Degree of COVID-19 severity and mortality in stroke: correlation of clinical and laboratory parameters

BACKGROUND

Stroke is one of the neurological manifestations of COVID-19, leading to a significant risk of morbidity and mortality. Clinical manifestations and laboratory parameters were investigated to determine mortality predictors in this case.

METHOD

The case control study was conducted at Dr. Sardjito General Hospital,Yogyakarta, Indonesia, with data collected between July 2020 and August 2021. All recorded clinical and laboratory data from acute stroke patients with confirmed COVID-19 were collected. Baseline characteristics, bivariate, and multivariate analyses were assessed to determine significant predictors for mortality.

RESULT

This study involved 72 subjects with COVID-19 and stroke. The majority experienced ischemic stroke, with hypertension as the most prevalent comorbidity. Notably, 45.8% of subjects (p < 0.05) loss of consciousness and 72.2% of exhibited motor deficits (p < 0.05). Severe degree of COVID-19 was observed in 52.8% of patients, with respiratory distress and death rates of 56.9% and 58.3%. Comparison of surviving and deceased groups highlighted significant differences in various clinical and laboratory characteristics differences. Hazard ratio (HR) analysis identified loss of consciousness (HR = 2.68; p = 0.01), motor deficit (HR = 2.34; p = 0.03), respiratory distress (HR = 81.51; p < 0.001), and monocyte count (HR:1.002; p = 0.04) as significant predictors of mortality.

CONCLUSION

Mortality in COVID-19 patients with stroke was significantly associated with loss of consciousness, motor deficit, respiratory distress, and raised monocyte count. The risk of mortality is heightened when multiple factors coexist.

Brain-derived neurotrophic factor interplay with oxidative stress: neuropathology approach in potential biomarker of Alzheimer's disease

The aging population poses a serious challenge concerning an increased prevalence of Alzheimer's disease (AD) and its impact on global burden, morbidity, and mortality. Oxidative stress, as a molecular hallmark that causes susceptibility in AD, interplays to other AD-related neuropathology cascades and decreases the expression of central and circulation brain-derived neurotrophic factor (BDNF), an essential neurotrophin that serves as nerve development and survival, and synaptic plasticity in AD. By its significant correlation with the molecular and clinical progression of AD, BDNF can potentially be used as an objectively accurate biomarker for AD diagnosis and progressivity follow-up in future clinical practice. This comprehensive review highlights the oxidative stress interplay with BDNF in AD neuropathology and its potential use as an AD biomarker.

Folic Acid Treatment for Patients with Vascular Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

As the life expectancy of elderly people has drastically increased, the incidence of cardiovascular and cerebrovascular diseases in this population has proportionally grown. Vascular cognitive impairment (VCI) refers to all forms of cognitive disorder associated with cerebrovascular disease. Homocysteine has recently been recognized as a contributor to the pathomechanisms involved in cognitive impairment. B vitamins, such as folic acid, are known to be effective in lowering homocysteine levels.

AIM OF THE STUDY

To evaluate the efficacy of folic acid in patients with VCI.

METHODS

We conducted a systematic review and meta-analysis of research on folic acid treatments for VCI. Only randomized controlled trials studies that compared the efficacy of folic acid to placebo or other interventions were considered, irrespective of publication status, year of publication, and languages. Two independent reviewers searched the Medline via Ovid, EMBASE and Cochrane Central Register of Controlled Trials (Central) journal databases up to July 2021 and independently appraised the included studies. We used mean difference outcome with 95% confidence intervals (CI) to calculate the change of Mini-Mental State Examination (MMSE), cognitive function domain, and concentration of homocysteine.

RESULTS

We found three studies comparing folic acid with placebo and one study comparing folic acid with other interventions. There is only slight evidence that the MMSE score in patients who received Folic Acid increased 0.3 point higher compared to the placebo group after 24 months (95% CI:-0.12-0.37; p=0.31). There is very strong evidence that the concentration of Homocysteine in the Folic Acid group became 6.16 μmol/L lower compared to the placebo group after 6 months (95% CI:2.32-8.21 lower; p<0.001).

CONCLUSIONS

Our review shows the effectiveness of folic acid in lowering plasma homocysteine concentration after 6 months period compared to placebo. However, this effect is not accompanied by improvement in cognitive function.

