fraction III presented as a single band or a doublet with a diameter of 195-200 A. The respective plasma concentrations and chemical compositions of the three chromatographic fractions were determined at four different dates of the year (i.e., April, August, November, and January), each of which corresponded to a different endocrine status in the badger. Thus hypothyroidism appeared to be associated with an increase in the concentration of fraction I, while the lowering in summer of the plasma level of testosterone correlated well with an increase in the concentration of fraction II. At the same time, the respective proportions of hydrophobic lipids in this latter material modified with an increase of triglycerides. Finally, both the apolipoprotein pattern of fraction III, and the chronologic profile of the successive variations of its concentration, suggest that it could represent a metabolic precursor of fraction II. These results suggest that the respective metabolism of the lipoproteins constituting the three chromatographic fractions could be under control by thyroid and testis secretions, operating via a complex combined regulation of the activities of the enzymes and receptors involved in these metabolic processes.

Thyroid and gonadal regulation of hair growth during the seasonal molt in the male European badger, Meles meles L

In the male badger we showed that hair growth and molt are related to plasma testosterone and thyroxine cycles. We established the action of testosterone by castration and subcutaneous testosterone implants, and the action of thyroxine by thyroidectomy and dietary supplementation with thyroxine. The following groups of animals were studied: controls, thyroidectomized, thyroidectomized and thyroxine-treated, castrated, castrated and thyroxine-treated, thyroidectomized and castrated and thyroxine-treated, castrated and testosterone-implanted, and intact testosterone-implanted. In control animals, molt and hair growth occurred during the summer, with a maximum growth in autumn. Molt ended at the beginning of winter when the plasma testosterone level had started to rise, and began again after this level had started to decline. Both the start of molt and the period of maximum hair growth coincided with high thyroxine levels of about 20 ng/ml. Castration advanced molt and hair follicle activity, whereas testosterone implants delayed both molt and hair growth. In thyroidectomized badgers, neither hair growth nor seasonal molt was observed. However, when thyroxine levels were restored to 20 ng/ml or more by dietary T4 supplementation, molting was resumed in animals that had undergone either thyroidectomy or thyroidectomy plus castration. In those that underwent castration only, the molt was advanced leading to early hair growth further stimulated by the suppression of testosterone. Testosterone had an inhibitory effect on the molt--since testosterone implants in intact control animals delayed it by 4 weeks--but did not inhibit it completely. On the other hand, a T4-enriched diet advanced the date of the molt. However, the molt could not be induced, nor could hair follicle growth be reactivated, at all times during the annual cycle. Thus, in castrated animals. T4 enrichment of the diet in early January, at the end of the molt, caused follicle reactivation only toward the end of May, despite the lack of testosterone. This 18-week latency period from January to May might therefore constitute a "refractory period" in this species. The above findings show that the regulation of the seasonal molt and hair growth in the European badger involves both the thyroid and genital axes. This regulation is discussed in terms of joint control by the hypothalamus and pituitary governed, in turn, by an external factor--the photoperiod--considered to be the main synchronizer.

A year-long study of changes induced by castration in the plasma lipid and lipoprotein spectrum in the European badger

In man, an influence of male sex hormones on plasma lipid transport is well established; however, recent data on this subject in the literature are both relatively lacking and occasionally conflicting. The male European badger exhibits seasonal variations of large amplitude in its gonadic function. We have therefore attempted to establish the influence of male sex steroids on plasma lipids and lipoproteins in this species. For this purpose, we have examined the plasma lipid and lipoprotein spectrum in a group of castrated male badgers every month for a year, non-operated animals being used as controls. Our analyses included measurement of plasma lipid levels, density gradient ultracentrifugation of lipoproteins, electrophoresis of lipoproteins and apolipoproteins, and evaluation of plasma testosterone and thyroxine levels. The differences observed between the 2 groups of animals were maximal during the months when plasma testosterone was elevated in intact badgers (January to July). For this period, castration resulted in higher plasma concentrations of cholesterol, phospholipids and triglycerides, while the latter alone remained significantly more elevated in operated animals until the end of our experiments. With regard to lipoproteins, the main effect of castration consisted of a large augmentation in the concentration of lipoproteins with d approximately equal to 1.027-1.065 g/ml which were responsible for the transport of most of the increased amounts of triglycerides present in the plasma of castrated badgers. The proportion of apoprotein B in the protein moiety of these lipoprotein components was enhanced after castration. Other changes in the lipoprotein spectrum included (1) a moderate increase in the concentration of lipoproteins with d less than 1.015 g/ml and 1.019-1.027 g/ml, and (2) a modification of the respective proportions of high density lipoproteins with d 1.065-1.100 g/ml and d 1.100-1.162 g/ml. Finally, no considerable differences between the 2 groups of animals were noted in the respective percentages of the various chemical constituents in each lipoprotein subfraction assayed, except for those with d 1.023-1.027 g/ml, which, in castrated badgers, did not exhibit the enrichment in triglycerides usually noted during late winter and spring in intact animals.

