Emergence and dissemination of three mild outbreaks of Neisseria gonorrhoeae with high-level resistance to azithromycin in Barcelona, 2016-18.

BACKGROUND: Neisseria gonorrhoeae (NG) isolates with high-level azithromycin resistance (HL-AziR) have emerged worldwide in recent decades, threatening the sustainability of current dual-antimicrobial therapy. OBJECTIVES: This study aimed to characterize the first 16 NG isolates with HL-AziR in Barcelona between 2016 and 2018. METHODS: WGS was used to identify the mechanisms of antimicrobial resistance, to establish the MLST ST, NG multiantigen sequence typing (NG-MAST) ST and NG sequence typing for antimicrobial resistance (NG-STAR) ST and to identify the clonal relatedness of the isolates with other closely related NG previously described in other countries based on a whole-genome SNP analysis approach. The sociodemographic characteristics of the patients included in the study were collected by comprehensive review of their medical records. RESULTS: Twelve out of 16 HL-AziR isolates belonged to the MLST ST7823/NG-MAST ST5309 genotype and 4 to MLST ST9363/NG-MAST ST3935. All presented the A2059G mutation in all four alleles of the 23S rRNA gene. MLST ST7823/NG-MAST ST5309 isolates were only identified in men who have sex with women and MLST ST9363/NG-MAST ST3935 were found in MSM. Phylogenomic analysis revealed the presence of three transmission clusters of three different NG strains independently associated with sexual behaviour. CONCLUSIONS: Our findings support the first appearance of three mild outbreaks of NG with HL-AziR in Spain. These results highlight the continuous capacity of NG to develop antimicrobial resistance and spread among sexual networks. The enhanced resolution of WGS provides valuable information for outbreak investigation, complementing the implementation of public health measures focused on the prevention and dissemination of MDR NG.

Circadian glucocorticoid oscillations preserve a population of adult hippocampal neural stem cells in the aging brain.

A decrease in adult hippocampal neurogenesis has been linked to age-related cognitive impairment. However, the mechanisms involved in this age-related reduction remain elusive. Glucocorticoid hormones (GC) are important regulators of neural stem/precursor cells (NSPC) proliferation. GC are released from the adrenal glands in ultradian secretory pulses that generate characteristic circadian oscillations. Here, we investigated the hypothesis that GC oscillations prevent NSPC activation and preserve a quiescent NSPC pool in the aging hippocampus. We found that hippocampal NSPC populations lacking expression of the glucocorticoid receptor (GR) decayed exponentially with age, while GR-positive populations decayed linearly and predominated in the hippocampus from middle age onwards. Importantly, GC oscillations controlled NSPC activation and GR knockdown reactivated NSPC proliferation in aged mice. When modeled in primary hippocampal NSPC cultures, GC oscillations control cell cycle progression and induce specific genome-wide DNA methylation profiles. GC oscillations induced lasting changes in the methylation state of a group of gene promoters associated with cell cycle regulation and the canonical Wnt signaling pathway. Finally, in a mouse model of accelerated aging, we show that disruption of GC oscillations induces lasting changes in dendritic complexity, spine numbers and morphology of newborn granule neurons. Together, these results indicate that GC oscillations preserve a population of GR-expressing NSPC during aging, preventing their activation possibly by epigenetic programming through methylation of specific gene promoters. Our observations suggest a novel mechanism mediated by GC that controls NSPC proliferation and preserves a dormant NSPC pool, possibly contributing to a neuroplasticity reserve in the aging brain.

Implementation of pre-harvest techniques in emerging agroforestry systems to increase the yield of cocoa tree (Theobroma cacao L.).