Adenosine 2A receptor inhibition protects phrenic motor neurons from cell death induced by protein synthesis inhibition

Respiratory motor neuron survival is critical for maintenance of adequate ventilation and airway clearance, preventing dependence to mechanical ventilation and respiratory tract infections. Phrenic motor neurons are highly vulnerable in rodent models of motor neuron disease versus accessory inspiratory motor pools (e.g. intercostals, scalenus). Thus, strategies that promote phrenic motor neuron survival when faced with disease and/or toxic insults are needed to help preserve breathing ability, airway defense and ventilator independence. Adenosine 2A receptors (A2A) are emerging as a potential target to promote neuroprotection, although their activation can have both beneficial and pathogenic effects. Since the role of A2A receptors in the phrenic motor neuron survival/death is not known, we tested the hypothesis that A2A receptor antagonism promotes phrenic motor neuron survival and preserves diaphragm function when faced with toxic, neurodegenerative insults that lead to phrenic motor neuron death. We utilized a novel neurotoxic model of respiratory motor neuron death recently developed in our laboratory: intrapleural injections of cholera toxin B subunit (CtB) conjugated to the ribosomal toxin, saporin (CtB-Saporin). We demonstrate that intrapleural CtB-Saporin causes: 1) profound phrenic motor neuron death (~5% survival); 2) ~7-fold increase in phrenic motor neuron A2A receptor expression prior to cell death; and 3) diaphragm muscle paralysis (inactive in most rats; ~7% residual diaphragm EMG amplitude during room air breathing). The A2A receptor antagonist istradefylline given after CtB-Saporin: 1) reduced phrenic motor neuron death (~20% survival) and 2) preserved diaphragm EMG activity (~46%). Thus, A2A receptors contribute to neurotoxic phrenic motor neuron death, an effect mitigated by A2A receptor antagonism.

Compensatory plasticity in diaphragm and intercostal muscle utilization in a rat model of ALS

In SOD1^G93A transgenic rat model of ALS, breathing capacity is preserved until late in disease progression despite profound respiratory motor neuron (MN) cell death. To explore mechanisms preserving breathing capacity, we assessed inspiratory EMG activity in diaphragm and external intercostal T2 (EIC2) and T5 (EIC5) muscles in anesthetized SOD1^G93A rats at disease end-stage (20% decrease in body mass). We hypothesized that despite significant phrenic motor neuron loss and decreased phrenic nerve activity, diaphragm electrical activity and trans-diaphragmatic pressure (Pdi) are maintained to sustain ventilation. We alternatively hypothesized that EIC activity is enhanced, compensating for impaired diaphragm function. Diaphragm, EIC2 and EIC5 muscle EMGs and Pdi were measured in urethane-anesthetized, spontaneously breathing female SOD1^G93A rats versus wild-type littermates during normoxia (arterial PO₂ ~90mmHg, PCO₂ ~45mmHg), maximal chemoreceptor stimulation (MCS: 10.5% O₂/7% CO₂), spontaneous augmented breaths and sustained tracheal occlusion. Phrenic MNs were counted in C3-5; T2 and T5 ventrolateral MNs were counted. In end-stage SOD1^G93A rats, 29% of phrenic MNs survived (vs. wild-type), yet integrated diaphragm EMG amplitude was normal. Nevertheless, maximal Pdi decreased ~30% vs. wild type (p<0.01) and increased esophageal to gastric pressure ratio (p<0.05), consistent with persistent diaphragm weakness. Despite major T2 and T5 MN death, integrated EIC2 (100% greater than wild type) and EIC5 (300%) EMG amplitudes were increased in mutant rats during normoxia (p<0.01), possibly compensating for decreased Pdi. Thus, despite significant phrenic MN loss, diaphragm EMG activity is maintained; in contrast, Pdi was not, suggesting diaphragm dysfunction. Presumably, increased EIC EMG activity compensated for persistent diaphragm weakness. These adjustments contribute to remarkable preservation of breathing ability despite major respiratory motor neuron death and diaphragm dysfunction.

Repetitive acute intermittent hypoxia increases growth/neurotrophic factor expression in non-respiratory motor neurons

Repetitive acute intermittent hypoxia (rAIH) increases growth/trophic factor expression in respiratory motor neurons, thereby eliciting spinal respiratory motor plasticity and/or neuroprotection. Here we demonstrate that rAIH effects are not unique to respiratory motor neurons, but are also expressed in non-respiratory, spinal alpha motor neurons and upper motor neurons of the motor cortex. In specific, we used immunohistochemistry and immunofluorescence to assess growth/trophic factor protein expression in spinal sections from rats exposed to AIH three times per week for 10weeks (3×wAIH). 3×wAIH increased brain-derived neurotrophic factor (BDNF), its high-affinity receptor, tropomyosin receptor kinase B (TrkB), and phosphorylated TrkB (pTrkB) immunoreactivity in putative alpha motor neurons of spinal cervical 7 (C7) and lumbar 3 (L3) segments, as well as in upper motor neurons of the primary motor cortex (M1). 3×wAIH also increased immunoreactivity of vascular endothelial growth factor A (VEGFA), the high-affinity VEGFA receptor (VEGFR-2) and an important VEGF gene regulator, hypoxia-inducible factor-1α (HIF-1α). Thus, rAIH effects on growth/trophic factors are characteristic of non-respiratory as well as respiratory motor neurons. rAIH may be a useful tool in the treatment of disorders causing paralysis, such as spinal injury and motor neuron disease, as a pretreatment to enhance motor neuron survival during disease, or as preconditioning for cell-transplant therapies.

