Role of α-CGRP in the regulation of neurotoxic responses induced by kainic acid in mice

Kainic acid (KA) is an excitatory and neurotoxic substance. The role of α-calcitonin gene-related peptide (α-CGRP) in the regulation of KA-induced hippocampal neuronal cell death was investigated in the present study. The intracerebroventricular (i.c.v.) administration with KA (0.07 μg) increased hippocampal α-CGRP mRNA level in ICR mice. The α-CGRP mRNA level began to increase at 1 h, reached at maximal level at 6 and 12 h, and returned to the control level by 24 h after i.c.v. administration with KA. In addition, KA-induced hippocampal CA3 neuronal death in C57BL6 (wild type) group was more pronounced compared to KA-induced hippocampal CA3 pyramidal cell death in α-CGRP knock-out (KO) group. Furthermore, sumatriptan, a CGRP releasing inhibitor, significantly protected the pyramidal cell death in CA3 hippocampal region induced by KA administered i.c.v. in ICR mice. Our results suggest that α-CGRP may play an important role in the regulation of KA-induced pyramidal cell death in CA3 region of the hippocampus.     

The characteristics of therapeutic effect of pinocembrin in transient global brain ischemia/reperfusion rats

AimsThe therapeutic effect of pinocembrin, together with the therapeutic time window, in the transient global cerebral ischemia/reperfusion (I/R) rats was investigated.Main methodsAdult male Sprague–Dawley rats were subjected to global cerebral ischemia for 20 min by four-vessel occlusion. Pinocembrin (1 and 5 mg/kg) was administrated intravenously 30 min before ischemia and 30 min, 2 h, 6 h after reperfusion, respectively. Neurological scores, brain edema and histological examination by Nissl staining were employed to assess the neuronal injury after ischemia and the neuroprotection by pinocembrin. The activities of superoxide dismutase (SOD), myeloperoxidase (MPO) and the content of malondialdehyde (MDA) in brain tissue were tested by colorimetric assays. Alterations of neurotransmitters were determined by a high performance liquid chromatography–electrochemical method.Key findingsPinocembrin significantly ameliorated neurological deficits and brain edema, and alleviated the degree of hippocampal neuronal loss at 24 h after global cerebral I/R with a broad therapeutic time window. It was found that treatment with pinocembrin reduced the compensatory increase of SOD activity and decreased the MDA level and MPO activity in a dose-dependent manner. The metabolic balance between excitatory and inhibitory amino acids was modulated by pinocembrin treatment.SignificanceThese findings suggest that pinocembrin provides neuroprotection against global cerebral ischemic injury with a wide therapeutic time window, which may be attributed to its antioxidative, antiinflammatory and antiexcitotoxic effects.     

Effect of sevoflurane and halothane anesthesia on cognitive function and immune function in young rats

In the current study, we scrutinized the effect of sevoflurane and halothane on cognitive and immune function in young rats. The rats were divided into following groups: sevoflurane, halothane and sevoflurane + halothane groups, respectively. The rats were regularly treated with the pre-determined treatment. We also scrutinized the serum proinflammatory cytokines including IL-10, IL-4 and IL-2; brain level IL-1β; hippocampal neuronal apoptosis concentration were estimated. The water maze test was performed in rats for the estimation of cognitive ability. During the water maze test, on the 1st day the sevoflurane group showed the latency; sevoflurane and sevoflurane + halothane group demonstrated the declined latency gradually as compared to the control group rats after the 3 days. The latency of the control, halothane, sevoflurane + halothane group rats showed the reduced latency and also showed the reduced crossing circle times. The hippocampal neuron apoptosis was significantly increased in halothane and sevoflurane + halothane group as compared to control group rats, respectively. Control group rats demonstrated the increased neuron apoptosis. The proinflammatory cytokines including IL-10 and IL-4 was significantly higher in sevoflurane, halothane and sevoflurane + halothane group rats after anesthesia and the whole brain IL-1β was significantly decrease in the sevoflurane, halothane and sevoflurane + halothane as compared to control group. Sevoflurane can inhibit the anesthesia effect of halothane on the immune and cognitive function of rats.     