Cocoa is one of the most important tropical fruits worldwide, its importance lies in its use in the food, cosmetic and pharmaceutical industries. Cocoa yield has been affected by different environmental, cultural and phytosanitary aspects. The emergence of new growing areas allows exploring the possibility of generating new economic and ecological systems that comply with current trends in organic farming. For them, pre-harvest practices such as pruning and soil fertilization are two necessary tools to control the productivity of cocoa agroecosystems. Therefore, the objective of this research was to analyses the implementation of pre-harvest techniques and the quality soil to increase the yield in a cocoa agroecosystem in an emerging zone in the Huasteca Potosina of Mexico. The work was carried out in an emerging zone in the cultivation of cocoa in three different zones delimited in 30 × 30 m. Thinning and pruning practices were carried out to keep the space clear and observe the influence on fruit yield. In addition, the quality of the soil was measured in terms of physical conditions and nutrient content. 25 kg/ha of nitrogen, 22 kg/ha of P2O5, 24 kg/ha of K2O and 4 kg/ha of magnesium were added following the recommendation of the fertilization laboratory. The physical properties of the pod were also analyzed, such as size, weight, number of grains and color. And some of the cocoa bean such as size, weight and hardness, all these parameters to measure the average yield of cocoa pods. The results show a clear influence of the soil quality and pre-harvest practices on the physical properties of the fruit and the total yield from 472.36 ± 52.01 to 520.06 ± 104.91 kg. However, other aspects are also modified, such as the increase in the size of the pod and the cocoa bean. Other aspects such as the color of the pod and the hardness of the grain do not present statistical difference. In conclusion, pre-harvest practices together with the application of fertilizers are factors that positively influence the yield of cocoa fruit. Some of the limitations of this research were the age of the plants and the local plant species.

Serum insulin-like growth factor I regulates brain amyloid-beta levels.

Levels of insulin-like growth factor I (IGF-I), a neuroprotective hormone, decrease in serum during aging, whereas amyloid-beta (Abeta), which is involved in the pathogenesis of Alzheimer disease, accumulates in the brain. High brain Abeta levels are found at an early age in mutant mice with low circulating IGF-I, and Abeta burden can be reduced in aging rats by increasing serum IGF-I. This opposing relationship between serum IGF-I and brain Abeta levels reflects the ability of IGF-I to induce clearance of brain Abeta, probably by enhancing transport of Abeta carrier proteins such as albumin and transthyretin into the brain. This effect is antagonized by tumor necrosis factor-alpha, a pro-inflammatory cytokine putatively involved in dementia and aging. Because IGF-I treatment of mice overexpressing mutant amyloid markedly reduces their brain Abeta burden, we consider that circulating IGF-I is a physiological regulator of brain amyloid levels with therapeutic potential.

The role of connectivity on COVID-19 preventive approaches.

Preventive and modelling approaches to address the COVID-19 pandemic have been primarily based on the age or occupation, and often disregard the importance of heterogeneity in population contact structure and individual connectivity. To address this gap, we developed models based on Erdos-Rényi and a power law degree distribution that first incorporate the role of heterogeneity and connectivity and then can be expanded to make assumptions about demographic characteristics. Results demonstrate that variations in the number of connections of individuals within a population modify the impact of public health interventions such as lockdown or vaccination approaches. We conclude that the most effective strategy will vary depending on the underlying contact structure of individuals within a population and on timing of the interventions.

A toolbox for the longitudinal assessment of healthspan in aging mice.

The number of people aged over 65 is expected to double in the next 30 years. For many, living longer will mean spending more years with the burdens of chronic diseases such as Alzheimer's disease, cardiovascular disease, and diabetes. Although researchers have made rapid progress in developing geroprotective interventions that target mechanisms of aging and delay or prevent the onset of multiple concurrent age-related diseases, a lack of standardized techniques to assess healthspan in preclinical murine studies has resulted in reduced reproducibility and slow progress. To overcome this, major centers in Europe and the United States skilled in healthspan analysis came together to agree on a toolbox of techniques that can be used to consistently assess the healthspan of mice. Here, we describe the agreed toolbox, which contains protocols for echocardiography, novel object recognition, grip strength, rotarod, glucose tolerance test (GTT) and insulin tolerance test (ITT), body composition, and energy expenditure. The protocols can be performed longitudinally in the same mouse over a period of 4-6 weeks to test how candidate geroprotectors affect cardiac, cognitive, neuromuscular, and metabolic health.