Optimization of a Clinically Relevant Model of White Matter Stroke in Mice: Histological and Functional Evidences

BACKGROUND AND PURPOSE

White matter (WM) injury during stroke increases the risk of disability and gloomy prognosis of post-stroke rehabilitation. However, modeling of WM loss in rodents has proven to be challenging.

METHODS

We report improved WM injury models in male C57BL/6 mice. Mice were given either endothelin-1 (ET-1) or L-N5-(1-iminoethyl)ornitine (L-NIO) into the periventricular white matter (PVWM), in the corpus callosum (CC), or in the posterior limb of internal capsule (PLIC). Anatomical and functional outcomes were quantified on day 7 post injection.

RESULTS

Injection of ET-1 or L-NIO caused a small focal lesion in the injection site in the PVWM. No significant motor function deficits were observed in the PVWM lesion model. We next targeted the PLIC by using single or double injections of L-NIO and found that this strategy induced small focal infarction. Interestingly, injection of L-NIO in the PLIC also resulted in gliosis, and significant motor function deficits.

CONCLUSIONS

By employing different agents, doses, and locations, this study shows the feasibility of inducing brain WM injury accompanied with functional deficits in mice. Selective targeting of the injury location, behavioral testing, and the agents chosen to induce WM injury are all keys to successfully develop a mouse model and subsequent testing of therapeutic interventions against WM injury.

Acute intermittent hypoxia induced phrenic long-term facilitation despite increased SOD1 expression in a rat model of ALS

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease characterized by motor neuron death. Since most ALS patients succumb to ventilatory failure from loss of respiratory motor neurons, any effective ALS treatment must preserve and/or restore breathing capacity. In rats over-expressing mutated super-oxide dismutase-1 (SOD1(G93A)), the capacity to increase phrenic motor output is decreased at disease end-stage, suggesting imminent ventilatory failure. Acute intermittent hypoxia (AIH) induces phrenic long-term facilitation (pLTF), a form of spinal respiratory motor plasticity with potential to restore phrenic motor output in clinical disorders that compromise breathing. Since pLTF requires NADPH oxidase activity and reactive oxygen species (ROS) formation, it is blocked by NADPH oxidase inhibition and SOD mimetics in normal rats. Thus, we hypothesized that SOD1(G93A) (mutant; MT) rats do not express AIH-induced pLTF due to over-expression of active mutant superoxide dismutase-1. AIH-induced pLTF and hypoglossal (XII) LTF were assessed in young, pre-symptomatic and end-stage anesthetized MT rats and age-matched wild-type littermates. Contrary to predictions, pLTF and XII LTF were observed in MT rats at all ages; at end-stage, pLTF was actually enhanced. SOD1 levels were elevated in young and pre-symptomatic MT rats, yet superoxide accumulation in putative phrenic motor neurons (assessed with dihydroethidium) was unchanged; however, superoxide accumulation significantly decreased at end-stage. Thus, compensatory mechanisms appear to maintain ROS homoeostasis until late in disease progression, preserving AIH-induced respiratory plasticity. Following intrathecal injections of an NADPH oxidase inhibitor (apocynin; 600 μM; 12 μL), pLTF was abolished in pre-symptomatic, but not end-stage MT rats, demonstrating that pLTF is NADPH oxidase dependent in pre-symptomatic, but NADPH oxidase independent in end-stage MT rats. Mechanisms preserving/enhancing the capacity for pLTF in MT rats are not known.

Considerations for the Optimization of Induced White Matter Injury Preclinical Models

White matter (WM) injury in relation to acute neurologic conditions, especially stroke, has remained obscure until recently. Current advances in imaging technologies in the field of stroke have confirmed that WM injury plays an important role in the prognosis of stroke and suggest that WM protection is essential for functional recovery and post-stroke rehabilitation. However, due to the lack of a reproducible animal model of WM injury, the pathophysiology and mechanisms of this injury are not well studied. Moreover, producing selective WM injury in animals, especially in rodents, has proven to be challenging. Problems associated with inducing selective WM ischemic injury in the rodent derive from differences in the architecture of the brain, most particularly, the ratio of WM to gray matter in rodents compared to humans, the agents used to induce the injury, and the location of the injury. Aging, gender differences, and comorbidities further add to this complexity. This review provides a brief account of the techniques commonly used to induce general WM injury in animal models (stroke and non-stroke related) and highlights relevance, optimization issues, and translational potentials associated with this particular form of injury.

Treatment of stroke related refractory brain edema using mixed vasopressin antagonism: a case report and review of the literature

Background

Elevated intracranial pressure from cerebral edema is the major cause of early mortality in acute stroke. Current treatment strategies to limit cerebral edema are not particularly effective. Some novel anti-edema measures have shown promising early findings in experimental stroke models. Vasopressin antagonism in stroke is one such target which has shown some encouraging preliminary results. The aim of this report is to highlight the potential use of vasopressin antagonism to limit cerebral edema in patients after acute stroke.