Isolation and characterization of the major plasma apolipoproteins, A-1 and B, in the European badger, Meles meles

The two major apolipoproteins of badger serum, apoA-I and apoB, have been isolated and characterized. Apolipoprotein A-I was the principal protein of badger lipoproteins with density 1.063-1.21 g/ml and, in addition, was present in the lipoprotein class with density 1.006-1.063 g/ml. This apolipoprotein displayed an Mr of approximately equal to 27,000-28,000 and was polymorphic (three prominent isoproteins) on isoelectric focusing, with pI values in the range 5.38-5.55. The amino acid profile of badger apoA-I generally resembled those reported in the literature for similar proteins in dog and man. Amino terminal sequence analysis up to the 40th residue showed close homology between the badger, dog, and human proteins; badger and dog apoA-I differed only at residue 24, at which serine in the dog was substituted by glycine in the badger. Several forms of apolipoprotein B were present in badger lipoproteins with densities less than 1.063 g/ml, their distribution and apparent Mr being unaffected by the presence or absence of 1 mM PMSF during the isolation process. The components of higher Mr were essentially represented by a protein with Mr approximately equal to 530,000-550,000 (apoBH) as determined by SDS-polyacrylamide electrophoresis; this protein predominated both in lipoproteins with d 1.006-1.063 g/ml and in those with d less than 1.006 g/ml. In addition, proteins with approximate Mr values of 490,000, 450,000, and 190,000, respectively, were present as minor components. A lower Mr form (250,000, apoBL), was observed only in lipoproteins with d less than 1.006 g/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

A year-long study of changes induced by thyroidectomy in the plasma lipid and lipoprotein spectrum in the European badger

Hypothyroidism is associated with hypercholesterolemia and increased risk for atherosclerotic disease. The European badger exhibits large seasonal changes in thyroid activity and the annual minimum of plasma thyroxine level in this species occurs at the same period of the year (i.e. late fall) as a pronounced hypercholesterolemia. We examined the plasma lipid and lipoprotein spectrum in a group of thyroidectomized male badgers every month for a year. Non-operated animals were used as controls. Our analyses included measurement of plasma lipid levels, density gradient ultracentrifugation of lipoproteins, electrophoresis of lipoproteins and apolipoproteins, and histological studies. Maximal differences between the two groups of animals were observed during spring, occurring concomitantly with the annual maximum of plasma thyroxine concentration in control badgers. Comparison with the latter animals revealed a permanent hypercholesterolemia and hyperphospholipidemia in thyroidectomized badgers, while their lipoprotein spectrum was characterized by the continual presence of elevated concentrations of cholesterol-rich lipoproteins of d congruent to 1.015 - 1.027 g/ml. The ratio of triglyceride/cholesteryl ester content in such lipoproteins remained constant throughout the year, resembling that noted in intact animals during late fall. Other features distinguishing the lipoprotein spectrum in thyroidectomized badgers were: (1) higher levels of lipoproteins with d 1.027 - 1.065 g/ml and d 1.065 - 1.100 g/ml, and (2) a cholesteryl ester enrichment of both these lipoprotein subclasses. The two groups of animals shared a heterogeneity of low density lipoprotein subfractions isolated on density gradients, together with the presence of apolipoproteins with molecular weights respectively typical of human apolipoproteins A-I and B throughout the low density range. Arterial walls and heart tissues from intact and thyroidectomized animals were free of atherosclerotic lesions at the end of the experimental period.