Oral pioglitazone ameliorates fructose-induced peripheral insulin resistance and hippocampal gliosis but not restores inhibited hippocampal adult neurogenesis

Diet-associated insulin resistance (IR) is intimately correlated with the progression of metabolic syndrome and hippocampal dysfunction. Pioglitazone (PIO), a selective peroxisome proliferator-activated receptor gamma (PPARγ) agonist, has been applied to enhance insulin sensitivity. With limited permeability to blood-brain-barrier, it is unclear that whether oral PIO available to cure both the peripheral IR and the impairment in the hippocampus. We evaluated the levels of peripheral and hippocampal IR via the homeostatic model assessment of insulin resistance and hippocampal IRS-1/Akt phosphorylation, respectively, of Wistar Kyoto rats fed with a regular chew or high fructose diet (HFD) for 12 weeks. Gavage with PIO (30 mg/kg/day, 2 weeks) significantly reduced the peripheral IR and reversed the level of hippocampal PPARγ. Moreover, HFD-activated microglia and astrocyte were effectively relieved by PIO. The suppressed brain-derived neurotrophic factor, CaMKIIα, and postsynaptic density protein 95 in the hippocampus were effectively reversed by PIO. However, the hippocampal IR and inhibition of adult neurogenesis in dentate gyrus were not restored by PIO. Together, PIO oral application may reverse the HFD-induced peripheral IR and maintain the existed neuronal circuit by ameliorating glial activation and enhancing synaptic density through BDNF but failed to restore adult neurogenesis in the hippocampus.     

Co-activation of synaptic and extrasynaptic NMDA receptors by neuronal insults determines cell death in acute brain slice

Overactivation of NMDA receptors is linked to cell death during neuronal insults. However the precise role of synaptic and extrasynaptic NMDA receptors remains to be further determined. In this study, we used the acute brain slice to examine the contributions of synaptic and extrasynaptic NMDA receptors to neuronal death. By activation of synaptic NMDA receptors with bath application of 100 μM bicuculline in acute brain slices, we observed a significant up-regulation in activation of neuronal survival-related signaling (p-CREB, p-ERK1/2 and p-AKT), without an obvious increase of LDH release and neuronal death. Interestingly, activation of extrasynaptic NMDA receptors alone by high dose of glutamate (200 μM) following blockade of synaptic NMDA receptors with co-application of 20 μM MK801 and 100 μM bicuculline, we failed to observe inhibition of neuronal survival signaling and neuronal damage. In contrast, co-activation of synaptic and extrasynaptic NMDA receptors by applying 200 μM glutamate or oxygen–glucose deprivation (OGD) to acute brain slices for 30 min, we observed a significant inhibition of CREB, ERK1/2 and AKT activation, an increase of LDH release and neuronal condensation. Together, co-activation of synaptic and extrasynaptic NMDA receptors by neuronal insults contributes to cell death in acute brain slice.     

Ischemic hippocampal cell death induces glucose dysregulation by attenuating glucose-stimulated insulin secretion which is exacerbated by a high fat diet