Case presentation

A 57-year-old Caucasian man with new onset diplopia was diagnosed with vertebral artery aneurysm extending into the basilar circulation. He underwent successful elective vertebral artery angioplasty and coiling of the aneurysm. In the immediate post-operative period there was a decline in his neurological status and brain imaging revealed new midbrain and thalamic hemorrhage with surrounding significant brain edema. Treatment with conventional anti-edema therapy was initiated with no significant clinical response after which conivaptan; a mixed vasopressin antagonist was started. Clinical and radiological evaluation following drug administration showed rapid clinical improvement without identification of significant adverse effects.

Conclusions

The authors have successfully demonstrated the safety and efficacy of using mixed vasopressin antagonist in treatment of stroke related brain edema, thereby showing its promise as an alternative anti-edema agent. Preliminary findings from this study suggest mixed vasopressin antagonism may have significant utility in the management of cerebral edema arising from cerebrovascular accident. Larger prospective studies are warranted to explore the role of conivaptan in the treatment of brain edema and neuroprotection.

Neither serotonin nor adenosine-dependent mechanisms preserve ventilatory capacity in ALS rats

In rats over-expressing SOD1G93A, ventilation is preserved despite significant loss of respiratory motor neurons. Thus, unknown forms of compensatory respiratory plasticity may offset respiratory motor neuron cell death. Although mechanisms of such compensation are unknown, other models of respiratory motor plasticity may provide a conceptual guide. Multiple cellular mechanisms give rise to phrenic motor facilitation; one mechanism requires spinal serotonin receptor and NADPH oxidase activity whereas another requires spinal adenosine receptor activation. Here, we studied whether these mechanisms contribute to compensatory respiratory plasticity in SOD1G93A rats. Using plethysmography, we assessed ventilation in end-stage SOD1G93A rats after: (1) serotonin depletion with parachlorophenylalanine (PCPA), (2) serotonin (methysergide) and A2A (MSX-3) receptor inhibition, (3) NADPH oxidase inhibition (apocynin), and (4) combined treatments. The ability to increase ventilation was not decreased by individual or combined treatments; thus, these mechanisms do not maintain breathing capacity at end-stage motor neuron disease. Possible mechanisms giving rise to enhanced breathing capacity with combined treatment in end-stage SOD1G93A rats are discussed.

Ventilatory control in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to "fight back" via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients.

Intermittent hypoxia and stem cell implants preserve breathing capacity in a rodent model of amyotrophic lateral sclerosis

RATIONALE

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease causing paralysis and death from respiratory failure. Strategies to preserve and/or restore respiratory function are critical for successful treatment. Although breathing capacity is maintained until late in disease progression in rodent models of familial ALS (SOD1(G93A) rats and mice), reduced numbers of phrenic motor neurons and decreased phrenic nerve activity are observed. Decreased phrenic motor output suggests imminent respiratory failure.

OBJECTIVES

To preserve or restore phrenic nerve activity in SOD1(G93A) rats at disease end stage.

METHODS

SOD1(G93A) rats were injected with human neural progenitor cells (hNPCs) bracketing the phrenic motor nucleus before disease onset, or exposed to acute intermittent hypoxia (AIH) at disease end stage.

MEASUREMENTS AND MAIN RESULTS

The capacity to generate phrenic motor output in anesthetized rats at disease end stage was: (1) transiently restored by a single presentation of AIH; and (2) preserved ipsilateral to hNPC transplants made before disease onset. hNPC transplants improved ipsilateral phrenic motor neuron survival.

CONCLUSIONS

AIH-induced respiratory plasticity and stem cell therapy have complementary translational potential to treat breathing deficits in patients with ALS.

Repetitive acute intermittent hypoxia increases expression of proteins associated with plasticity in the phrenic motor nucleus

Acute intermittent hypoxia (AIH) initiates plasticity in respiratory motor control, including phrenic long term facilitation (pLTF). Since pLTF is enhanced by preconditioning with repetitive exposure to AIH (rAIH), we hypothesized that a rAIH protocol consisting of 3 AIH exposures per week for 10 weeks (3×wAIH; AIH: 10, 5-min episodes of 10.5% O(2); 5-min normoxic intervals) would enhance expression of molecules that play key roles in pLTF within the phrenic motor nucleus. Immunohistochemical analyses revealed that 3×wAIH for 10 weeks increased serotonin terminal density in the C4 phrenic motor nucleus and serotonin 2A (5-HT(2A)) receptor expression in presumptive phrenic motor neurons. Immunoreactive brain derived neurotrophic factor (BDNF) and its high affinity receptor (TrkB) also increased following 3×wAIH. 3×wAIH also increased expression of another hypoxia-sensitive growth factor known to elicit phrenic motor facilitation, vascular endothelial growth factor (VEGF), and its receptor (VEGFR-2). Kinases "downstream" from TrkB and VEGFR-2 were up-regulated in or near presumptive phrenic motor neurons, including phosphorylated extracellular-signal regulated kinase (p-ERK) and protein kinase B (p-AKT). Thus, 3×wAIH up-regulates neurochemicals known to be associated with phrenic motor plasticity. Since 3×wAIH upregulates pro-plasticity molecules without evidence for CNS pathology, it may be a useful therapeutic tool in treating disorders that cause respiratory insufficiency, such as spinal injury or motor neuron disease.