Seasonal reproductive endocrine profiles in two wild mammals: the red fox (Vulpes vulpes L.) and the European badger (Meles meles L.) considered as short-day mammals

The annual cycle of the testicular function (testis and epididymis weights and plasma testosterone levels) were considered in relation to seasonal variations in plasma LH and prolactin concentrations in two wild European mammals: the badger and the fox. Phase relationships were established between the annual prolactin cycles and daylight duration. The influence of castration on the seasonal variations in plasma LH levels was also studied. The resumption of activity in the testicular function occurs during autumn for both species. The reproduction period begins in winter but it is over by the beginning of spring for the fox whereas for the badger it lasts until early summer. In the same way, the annual cycle of the gonadotrophic function which, in the fox, presents only one maximum at the end of autumn, is bimodal in the badger with one maximum in January and a second in June. On the other hand, both species have a similar annual prolactin cycle, which shows an increase from the winter solstice onwards, in synchronization with the increase in daily light duration. The highest prolactin levels are measured in spring followed by a decrease during summer. This result calls into question the role played by prolactin in the regulation of the testicular function in as far as the two species have an annual reproductive cycle of the 'short-day' type (onset of activity occurring before the winter solstice) but show seasonal prolactin variations similar to those described for 'long-day' species.

[Season variations in lipolysis activity of adipocytes from fox, badger and hedgehog]

1. We have studied the seasonal variations of the lipolytic response to a beta agonist, isoproterenol, and to theophylline of the isolated adipocyte from fox, badger and hedgehog, related to the circannual variations of testes and thyroid activities. 2. With the fox, we find a coincidence, in spring, between the maximum lipolytic sensitivity of the adipocyte, the thyroid function and the return to sexual rest. 3. With the badger, in winter, the maximum reaction of the adipocyte is contemporary with testes activity and with thyroid rest. 4. With the hedgehog, we observe two maximums in the sensitivity of the adipocyte to the lipolytic agents, one in spring, which coincides with the maximal testes and thyroid activities, the other in autumn, before the deep hibernation state. 5. In conclusion, there is, with these wild mammals, a seasonal variation in the lipolytic reaction of adipocyte which coincides with that of energy needs.

Diet-induced and physiologically occurring hypercholesterolemias in the spontaneous hypothyroid European badger (Meles meles L.): a density gradient study of lipoprotein profile

As previously shown in this laboratory (Laplaud, P. M. et al. J. Lipid Res. 1980. 21: 724-738), the European badger is, with regard to its plasma lipid transport system, an original and complex animal of great potential interest to lipoprotein research. In an effort to study the response of this animal to cholesterol feeding, we gave a diet supplemented with 1% cholesterol to six male badgers (group H) during the late fall period when spontaneous hypercholesterolemia and hypothyroidism occur. Six more male animals of similar age received the standard diet (group C) and were simultaneously used as controls. Plasma lipids were measured using enzymatic methodologies, while the use of a recently described density gradient ultracentrifugation technique allowed detailed examination of lipoprotein composition and polyacrylamide gel electrophoresis of lipoproteins and tetramethylurea-soluble apoproteins in the fractions. The results suggest the superimposition, in H badgers, of the spontaneous and diet-induced hypercholesterolemias, maximum levels being reached in December in both C and H groups. While the two groups were very similar at the beginning of the experiment, highly significant differences (P < 0.01) were subsequently observed between C and H animals in plasma cholesterol and phospholipid concentrations. Density gradient ultracentrifugation provided evidence for the following diet-induced changes in lipoprotein profile: 1) a twofold increase in cholesteryl esters in particles of d < 1.006 g/ml; 2) the occurrence of large amounts of supplementary cholesterol-rich low density lipoproteins, mainly in the 1.019-1.027 g/ml region; 3) an increase in the 1.039-1.055 g/ml low density lipoproteins; and 4) a change in the ratio of the concentrations of high density lipoproteins of d 1.065-1.100 g/ml and d 1.100-1.162 g/ml, to the benefit of the former. Electrophoresis of the density gradient fractions revealed marked heterogeneity, especially in the low density part of the spectrum. Electrophoresis of the low molecular weight, tetramethylurea-soluble apoproteins failed to show marked differences between C and H badgers. However, chromatographic determination of the proportion of apoB in the protein moiety of the two main low density components showed that 1) it was consistently low, 2) its contribution to the higher density fraction (d 1.039-1.046 g/ml) was unaffected by the hypercholesterolemic diet (being about 25% in both C and H animals), and 3) its contribution to the lower density fraction (d 1.019-1.027 g/ml) decreased under the same nutritional conditions, representing about 20% in C as compared to about 10% in H badgers.-Laplaud, P. M., Beaubatie, and D. Maurel. Dietinduced and physiologically occurring hypercholesterolemias in the spontaneous hypothyroid European badger (Meles meles L.): a density gradient study of lipoprotein profile.