AimsDiabetes increases the chances of stroke and the stroke itself is thought to induce hyperglycemia and diabetes. However, this latter contention remains uncorroborated. We investigated whether ischemic hippocampal neuronal cell death induces glucose dysregualtion by modulating insulin resistance, glucose-stimulated insulin secretion, and β-cell mass in Mongolian gerbils fed either a high fat or low fat diet.Main methodsGerbils were subjected to either an occlusion of the bilateral common carotid arteries for 8 mins to render them ischemic, or a sham operation. Ischemic gerbils were fed either an 11% fat diet (LFD) or a 40% fat diet (HFD) for 7, 14 or 28 days.Key findingsArtery occlusion resulted in a 70% or greater initial reduction in hippocampal CA1 neurons and only HFD decreased the percentage of CA1 neurons as the ischemic periods became longer. Oral glucose tolerance test (OGTT) results revealed that ischemia induced glucose intolerance, and longer ischemic periods and HFD exacerbated this glucose intolerance in ischemic gerbils. Insulin secretion during the OGTT was lower in ischemic gerbils than sham gerbils and the decrease was greatest in the 28 day-HFD among all the groups. Insulin resistance was elevated the most in 28 day-HFD ischemic gerbils. There was a progressive loss of pancreatic β-cell mass as the post-ischemic time period increased as consequence of HFD; the decrease being caused by increased apoptosis. This increase in apoptosis was partly associated with increased serum levels of IL-1β, TNF-α and non-esterified fatty acids.SignificanceHippoccampal neuronal cell death deteriorates glucose homeostasis initially through the modulation of insulin secretion and also causes a decrease in β-cell mass while HFD negatively impacts glucose regulation.     

Resveratrol Protects Against Neurotoxicity Induced by Kainic Acid

Increased oxidative stress has been implicated in the mechanisms of excitotoxicity in hippocampus induced by kainic acid (KA), an excitatory glutamate receptor agonist. Resveratrol, a polyphenolic antioxidant compound enriched in grape, is regarded as an important ingredient in red wine to offer cardiovascular and neural protective effects. This study was designed to investigate whether resveratrol treatment may ameliorate neuronal death after KA administration. Adult Sprague Dawley male rats were treated with KA (8 mg/kg) daily for 5 days and another group was treated similarly with KA plus resveratrol (30 mg/kg/day). Three hr after the last treatment protocol, animals were sacrificed, and brain sections were obtained for histochemical and immunohistochemical identification of neurons, astrocytes and microglial cells. After KA administration, significant neuronal death and activation of astrocytes and microglial cells were observed in the hippocampal CA1, CA3 and polymorphic layer (hilar) of the dentate gyrus (DG) (P < 0.001). The KA-induced hippocampal neuronal damage was significantly attenuated by treatment with resveratrol (P < 0.001). Resveratrol also suppressed KA-induced activation of astrocytes and microglial cells. Since increased oxidative stress is a key factor for KA-induced neurotoxicity, this study demonstrated the ability of resveratrol to act as free radical scavenger to protect against neuronal damage caused by excitotoxic insults.Special issue dedicated to Dr. Lawrence F. Eng.     

Dysideamine,a new sesquiterpene aminoquinone,protects hippocampal neuronal cells against iodoacetic acid-induced cell death

In the course of our search for neuroprotective agents, dysideamine (1), a new sesquiterpene aminoquinone, was isolated along with bolinaquinone (2) from Indonesian marine sponge of Dysidea sp. Compounds 1 and 2 showed neuroprotective effect against iodoacetic acid (IAA)-induced cell death at 10 μM concentration in mouse HT22 hippocampal neuronal cells. Dysideamine (1) inhibited production of reactive oxygen species (ROS) by IAA treatment, whereas it exhibited no effect on depletion of intracellular ATP of the IAA-treated HT22 cells. Moreover, 1 induced neurite outgrowth against mouse neuroblastma Neuro 2A cells with increase of acetylcholinesterase (AChE) activity, which is a marker of neuronal differentiation.     

Pyridoxine improves hippocampal cognitive function via increases of serotonin turnover and tyrosine hydroxylase,and its association with CB1 cannabinoid receptor-interacting protein and the CB1 cannabinoid receptor pathway