Spinal plasticity following intermittent hypoxia: implications for spinal injury

Plasticity is a fundamental property of the neural system controlling breathing. One frequently studied model of respiratory plasticity is long-term facilitation of phrenic motor output (pLTF) following acute intermittent hypoxia (AIH). pLTF arises from spinal plasticity, increasing respiratory motor output through a mechanism that requires new synthesis of brain-derived neurotrophic factor, activation of its high-affinity receptor, tropomyosin-related kinase B, and extracellular-related kinase mitogen-activated protein kinase signaling in or near phrenic motor neurons. Because intermittent hypoxia induces spinal plasticity, we are exploring the potential to harness repetitive AIH as a means of inducing functional recovery in conditions causing respiratory insufficiency, such as cervical spinal injury. Because repetitive AIH induces phenotypic plasticity in respiratory motor neurons, it may restore respiratory motor function in patients with incomplete spinal injury.

NADPH oxidase activity is necessary for acute intermittent hypoxia-induced phrenic long-term facilitation

Phrenic long-term facilitation (pLTF) following acute intermittent hypoxia (AIH) is a form of spinal, serotonin-dependent synaptic plasticity that requires reactive oxygen species (ROS) formation. We tested the hypothesis that spinal NADPH oxidase activity is a necessary source of ROS for pLTF. Sixty minutes post-AIH (three 5-min episodes of 11% O(2), 5 min intervals), integrated phrenic and hypoglossal (XII) nerve burst amplitudes were increased from baseline, indicative of phrenic and XII LTF. Intrathecal injections (approximately C(4)) of apocynin or diphenyleneiodonium chloride (DPI), two structurally and functionally distinct inhibitors of the NADPH oxidase complex, attenuated phrenic, but not XII, LTF. Immunoblots from soluble (cytosolic) and particulate (membrane) fractions of ventral C(4) spinal segments revealed predominantly membrane localization of the NADPH oxidase catalytic subunit, gp91(phox), whereas membrane and cytosolic expression were both observed for the regulatory subunits, p47(phox) and RAC1. Immunohistochemical analysis of fixed tissues revealed these same subunits in presumptive phrenic motoneurons of the C(4) ventral horn, but not in neighbouring astrocytes or microglia. Collectively, these data demonstrate that NADPH oxidase subunits localized within presumptive phrenic motoneurons are a major source of ROS necessary for AIH-induced pLTF. Thus, NADPH oxidase activity is a key regulator of spinal synaptic plasticity, and may be a useful pharmaceutical target in developing therapeutic strategies for respiratory insufficiency in patients with, for example, cervical spinal injury.

Substance P is a promoter of adult neural progenitor cell proliferation under normal and ischemic conditions

OBJECT

Neurogenesis continues throughout the life of mammals in the subventricular zone (SVZ) of the lateral ventricles and the dentate gyrus (DG) of the hippocampus. The authors tested the potential of the neuropeptide substance P (SP) acting via the neurokinin-1 receptor (NK1R) in promoting the proliferation of adult rat neural progenitor cells (NPCs).

METHODS

Focal ischemia was induced in spontaneously hypertensive rats by transient middle cerebral artery occlusion. Substance P and the NK1R antagonist L-703,606 were infused into the lateral ventricles of rats by using Alzet osmotic minipumps. Progenitor cell proliferation was evaluated with immunostaining for bromodeoxyuridine (BrdU) and immature neural marker doublecortin (DCX). Neurospheres were cultured from the SVZ of adult rats.

RESULTS

Under in vitro conditions, SP (0.01-10 micromol/L) increased the proliferation of cultured NPCs, with a peak increase of 52 +/- 7% at 0.1 micromol/L. Substance P (0.1 micromol/L) continuously increased NPC proliferation from 6 hours to 5 days, which was prevented by L-703,606 (by 69-98%). The cultured NPCs expressed both SP and NK1R proteins, indicating that these effects are receptor specific. Continuous infusion of SP (1 micromol/L) into the lateral ventricles for 5 days significantly increased the number of proliferating NPCs (cells positive for both BrdU and DCX) in both the SVZ (by 173 +/- 24%, p < 0.05) and DG (by 82 +/- 12%, p < 0.05) in adult rats; however, infusion of L-703,606 (10 micromol/L) significantly prevented the postischemic induction of NPC proliferation in both the SVZ (by 84 +/- 6%, p < 0.05) and DG (by 63 +/- 7%, p < 0.05).

CONCLUSIONS

Data in these studies indicated that SP plays a role in normal and ischemia-induced neurogenesis in the adult brain and thus could help central nervous system plasticity following injury.