Inhibition of adult hippocampal neurogenesis disrupts contextual learning but spares spatial working memory, long-term conditional rule retention and spatial reversal.

Neurogenesis in the adult dentate gyrus (DG) of the hippocampus has been implicated in neural plasticity and cognition but the specific functions contributed by adult-born neurons remain controversial. Here, we have explored the relationship between adult hippocampal neurogenesis and memory function using tasks which specifically require the participation of the DG. In two separate experiments several groups of rats were exposed to fractionated ionizing radiation (two sessions of 7 Gy each on consecutive days) applied either to the whole brain or focally, aiming at a region overlying the hippocampus. The immunocytochemical assays showed that the radiation significantly reduced the expression of doublecortin (DCX), a marker for immature neurons, in the dorsal DG. Ultrastructural examination of the DG region revealed disruption of progenitor cell niches several weeks after the radiation. In the first experiment, whole-brain and focal irradiation reduced DCX expression by 68% and 43%, respectively. Whole-brain and focally-irradiated rats were unimpaired compared with control rats in a matching-to-place (MTP) working memory task performed in the T-maze and in the long-term retention of the no-alternation rule. In the second experiment, focal irradiation reduced DCX expression by 36% but did not impair performance on (1) a standard non-matching-to-place (NMTP) task, (2) a more demanding NMTP task with increasingly longer within-trial delays, (3) a long-term retention test of the alternation rule and (4) a spatial reversal task. However, rats irradiated focally showed clear deficits in a "purely" contextual fear-conditioning task at short and long retention intervals. These data demonstrate that reduced adult hippocampal neurogenesis produces marked deficits in the rapid acquisition of emotionally relevant contextual information but spares spatial working memory function, the long-term retention of acquired spatial rules and the ability to flexibly modify learned spatial strategies.

The hippocampal dentate gyrus is essential for generating contextual memories of fear and drug-induced reward.

The hippocampus is believed to play a role in processing information relative to the context in which emotionally salient experiences occur but evidence on the specific contribution of the hippocampal dentate gyrus (DG) to these processes is limited. Here, we have used two classical behavioral paradigms to study the participation of the dorsal DG in context-conditioned reward and context-conditioned fear. Rats received intra-hippocampal vehicle or colchicine injections (4 microg/microl solution; 0.2 microl injections at 10 sites) that damaged the DG but spared other hippocampal subfields. In the first experiment, we used a place conditioning procedure pairing cocaine exposure (20 mg/kg, i.p.) with a specific context and vehicle treatment with another. While rats with sham lesions exhibited preference for the cocaine-paired context following conditioning, rats with lesions of the DG showed no evidence of cocaine-induced place preference. In the second experiment, rats with sham or colchicine lesions received a foot shock in a given context and conditioned freezing was measured upon reexposure to the shock-paired context (2, 24, 48 and 96 h after conditioning). Rats with sham lesions exhibited high levels of conditioned freezing when exposed to the conditioning context but rats with lesions of the DG showed impaired conditioning, behaving as controls that had experienced shock in a different context. These observations indicate that the integrity of the DG is essential for establishing a coherent representation of the context to which emotional experiences, either hedonic or aversive, are bound.

Human Ste20 homologue hPAK1 links GTPases to the JNK MAP kinase pathway.

BACKGROUND: The Rho-related GTP-binding proteins Cdc42 and Rac1 have been shown to regulate signaling pathways involved in cytoskeletal reorganization and stress-responsive JNK (Jun N-terminal kinase) activation. However, to date, the GTPase targets that mediate these effects have not been identified. PAK defines a growing family of mammalian kinases that are related to yeast Ste20 and are activated in vitro through binding to Cdc42 and Rac1 (PAK: p21 Cdc42-/Rac-activated kinase). Clues to PAK function have come from studies of Ste20, which controls the activity of the yeast mating mitogen-activated protein (MAP) kinase cascade, in response to a heterotrimeric G protein and Cdc42. RESULTS: To initiate studies of mammalian Ste20-related kinases, we identified a novel human PAK isoform, hPAK1. When expressed in yeast, hPAK1 was able to replace Ste20 in the pheromone response pathway. Chemical mutagenesis of a plasmid encoding hPAK1, followed by transformation into yeast, led to the identification of a potent constitutively active hPAK1 with a substitution of a highly conserved amino-acid residue (L107F) in the Cdc42-binding domain. Expression of the hPAK1(L107F) allele in mammalian cells led to specific activation of the Jun N-terminal kinase MAP kinase pathway, but not the mechanistically related extracellular signal-regulated MAP kinase pathway. CONCLUSIONS: These results demonstrate that hPAK1 is a GTPase effector controlling a downstream MAP kinase pathway in mammalian cells, as Ste20 does in yeast. Thus, PAK and Ste20 kinases play key parts in linking extracellular signals from membrane components, such as receptor-associated G proteins and Rho-related GTPases, to nuclear responses, such as transcriptional activation.