BackgroundIn the present study, we investigated the effects of pyridoxine on hippocampal functions and changes in protein profiles based on the proteomic approach.MethodsEight-week-old mice received intraperitoneal injections of physiological saline (vehicle) or 350 mg/kg pyridoxine twice a day for 21 days.ResultsPhosphoglycerate mutase 1 was up-regulated, while CB1 cannabinoid receptor-interacting protein 1 (CRIP1) was down-regulated, in the pyridoxine-treated group. Additionally, the serotonin and tyrosine hydroxylase was increased in the hippocampus of the pyridoxine-treated group than in that of the vehicle-treated group. Furthermore, discrimination indices based on the novel object recognition test were significantly higher in the pyridoxine-treated group than in the vehicle-treated group. Administration of CRIP1a siRNA significantly increases the discrimination index as well as cell proliferation and neuroblast differentiation in the dentate gyrus. In addition, the administration of rimonabant, a CB1 cannabinoid receptor antagonist, for 3 weeks significantly decreased the novel object recognition memory, the tyrosine hydroxylase level, the amount of cell proliferation, and neuroblast differentiation in the dentate gyrus. Treatment with pyridoxine significantly increased novel object recognition memory, but slightly ameliorated rimonabant-induced reduction in serotonin, the tyrosine hydroxylase level, the amount of cell proliferation, and neuroblast differentiation in the dentate gyrus.ConclusionThese results suggest that pyridoxine promotes hippocampal functions by increasing serotonin and tyrosine hydroylase immunoreactivity in the hippocampus. This positive effect may be associated with CRIP1a and CB1 cannabinoid receptor function.General significanceVitamin-B₆ enhances hippocampal functions and this is closely associated with CRIP1a and CB1 cannabinoid receptors.     

Neuroprotective effects of valproic acid following transient global ischemia in rats

AimsA growing number of studies demonstrate that valproic acid (VPA), an anti-convulsant and mood-stabilizing drug, is neuroprotective against various insults. This study investigated whether treatment of ischemic stroke with VPA ameliorated hippocampal cell death and cognitive deficits. Possible mechanisms of action were also investigated.Main methodsGlobal cerebral ischemia was induced to mimic ischemia/reperfusion (I/R) damage. The pyramidal cells within the CA1 field were stained with cresyl violet. Cognitive ability was measured 7 days after I/R using a Morris water maze. The anti-inflammatory effects of VPA on microglia were also investigated by immunohistochemistry. Pro-inflammatory cytokine production was determined using enzyme-linked immunosorbent assays (ELISA). Western blot analysis was performed to determine the levels of acetylated H3, H4 and heat shock protein 70 (HSP70) in extracts from the ischemic hippocampus.Key findingsVPA significantly increased the density of neurons that survived in the CA1 region of the hippocampus on the 7th day after transient global ischemia. VPA ameliorated severe deficiencies in spatial cognitive performance induced by transient global ischemia. Post-insult treatment with VPA also dramatically suppressed the activation of microglia but not astrocytes, reduced the number of microglia, and inhibited other inflammatory markers in the ischemic brain. VPA treatment resulted in a significant increase in levels of acetylated histones H3 and H4 as well as HSP70 in the hippocampus.SignificanceOur results indicated that VPA protected against hippocampal cell loss and cognitive deficits. Treatment with VPA following cerebral ischemia probably involves multiple mechanisms of action, including inhibition of ischemia-induced cerebral inflammation, inhibition of histone deacetylase (HDAC) and induction of HSP.     

Effect of high temperature on active oxygen species,senescence and photosynthetic properties in cucumber leaves

To gain a physiological understanding of the effects of high temperatures on cucumber (Cucumis sativus L.), we subjected seedlings to heat treatment at daytime temperatures of 28 °C, 32 °C, and 36 °C for 7 h a day for 30 days. The amount of active oxygen species, indicators of senescence, and photosynthetic properties in the second and third leaves were determined at the start of temperature treatment and on the 15th and 30th days of treatment. The amount of active oxygen species superoxide in leaves was greatest in the high temperature zones on the 15th day of treatment, and the amount of hydrogen peroxide was greatest in the high temperature zones on both the 15th and 30th days of treatment. The reduction in the amount of protein and the increase in the amount of malondialdehyde, both indicators of senescence, were greatest in the high temperature zones on both the 15th and 30th days of treatment, and the amount of chlorophyll was lowest in the 36 °C zone on the 15th day, and lower in the high temperature zones on the 30th day. It is clear from these results that a large amount of active oxygen species is generated and accumulated in the leaves at high temperatures, and senescence is significantly accelerated. The photosynthetic properties of stomatal conductance, sub-stomatal CO₂ concentration, and transpiration rate were at the same level on both the 15th and 30th days of treatment in all three temperature treatment zones. No significant difference was seen in the net photosynthesis rate between the 28 °C and 32 °C zones, was lower in the 36 °C zone than the 32 °C zone on the 15th day, and lowest in the 36 °C zone on the 30th day. CO₂ intake and water absorption are only mildly affected by high temperatures, and the reduction in net photosynthesis rate due to the 36 °C high temperature stress suggests that the large amount of active oxygen species induces inhibition of photosynthesis and damage to the mechanism of photosynthesis.     