Thiazolidinedione Class of Peroxisome Proliferator-Activated Receptor γ Agonists Prevents Neuronal Damage, Motor Dysfunction, Myelin Loss, Neuropathic Pain, and Inflammation after Spinal Cord Injury in Adult Rats

Thiazolidinediones (TZDs) are potent synthetic agonists of the ligand-activated transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma). TZDs were shown to induce neuroprotection after cerebral ischemia by blocking inflammation. As spinal cord injury (SCI) induces massive inflammation that precipitates secondary neuronal death, we currently analyzed the therapeutic efficacy of TZDs pioglitazone and rosiglitazone after SCI in adult rats. Both pioglitazone and rosiglitazone (1.5 mg/kg i.p.; four doses at 5 min and 12, 24, and 48 h) significantly decreased the lesion size (by 57 to 68%, p < 0.05), motor neuron loss (by 3- to 10-fold, p < 0.05), myelin loss (by 66 to 75%, p < 0.05), astrogliosis (by 46 to 61%, p < 0.05), and microglial activation (by 59 to 78%, p < 0.05) after SCI. TZDs significantly enhanced the motor function recovery (at 7 days after SCI, the motor scores were 37 to 45% higher in the TZD groups over the vehicle group; p < 0.05), but the treatment was effective only when the first injection was given by 2 h after SCI. At 28 days after SCI, chronic thermal hyperalgesia was decreased significantly (by 31 to 39%; p < 0.05) in the pioglitazone group compared with the vehicle group. At 6 h after SCI, the pioglitazone group showed significantly less induction of inflammatory genes [interleukin (IL)-6 by 83%, IL-1beta by 87%, monocyte chemoattractant protein-1 by 75%, intracellular adhesion molecule-1 by 84%, and early growth response-1 by 67%] compared with the vehicle group (p < 0.05 in all cases). Pioglitazone also significantly enhanced the post-SCI induction of neuroprotective heat shock proteins and antioxidant enzymes. Pretreatment with a PPARgamma antagonist, 2-chloro-5-nitro-N-phenyl-benzamide (GW9662), prevented the neuroprotection induced by pioglitazone.

Age-related changes in growth hormone-immunoreactive cells in the anterior pituitary gland of Jcl: Wistar-TgN (ARGHGEN) 1Nts rats (Mini rats)

Rats of the Jcl: Wistar-TgN (ARGHGEN) 1Nts strain (Mini rats) are transgenic animals carrying an antisense RNA transgene for rat growth hormone (GH); they show poor somatic growth and a low blood GH level compared to age-matched wild-type Wistar (non-Mini) rats. The purpose of the present study was to investigate age-related changes in growth hormone-immunoreactive (GH-IR) cells in the anterior pituitary gland (AP) of Mini rats at four, six, and eight weeks of age. The body weight and size of the GH-IR cells of Mini rats was significantly lower than that of non-Mini rats at six and eight weeks of age; however, this difference was not observed at four weeks of age. The AP volume and the number of GH-IR cells in Mini rats were significantly smaller than those of the age-matched non-Mini rats at the three ages. These results suggest that the abnormal development of GH-IR cells in the AP induced by the GH antisense RNA transgene is responsible for the poor somatic growth and the low blood GH levels in Mini rats.

Peroxisome proliferator-activated receptor-γ agonists induce neuroprotection following transient focal ischemia in normotensive, normoglycemic as well as hypertensive and type-2 diabetic rodents

Thiazolidinediones (TZDs) are synthetic agonists of the ligand-activated transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma). TZDs are known to curtail inflammation associated with peripheral organ ischemia. As inflammation precipitates the neuronal death after stroke, we tested the efficacy of TZDs in preventing brain damage following transient middle cerebral artery occlusion (MCAO) in adult rodents. As hypertension and diabetes complicate the stroke outcome, we also evaluated the efficacy of TZDs in hypertensive rats and type-2 diabetic mice subjected to transient MCAO. Pre-treatment as well as post-treatment with TZDs rosiglitazone and pioglitazone significantly decreased the infarct volume and neurological deficits in normotensive, normoglycemic, hypertensive and hyperglycemic rodents. Rosiglitazone neuroprotection was not enhanced by retinoic acid x receptor agonist 9-cis-retinoic acid, but was prevented by PPARgamma antagonist GW9662. Rosiglitazone significantly decreased the post-ischemic intercellular adhesion molecule-1 expression and extravasation of macrophages and neutrophils into brain. Rosiglitazone treatment curtailed the post-ischemic expression of the pro-inflammatory genes interleukin-1beta, interleukin-6, macrophage inflammatory protein-1alpha, monocyte chemoattractant protein-1, cyclooxygenase-2, inducible nitric oxide synthase, early growth response-1, CCAAT/enhancer binding protein-beta and nuclear factor-kappa B, and increased the expression of the anti-oxidant enzymes catalase and copper/zinc-superoxide dismutase. Rosiglitazone also increased the expression of the anti-inflammatory gene suppressor of cytokine signaling-3 and prevented the phosphorylation of the transcription factor signal transducer and activator of transcription-3 after focal ischemia. Thus, PPARgamma activation with TZDs might be a potent therapeutic option for preventing inflammation and neuronal damage after stroke with promise in diabetic and hypertensive subjects.