Both increases in immature dentate neuron number and decreases of immobility time in the forced swim test occurred in parallel after environmental enrichment of mice.

A direct relation between the rate of adult hippocampal neurogenesis in mice and the immobility time in a forced swim test after living in an enriched environment has been suggested previously. In the present work, young adult mice living in an enriched environment for 2 months developed considerably more immature differentiating neurons (doublecortin-positive, DCX(+)) than control, non-enriched animals. Furthermore, we found that the more DCX(+) cells they possessed, the lower the immobility time they scored in the forced swim test. This DCX(+) subpopulation is composed of mostly differentiating dentate neurons independently of the birthdates of every individual cell. However, variations found in this subpopulation were not the result of a general effect on the survival of any newborn neuron in the granule cell layer, as 5-bromo-2-deoxyuridine (BrdU)-labeled cells born during a narrow time window included in the longer lifetime period of DCX(+) cells, were not significantly modified after enrichment. In contrast, the survival of the mature population of neurons in the granule cell layer of the dentate gyrus in enriched animals increased, although this did not influence their performance in the Porsolt test, nor did it influence the dentate gyrus volume or granule neuronal nuclei size. These results indicate that the population of immature, differentiating neurons in the adult hippocampus is one factor directly related to the protective effect of an enriched environment against a highly stressful event.

Biphasic increase in c-jun mRNA is required for induction of AP-1-mediated gene transcription: differential effects of muscarinic and thrombin receptor activation.

Activation of either muscarinic cholinergic or thrombin receptors increases phosphoinositide turnover, Ca2+ mobilization, and redistribution of protein kinase C and induces rapid transient increases in c-fos mRNA and c-jun mRNA in 1321N1 cells. To determine whether the increases in c-fos and c-jun mRNA induced by carbachol and thrombin are sufficient to stimulate AP-1-mediated transactivation, 1321N1 cells were transfected with a reporter carrying two copies of the tetradecanoyl phorbol acetate response element and the firefly luciferase gene. Thrombin was significantly more effective than carbachol at stimulating AP-1-mediated transactivation. To identify the factors underlying the difference in AP-1 activity induced by carbachol and thrombin, members of the fos and jun families which encode components of AP-1 were examined. Carbachol and thrombin have similar effects on expression of c-fos, fosB, fra-2, junB, and junD, both acutely and over a 24-h time course. However, whereas carbachol leads only to transient induction of c-jun (maximal at 0.5 h), thrombin induces a biphasic increase in c-jun mRNA--an initial peak at 0.5 h and a second, more-prolonged increase at 12 h. Thrombin but not carbachol also induces a late increase in fra-1 mRNA, which peaks at 12 h. The secondary increase in c-jun mRNA is associated with marked increases in c-Jun protein levels and AP-1 DNA-binding activity. The late induction of c-jun and fra-1 mRNA can be prevented by adding the antagonist hirudin 30 min after thrombin, which results in loss of thrombin-stimulated increases in c-Jun protein, AP-1 DNA-binding activity, and AP-1-mediated transactivation. These findings suggest that rapid and transient conduction of c-fos and c-jun mRNA is insufficient to induce prominent changes in gene transcription, while the sustained increase in c-jun mRNA and perhaps the late induction of fra-1 mRNA are required for generation of AP-1 DNA-binding activity and transactivation through AP-1.