Protein kinases paralleling late-phase LTP formation in dorsal hippocampus in the rat

Hippocampal long term potentiation (LTP), representing a cellular model for learning and memory formation, can be dissociated into at least two phases: a protein-synthesis-independent early phase, lasting about 4 h and a protein-synthesis-dependent late phase LTP lasting 6 h or longer, or even days. A large series of protein kinases have been shown to be involved and herein, a distinct set of protein kinases proposed to be involved in memory retrieval in previous work was tested in dorsal hippocampus of the rat following induction of late-phase LTP. A bipolar stimulation electrode was chronically implanted into the perforant path, while two monopolar recording electrodes were implanted into the dentate gyrus of the dorsal hippocampus. The recording electrode was measuring extracellular excitatory postsynaptic potentials, while the other one measured population spikes. Protein kinases were determined by immunoblotting and immunoflourescence on hippocampal areas showed the distribution pattern of protein kinases PKN1 and NEK7.Induction of LTP was proven, elevated levels for protein kinases PKN1, RPS6KB1, STK4, CDC42BPB, PRKG, TLK, BMX and decreased levels for NEK7, MAK14 and PLK1 were observed. A remarkable overlap of protein kinases observed in spatial memory processes with those proposed in LTP formation was demonstrated. The findings may be relevant for design of future studies on protein kinases and for the interpretation of previous work.     

Post-infarct treatment with [Pyr1]-apelin-13 reduces myocardial damage through reduction of oxidative injury and nitric oxide enhancement in the rat model of myocardial infarction

Apelin is a newly discovered peptide that has been recently shown to have cardioprotective effects in the animal model of myocardial infarction (MI) and ischemia/reperfusion (I/R) injuries. The aim of the present study was to investigate the long term cardioprotective effect of [Pyr1]-apelin-13 in the rat model of MI. Male Wistar rats (n = 22) were randomly divided into three groups: (1) sham operated group (2) control MI group and (3) MI treated with apelin (MI-AP group). MI animals were subjected to 30 min of left anterior descending coronary artery (LAD) ligation and 14 days of reperfusion. 24 h after LAD ligation, apelin (10 nmol/kg/day) was administered i.p. for 5 days. Blood sampling was performed at days 1, 3, 5 and 7 after MI for determination of serum changes of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), malondialdehyde (MDA) and nitric oxide (NO). Myocardial infarct size (IS) and hemodynamic function were also measured at the end of the study at day 14. We found out that post infarct treatment with apelin decreases infarct size, serum levels of LDH, CK-MB and MDA and increases heart rate and serum level of NO in the consecutive days, but there were no significant differences in blood pressure in the MI-AP group in comparison with MI. In conclusion, apelin has long term cardioprotective effects against myocardial infarction through attenuation of cardiac tissue injury and lipid peroxidation and enhancement of NO production.     