B1 and TRPV-1 receptor genes and their relationship to hyperalgesia following spinal cord injury

STUDY DESIGN

Laboratory investigation of pain behavior following spinal cord injury.

OBJECTIVE

To explore changes in the spinal cord expression of nociceptive genes following spinal cord injury (SCI) as they relate to the manifestation of pain behavior in rats.

SUMMARY OF BACKGROUND DATA

Neuropathic pain following SCI is common, disabling, and largely untreatable. In peripheral nerve injury models, bradykinin B1 and vanilloid 1 (TRPV-1) receptor activity is associated with neuropathic pain behavior. We sought to examine the role of these gene products in SCI-mediated pain.

METHODS

Rats were subjected to SCI using the MASCIS impactor. Animals were tested preinjury and at regular intervals postinjury for the appearance of thermal hyperalgesia using a hind limb withdrawal latency test. The expression of B1 and TRPV-1 genes was assessed using real-time polymerase chain reaction. Immunohistochemistry was used to localize the B1 and TRPV-1 receptors within the spinal cord.

RESULTS

Greater than twofold increases in the expression of the B1 and TRPV-1 genes were detected in the injured region of the spinal cord in animals exhibiting hyperalgesia compared with animals with SCI that did not display hyperalgesia. Immunohistochemical staining revealed that both receptor types were largely localized to the dorsal horn. Staining for TRPV-1 receptors decreased while that for B1 receptors increased in all of the injured animals when compared with sham-operated controls.

CONCLUSION

B1 and TRPV-1 receptor genes are overexpressed in the injured spinal cord of animals manifesting thermal hyperalgesia following SCI compared with similarly injured animals without hyperalgesia. This finding is consistent with past work regarding the role of these receptors in nociception and indicates that ongoing modifiable processes are occurring in the spinal cord that lead to clinical pain syndromes.

JAK2 and STAT3 activation contributes to neuronal damage following transient focal cerebral ischemia

Increased levels of interleukin-6 (IL-6) play a role in post-ischemic cerebral inflammation. IL-6 binding to its receptors induces phosphorylation of the receptor associated janus kinases (JAKs), and the down-stream signal transducer and activator of transcription (STAT) family of transcription factors, which amplify the IL-6 signal transduction. We evaluated the functional significance of JAK2 and STAT3 activation in focal ischemia-induced neuronal damage. Transient middle cerebral artery occlusion in adult rats led to increased JAK2 and STAT3 phosphorylation in the ipsilateral cortex and striatum after 6-72 h of reperfusion. Fluorescent immunohistochemistry with cell specific markers (NeuN for neurons, glial fibrillary acidic protein for reactive astrocytes and ED1/OX42 for activated macrophages/microglia) showed that both pJAK2 and pSTAT3 staining is predominantly localized in the macrophages/microglia in the post-ischemic brain. Intracerebroventricular infusion of rats with AG490 (a JAK2 phosphorylation inhibitor) prevented the post-ischemic JAK2 and STAT3 phosphorylation and significantly decreased the infarct volume, number of apoptotic cells and neurological deficits, compared to vehicle control. Furthermore, intracerebral injection of siRNA specific for STAT3 led to curtailed STAT3 mRNA expression and phosphorylation, decreased infarct volume, fewer apoptotic cells and improved neurological function following transient middle cerebral artery occlusion. These studies show that JAK2-STAT3 activation plays a role in post-ischemic brain damage.

Serotonin-induced in vitro long-term facilitation exhibits differential pattern sensitivity in cervical and thoracic inspiratory motor output

Intermittent hypoxia induces 5-HT-dependent, pattern-sensitive long-term facilitation (LTF) of spinal respiratory motor output. We used a split-bath in vitro neonatal rat brainstem-spinal cord preparation to test whether: 1) intermittent spinal 5-HT exposure (without hypoxia) is sufficient to induce LTF in phrenic and intercostal inspiratory motor outputs; 2) LTF magnitude is greater in intercostal versus phrenic activity; and 3) phrenic and intercostal motor output exhibits differential pattern sensitivity to 5-HT application. With a barrier at spinal segment C1, 5-HT (5 muM) was applied episodically (3 min 5-HT, 5 min wash, x3) to the spinal cord (C2-L1) while recording inspiratory bursts in cervical (C4 or C5) and thoracic (T5 or T6) ventral roots. Episodic 5-HT application increased cervical and thoracic burst amplitudes to 136+/-22% and 150+/-22% of baseline, respectively, at 120 min post-drug (P<0.01). Continuous 5-HT application (5 muM, 9 min) had no effect on cervical burst amplitude at 120 min post-drug, but increased thoracic burst amplitude to 142+/-11% of baseline at 120 min post-drug (P<0.001). Methysergide pretreatment abolished both cervical and thoracic 5-HT-induced LTF. Quantitative reverse transcriptase-polymerase chain reaction and immunocytochemistry revealed that 5-HT(2A) and 5-HT(7) receptor subtypes (receptors known to influence LTF expression in adult rats) are expressed in ventral cervical and thoracic spinal cord with no differences in expression levels due to spinal segment or age. Thus, 5-HT is sufficient to induce spinal LTF in neonatal rats and differences in pattern sensitivity suggest heterogeneity in underlying mechanisms.