Spared place and object-place learning but limited spatial working memory capacity in rats with selective lesions of the dentate gyrus.

We studied the cognitive performance of rats with colchicine-induced lesions of the hippocampal dentate gyrus (DG) on a range of spatial, non-spatial and mixed spatial/procedural tasks. Rats were assigned to three experimental groups receiving large colchicine lesions (7 microg per hippocampus), small colchicine lesions (1.75 microg per hippocampus) or sham lesions. Stereological estimates of cell density indicated that the colchicine treatments induced dose-dependent damage to the DG, while sparing in large part other hippocampal subfields. Remarkably, the behavioural results showed that the colchicine lesions did not affect the performance of rats in an object discrimination task, in an object-place associative task in which a familiar object was displaced from a given position nor in a spontaneous spatial discrimination task performed in the T-maze. However, rats in both lesion groups were severely impaired in a reinforced non-matching-to-position working memory task conducted in the T-maze. Importantly, performance in the working memory task correlated strongly with cell density in the DG but not with cell density in the CA1 and CA3 areas. Only rats with large-lesions showed a transient deficit in a reinforced rule-based conditional discrimination task. These data demonstrated that rats with selective lesions of the DG readily acquire and retain neural representations relative to objects and places but are specifically impaired in their ability to update rapidly and flexibly spatial information that is essential to guide goal-directed actions.

Protostrongylid parasites and pneumonia in captive and wild thinhorn sheep (Ovis dalli).

We describe health significance of protostrongylid parasites (Parelaphostrongylus odocoilei and Protostrongylus stilesi) and other respiratory pathogens in more than 50 naturally infected Dall's sheep (Ovis dalli dalli) from the Mackenzie Mountains, Northwest Territories (1998-2002) as well as in three Stone's sheep (O. d. stonei) experimentally infected with P. odocoilei (2000-2002). Histological lesions in the brain and distribution of P. odocoilei in the muscles of experimentally and naturally infected sheep were consistent with a previously hypothesized "central nervous system to muscle" pattern of migration for P. odocoilei. Dimensions of granulomas associated with eggs of P. odocoilei and density of protostrongylid eggs and larvae in the cranial lung correlated with intensity of larvae in feces, and all varied with season of collection. Prevalence of P. stilesi based on the presence of larvae in feces underestimated true prevalence (based on examination of lungs) in wild Dall's sheep collected in summer and fall. Similarly, counts of both types of protostrongylid larvae in feces were unreliable indicators of parasitic infection in wild Dall's sheep with concomitant bacterial pneumonia associated with Arcanobacterium pyogenes, Pasteurella sp., and Mannheimia sp. Diffuse, interstitial pneumonia due to P. odocoilei led to fatal pulmonary hemorrhage and edema after exertion in one experimentally infected Stone's sheep and one naturally infected Dall's sheep. Bacterial and verminous pneumonia associated with pathogens endemic in wild Dall's sheep in the Mackenzie Mountains caused sporadic mortalities. There was no evidence of respiratory viruses or bacterial strains associated with domestic ruminants, from which this population of wild sheep has been historically isolated.

14-3-3 Proteins regulate Akt Thr308 phosphorylation in intestinal epithelial cells.

Akt activation has been associated with proliferation, differentiation, survival and death of epithelial cells. Phosphorylation of Thr308 of Akt by phosphoinositide-dependent kinase 1 (PDK1) is critical for optimal stimulation of its kinase activity. However, the mechanism(s) regulating this process remain elusive. Here, we report that 14-3-3 proteins control Akt Thr308 phosphorylation during intestinal inflammation. Mechanistically, we found that IFNγ and TNFα treatment induce degradation of the PDK1 inhibitor, 14-3-3η, in intestinal epithelial cells. This mechanism requires association of 14-3-3ζ with raptor in a process that triggers autophagy and leads to 14-3-3η degradation. Notably, inhibition of 14-3-3 function by the chemical inhibitor BV02 induces uncontrolled Akt activation, nuclear Akt accumulation and ultimately intestinal epithelial cell death. Our results suggest that 14-3-3 proteins control Akt activation and regulate its biological functions, thereby providing a new mechanistic link between cell survival and apoptosis of intestinal epithelial cells during inflammation.