Maximizing mouse embryonic stem cell production in a stirred tank reactor by controlling dissolved oxygen concentration and continuous perfusion operation

One of the key challenges in stem cell bioprocessing is the large-scale cultivation of stem cells in order to meet the demanding meaningful cell numbers needed for biomedical applications, especially for clinical settings. Mouse embryonic stem cells [1], used as a model system herein, were cultivated on microcarriers in a fully controlled stirred tank reactor (STR) [2]. The impact of varying the concentration of dissolved oxygen (at 5%, 10%, 20% and 30% DO) and operating under a continuous perfusion mode on cell growth and pluripotency maintenance was investigated. In addition, in order to further optimize the feeding strategy of the STR operating under continuous perfusion toward maximal cell production, the influence of different medium residences times (12 h, 24 h, 32 h, 48 h and 96 h) was evaluated. Overall, the maximal cell concentration of 7.9–9.2 × 10⁶ cells/mL were attained after 11 days, with no passaging required, under a DO of 10–20% in the continuous perfused bioreactor with cell retention and medium residences times of 32–48 h. Importantly, mESC expanded under these conditions, retained the expression of pluripotency markers (Oct4, Nanog and Ssea-1), as well as their differentiation potential into cells of the three embryonic germ layers.The STR-based cultivation platform optimized herein represents a major contribution toward the development of large-volume production systems of differentiated cell derivatives for a wide range of biomedical applications.     

Quercetin ameliorates chronic unpredicted stress-mediated memory dysfunction in male Swiss albino mice by attenuating insulin resistance and elevating hippocampal GLUT4 levels independent of insulin receptor expression

Chronic stress is associated with impaired neuronal functioning, altered insulin signaling, and behavioral dysfunction. Quercetin has shown neuroprotective and antidiabetic effects, besides modulating cognition and insulin signaling. Therefore, in the present study, we explored whether or not quercetin ameliorates stress-mediated cognitive dysfunction and explored the underlying mechanism. Swiss albino male mice were subjected to an array of unpredicted stressors for 21 days, during which 30 mg/kg quercetin treatment was given orally. The effect of chronic unpredicted stress (CUS) and quercetin treatment on cognition were evaluated using novel object recognition (NOR) and Morris water maze (MWM) tests. Hippocampal neuronal integrity was observed by histopathological examination. Blood glucose, serum corticosterone, and insulin levels were measured by commercial kits and insulin resistance was evaluated in terms of HOMA-IR index. Hippocampal insulin signaling was determined by immunofluorescence staining. CUS induced significant cognitive dysfunction (NOR and MWM) and severely damaged hippocampal neurons, especially in the CA3 region. Quercetin treatment alleviated memory dysfunction and rescued neurons from CUS-mediated damage. Fasting blood glucose, serum corticosterone, and serum insulin were significantly elevated in stressed animals, besides, having significantly higher HOMA-IR index, suggesting the development of insulin resistance. Quercetin treatment alleviated insulin resistance and attenuated altered biochemical parameters. CUS markedly down-regulated insulin signaling in CA3 region and quercetin treatment improved neuronal GLUT4 expression, which seemed to be independent of insulin and insulin receptor levels. These results suggest that intact insulin functioning in the hippocampus is essential for cognitive functions and quercetin improves CUS-mediated cognitive dysfunction by modulating hippocampal insulin signaling.     

Enhanced beauvericin production with in situ adsorption in mycelial liquid culture of Fusarium redolens Dzf2

Fusarium redolens Dzf2, an endophytic fungal species, is a high producer of the antibiotic compound beauvericin (BEA). However, the BEA produced by the F. redolens Dzf2 fungus was retained mainly as an intracellular product. This study was to evaluate an integrated fermentation-in situ product recovery process for enhancement of BEA production in F. redolens Dzf2 myelical culture. A macroporous polystyrene resin (X-5) was selected as the sorbent and added to the mycelial culture flasks (enclosed in a nylon bag). With 2 g resin added to 40 ml medium in each flask in the early stationary growth phase (day 5), the volumetric BEA yield (on day 7) was increased from 194 to 265 mg l^?1, with 65% being adsorbed to the resin phase. With resin renewal plus glucose feeding (on day 7), the BEA production was increased even more dramatically to 400 mg l^?1 (on day 9), double of the yield in the batch control culture. The results show that in situ adsorption was an effective strategy for enhancing the BEA production and also facilitating its recovery in the mycelial liquid culture.     