Further characterization of the changes occurring in the plasma lipoprotein spectrum in the European badger (Meles meles L.) during winter

The plasma lipoprotein pattern in the European badger has been shown previously to undergo marked and complex quantitative and qualitative seasonal modifications (Laplaud, P.M. et al., 1980, J. Lipid Res., 21, 724-738). However, the conventional ultracentrifugal techniques then in use in our laboratory were of insufficient discriminating power with regard to the numerous lipoprotein fractions whose presence was suggested by our analyses. In the present study, a new density gradient ultracentrifugation procedure was applied to the more detailed determination of the distribution of plasma lipoproteins. The first series of analyses was performed in early December and the second in March, i.e. at the dates when the maximum and minimum, respectively, of lipidemia occur in this species. The fractions thus obtained, each of which corresponded to a narrow density interval, were analyzed subsequently for chemical composition, appearance upon polyacrylamide gel electrophoresis, and for their content of tetramethylurea-soluble apolipoproteins in alkaline-urea gels. Changes occurring from December to March included a large decrease in the plasma concentration of the 1.015-1.065 g/ml lipoproteins, chemical analysis of this material being compatible with the presence of at least two lipoprotein populations. On the other hand, high-density lipoproteins (1.065-1.162 g/ml) appeared less variable in chemical composition, although the proportion of those with lower density decreased considerably in early spring. Polyacrylamide gel electrophoresis of the native fractions showed multiple bands in most of them; the tetramethylurea-soluble apoprotein profile remained similar at the two dates considered with an apolipoprotein A-I-like component present in large amounts throughout the entire low- and high-density ranges.

Métabolisme périphérique de la testostérone en relation avec le cycle annuel de la testostérone et de la 5α-dihydrotestostérone plasmatiques chez le Blaireau européen (Meles meles L.) et le Renard roux (Vulpes vulpes L.)

Seasonal variations in plasma contents of testosterone, 5α-dihydrotestosterone (5α-DHT) and other parameters related to the peripheral metabolism of testosterone have been determined in adult foxes and badgers, in natural climatic conditions.In both species, testosterone reaches peak levels in winter, but whereas the fox takes a sexual break beginning in spring (April), the badger has high concentrations of hormones until the summer. The mean annual concentration of testosterone is four times higher in the badger than in the fox; the annual mean value of 5α-dihydrotestosterone is identical in both species and levels of 5α-DHT are significantly higher during the breeding period.The annual cycle of testosterone peripheral metabolism in the fox is characterized by a decreased rate during summer and fall and an increased rate during winter (breeding period). In the badger, the metabolic clearance rate is high at the end of the fall and at the onset of the breeding period (October to January) and low during the peak reproduction period (February to April) and then increases as the period of sexual break approaches.The annual cycle of testosterone production rate is characterized in both species by a fall or prewinter increase; in the fox, this increase is followed by a decrease at the end of the winter, whereas the badger keeps pretty well the same rate of production until the summer.Seasonal variations of hormone peripheral metabolism are examined and discussed in relation to the fluctuations in testosterone levels and the hormone-specific protein linkage capacity.[Journal Translation]

Seasonal variations in thyroxine and testosterone levels in relation to the moult in the adult male mink (Mustela vison Peale and Beauvois)

Plasma thyroxine (T4) and testosterone concentrations were measured in adult male mink maintained outdoors under natural light and fed ad libitum the whole year round. Plasma T4 concentrations presented a biphasic seasonal change, the highest values occurring in the spring and autumn months and the lowest values in the winter months. The plasma testosterone cycle showed an annual maximum in January–February. The possibility of testis–thyroid interactions is discussed. The changes observed are correlated with environmental temperature, photoperiod, and molting cycle.

Short-term variations of plasma testosterone concentrations in the European badger (Meles meles)

Badgers were sampled once during the sexually inactive season (July-November) and during the breeding season (February-April) and testosterone and dihydrotestosterone (DHT) concentrations were measured by radioimmunoassay after separation by chromatography. Concentrations of both hormones were higher in the breeding than non-breeding season, but the mean ratio of testosterone to DHT was greater in the breeding (14) than in the non-breeding season (7). During the breeding season (March 1979) 18 adult male badgers were bled at 12-min intervals for 3 h over a period of 24 h. Testosterone concentrations were measured without chromatography. An episodic pattern of release was observed. All the animals exhibited peaks of large amplitude (1-30 ng/ml) which lasted for about 2 h. The great variability in mean testosterone values for each animal (1-13 ng/ml) could also have been due to differences in individual sexual status.