Circulating insulin-like growth factor I mediates exercise-induced increases in the number of new neurons in the adult hippocampus.

Although the physiological significance of continued formation of new neurons in the adult mammalian brain is still uncertain, therapeutic strategies aimed to potentiate this process show great promise. Several external factors, including physical exercise, increase the number of new neurons in the adult hippocampus, but underlying mechanisms are not yet known. We recently found that exercise stimulates uptake of the neurotrophic factor insulin-like growth factor I (IGF-I) from the bloodstream into specific brain areas, including the hippocampus. In addition, IGF-I participates in the effects of exercise on hippocampal c-fos expression and mimics several other effects of exercise on brain function. Because subcutaneous administration of IGF-I to sedentary adult rats markedly increases the number of new neurons in the hippocampus, we hypothesized that exercise-induced brain uptake of blood-borne IGF-I could mediate the stimulatory effects of exercise on the adult hippocampus. Thus, we blocked the entrance of circulating IGF-I into the brain by subcutaneous infusion of a blocking IGF-I antiserum to rats undergoing exercise training. The resulting inhibition of brain uptake of IGF-I was paralleled by complete inhibition of exercise-induced increases in the number of new neurons in the hippocampus. Exercising rats receiving an infusion of nonblocking serum showed normal increases in the number of new hippocampal neurons after exercise. Thus, increased uptake of blood-borne IGF-I is necessary for the stimulatory effects of exercise on the number of new granule cells in the adult hippocampus. Taken together with previous results, we conclude that circulating IGF-I is an important determinant of exercise-induced changes in the adult brain.

Circulating insulin-like growth factor I mediates the protective effects of physical exercise against brain insults of different etiology and anatomy.

Physical exercise ameliorates age-related neuronal loss and is currently recommended as a therapeutical aid in several neurodegenerative diseases. However, evidence is still lacking to firmly establish whether exercise constitutes a practical neuroprotective strategy. We now show that exercise provides a remarkable protection against brain insults of different etiology and anatomy. Laboratory rodents were submitted to treadmill running (1 km/d) either before or after neurotoxin insult of the hippocampus (domoic acid) or the brainstem (3-acetylpyridine) or along progression of inherited neurodegeneration affecting the cerebellum (Purkinje cell degeneration). In all cases, animals show recovery of behavioral performance compared with sedentary ones, i.e., intact spatial memory in hippocampal-injured mice, and normal or near to normal motor coordination in brainstem- and cerebellum-damaged animals. Furthermore, exercise blocked neuronal impairment or loss in all types of injuries. Because circulating insulin-like growth factor I (IGF-I), a potent neurotrophic hormone, mediates many of the effects of exercise on the brain, we determined whether neuroprotection by exercise is mediated by IGF-I. Indeed, subcutaneous administration of a blocking anti-IGF-I antibody to exercising animals to inhibit exercise-induced brain uptake of IGF-I abrogates the protective effects of exercise in all types of lesions; antibody-treated animals showed sedentary-like brain damage. These results indicate that exercise prevents and protects from brain damage through increased uptake of circulating IGF-I by the brain. The practice of physical exercise is thus strongly recommended as a preventive measure against neuronal demise. These findings also support the use of IGF-I as a therapeutical aid in brain diseases coursing with either acute or progressive neuronal death.

Plasma dehydroepiandrosterone and dehydroepiandrosterone sulfate in patients undergoing diagnostic coronary angiography.