Enfermedad cardiovascular tras infección por SARS-CoV-2 en pacientes ancianos. Resultados del seguimiento anual de una cohorte de supervivientes

IntroductionAlthough the effects of SARS-CoV-2 infection on the cardiovascular system is well known in the acute phase, the cardiovascular impact of the elderly population surviving COVID-19 respiratory infection after 1 year of follow-up has not been sufficiently studied.MethodsObservational registry of 240 elderly patients (75 years or older), consecutively admitted for COVID-19 respiratory infection and survivors of the same, between March 1 and April 30, 2020, at the Hospital General Universitario de Ciudad Real. The incidence of major cardiovascular events [MACE] (cardiovascular death [CD], acute coronary syndrome [ACS], cerebrovascular disease [CVD], venous thromboembolic disease [VTE] and heart failure [HF]) was prospectively analysed.ResultsThe mean age was 83.75 ± 5.75 years. After a mean follow-up of 352.2 ± 70.4 days, 13.8% of patients died and 9.6% had MACE, the most frequent being heart failure, with no differences in severity or overall course of acute illness. In the multivariate Cox regression model, the risk of developing MACE was higher in patients with chronic obstructive pulmonary disease and (HR 4.29; 95%CI 1.62-11.39; P = .003) and loop diuretic (HR 2.99; 95%CI 1.27-7.07; P = .01).ConclusionsIn elderly COVID-19 survivors, the incidence of MACE after one year of follow-up is high, the main manifestation being heart failure.     

Social ranking and plasma progesterone levels in goats

Progesterone is essential for maintaining pregnancy in goats, and embryonic losses may be a consequence of the reduction in circulating progesterone levels close to the time of implantation. Some evidence exists regarding social dominance affecting the plasma progesterone levels in several species—where dominant females conceive earlier. The objective of this research was to determine whether serum progesterone levels differ in goats of different social status. A behavioural study was conducted for 10 days in a herd of 57 does and an individual success index (SI) was calculated according to the result of aggressive interactions. Goats were classified as high (SI: 1–0.67), medium (SI: 0.66–0.34) and low-ranking (SI: 0.33–0.0). Ovulation was synchronized using two injections of prostaglandin 11 days apart, and the plasma progesterone levels determined daily for a period of 20 days. The area under the plasma progesterone curve during the entire study was greater in the high than in the medium and low-ranking does (96.2 ± 5.8, 79.5 ± 5.3 and 81.3 ± 5.3 ng/ml, respectively, P < 0.05). During days 11–17 following prostaglandin synchronization, the plasma progesterone levels were higher in the high-ranking (P < 0.05), compared to the low-ranking does. Plasma progesterone levels were significantly correlated with SI at days 14 and 15 (r = 0.26; P < 0.05). Results suggest a relationship between social ranking of goats and the plasma progesterone production from the corpus luteum and other possible sources.     

Diacylglycerol levels modulate the cellular distribution of the nicotinic acetylcholine receptor

Diacylglycerol (DAG), a second messenger involved in different cell signaling cascades, activates protein kinase C (PKC) and D (PKD), among other kinases. The present work analyzes the effects resulting from the alteration of DAG levels on neuronal and muscle nicotinic acetylcholine receptor (AChR) distribution. We employ CHO-K1/A5 cells, expressing adult muscle-type AChR in a stable manner, and hippocampal neurons, which endogenously express various subtypes of neuronal AChR. CHO-K1/A5 cells treated with dioctanoylglycerol (DOG) for different periods showed augmented AChR cell surface levels at short incubation times (30 min–4 h) whereas at longer times (18 h) the AChR was shifted to intracellular compartments. Similarly, in cultured hippocampal neurons surface AChR levels increased as a result of DOG incubation for 4 h. Inhibition of endogenous DAG catabolism produced changes in AChR distribution similar to those induced by DOG treatment. Specific enzyme inhibitors and Western blot assays revealed that DAGs exert their effect on AChR distribution through the modulation of the activity of classical PKC (cPKC), novel PKC (nPKC) and PKD activity.