Serum levels of DHEA sulfate are inversely associated with cardiovascular death in men, and urinary dehydroepiandrosterone (DHEA) levels are inversely associated with clinical manifestations of coronary artery disease. These observations may be related to the antiproliferative effects of DHEA, resulting in inhibition of atherosclerotic intimal hyperplasia. To examine the relation between these steroids and a direct measure of coronary atherosclerosis, plasma DHEA and DHEA sulfate levels were determined in 206 middle-aged patients (103 men, 103 women) undergoing elective coronary angiography. Plasma DHEA sulfate levels were lower in men with at least one stenosis greater than or equal to 50% compared with those without any stenosis greater than or equal to 50% (4.9 +/- 2.7 versus 6.1 +/- 3.5 nmol/ml, p = 0.05). Levels of DHEA sulfate were also inversely related to the number of diseased coronary vessels (r = -0.20, p = 0.05) and a continuous measure of the extent of coronary atherosclerosis (r = -0.25, p = 0.01) in men. The association between DHEA sulfate levels and extent of coronary artery disease was independent of age and other conventional risk factors for coronary disease. In women, there was no association between plasma DHEA or DHEA sulfate levels and coronary disease. These data demonstrate a consistent, independent, inverse, dose-response relation between plasma DHEA sulfate levels and angiographically defined coronary atherosclerosis in men. Plasma DHEA sulfate may be another important and potentially modifiable risk factor for the development and progression of coronary atherosclerosis.

Estrogen receptors and insulin-like growth factor-I receptors mediate estrogen-dependent synaptic plasticity.

Previous studies have shown that estradiol induces a transient disconnection of axo-somatic inhibitory synapses in the hypothalamic arcuate nucleus of adult ovariectomized rats. The synaptic disconnection is accompanied by an increase in the levels of insulin-like growth factor-I (IGF-I) in the arcuate nucleus, suggesting that IGF-I signaling may be involved in the estrogen-induced synaptic plasticity. The role of estrogen receptors and IGF-I receptors in the synaptic changes has been studied by assessing the number of axo-somatic synapses in ovariectomized rats treated with intracerebroventricular administration of the estrogen receptor antagonist ICI 182,780 and the IGF-I receptor antagonist JBI to ovariectomized rats. Estradiol administration resulted in a significant decrease in the number of axo-somatic synapses on arcuate neurons in control ovariectomized rats. Both the estrogen receptor antagonist and the IGF-I receptor antagonist blocked the estrogen-induced synaptic decrease. This finding suggest that estrogen-induced synaptic plasticity in the arcuate nucleus is dependent on the activation of both estrogen receptors and IGF-I receptors.

Calbindin-D28k- and astroglial protein-immunoreactivities, and ultrastructural differentiation in the prenatal rat cerebral cortex and hippocampus are affected by maternal adrenalectomy.

Maternal adrenal steroid hormones have been proven to be crucial for lung and adrenal prenatal maturation. These hormones mediate the effects of prenatal stress crossing the placenta and influencing the development of the hypothalamus-pituitary-adrenal axis of fetuses. In the present study, we have compared the prenatal development of fetuses from adrenalectomized mothers (ADX group) and from sham-operated mothers. We have used immunohistochemistry for calcium binding-protein Calbindin-D28k, astroglial proteins vimentin and glial fibrillary acidic protein (GFAP), and the ultrastructural differentiation of the cerebral cortex and hippocampus to measure putative differences. The ontogeny of the Calbindin-D28k immunoreactivity was delayed, as transient Calbindin-positive neuronal populations in the ADX group disappeared later during development as compared to that of control animals both in cerebral cortex and hippocampus; cell counts revealed that ADX animals had a significantly higher number of Calbindin-positive cells than controls in the cerebral cortex, while that number was lower in ADX fetuses' hippocampus. Cerebral cortex of ADX animals also had a scattered distribution of stained cells compared with controls, while the hippocampi of the ADX animals had an impaired migration of marginal zone interneurons. No GFAP immunoreactivity was found in the studied prenatal stages. Instead, vimentin-immunoreactivity appeared more profusely distributed throughout the cerebral cortex, in the ADX group than in control animals. At the ultrastructural level, no remarkable differences were found before E20, when a higher undifferentiation in the ADX group, in both cerebral cortex and hippocampus, was evident. The results show for the first time the vulnerability of the prenatal rat brain to maternal adrenalectomy and the necessity of maternal glucocorticoids for encephalic development.