Changes of parvalbumin immunoreactive neurons and GFAP immunoreactive astrocytes in the rat lateral geniculate nucleus following monocular enucleation

The expression of calcium binding proteins (CaBPs) has been linked to protection of neurons. The present study investigated the effects of monocular enucleation on the distribution of parvalbumin immunoreactive (PV-IR) neurons and glial fibrillary acidic protein immunoreactive (GFAP-IR) astrocytes in both the dorsal (dLGN) and ventral (vLGN) regions of the lateral geniculate nucleus (LGN). Our results demonstrated an increase in PV-IR neuronal density on the contralateral vLGN at 1-week post-enucleation (PE), which was maintained without significant change for 12 weeks. By contrast, PV-IR neurons in dLGN decreased significantly at all time point examined. The number of GFAP-IR astrocytes showed an initial increase from 1 to 4 weeks PE and then gradually decreased until 48 weeks in both regions of the LGN with contralateral side predominance. The present results suggest that monocular enucleation results in variable expression of PV-IR neurons and GFAP-IR astrocytes in the LGN complex, which may play an important role in neuronal degeneration and neuroplasticity of the rat visual system.

Application of the physical disector to the central nervous system: estimation of the total number of neurons in subdivisions of the rat hippocampus

Stereology is a group of mathematical and statistical methods that allows the extrapolation of three-dimensional structural information from two-dimensional sections (or slices). This allows researchers to derive important quantitative structural information, such as the volume, surface area or numbers of particular particles (e.g. cells) within defined regional boundaries. The need for such quantitative information in biology is of particular importance when evaluating the influence of various experimental treatments on specific organs, tissues and cells in the body. Knowledge of such changes has given important insights into the neural substrates that may be responsible for the functional and behavioral consequences of a disparate range of experimental treatments. Here, we describe some of these methods as applied to quantifying the total numbers of cells in defined regions of the hippocampal formation. The methods used for this evaluation were, first, the Cavalieri principle, which was used to determine the volumes of the various subdivisions of the rat hippocampus, and, second, the 'physical disector' method, which was used to estimate the numerical density of neurons within each subdivision. Once these values were derived, it was but a simple task to multiply them together to obtain estimates for the total numbers of cells in the given hippocampal region. We found that 16-and 30-day-old normal male rats had 176 800 and 152 700 pyramidal cells in the CA1 region, respectively. This decrease in the neuronal number was statistically significant. However, in the CA2 + CA3 region, there were approximately 169 300 and 149 600 pyramidal cells in 16- and 30-day-old normal male rats, respectively, which was not significantly different. In the dentate gyrus, there were approximately 36 700 neurons in the hilus region and 483 000 granule cells in the granule cell layer, irrespective of the age of the rats. There were no significant differences between these estimates of hilus neurons and granule cells.

Effects of monocular enucleation on calbindin-D 28k and c-Fos expression in the lateral geniculate nucleus in rats

The present study was undertaken to evaluate the effects of monocular enucleation on the calbindin-D 28k (CB) and c-Fos immunoreactive (IR) neurons in the lateral geniculate nucleus (LGN) complex of adult rats. The enucleation resulted in neuronal degeneration and decrease of neurons in the LGN complex. Our study demonstrated a decrease of CB-IR neuronal density on the contralateral side of the ventral (vLGN) and dorsal LGN (dLGN) until 12 weeks post-enucleation (PE). On the ipsilateral side, CB-IR neuronal density in the dLGN and vLGN showed significant and continuous decrease until 48 and 12 weeks PE, respectively. In an additional experiment, c-Fos-IR neurons were increased at 2 days PE in the vLGN with ipsilateral predominance. At 7 days, c-Fos-IR neurons on the ipsilateral vLGN were still higher than those of pre-enucleated rats. The present results suggest that monocular enucleation affects the expression of the CB and c-Fos in the LGN complex. It is indicated that these may play an important role in the neuronal degeneration and neuroplasticity of the subvisual system in rats.

Excessive testosterone treatment and castration induce reactive astrocytes and fos immunoreactivity in suprachiasmatic nucleus of mice

The suprachiasmatic nucleus (SCN) has long been recognized as the central mammalian circadian pacemaker that controls behavioral and physiological processes. The role of the SCN in circadian rhythms has been the subject of a wide range of physiological and behavioral studies, although the influence of homeostasis rhythms (such as fluctuating hormone levels) on the SCN of the hypothalamus is not entirely clear. The present study was undertaken to examine the morphological interactions between astroglial and neuronal elements in the SCN of mice after either a short-term excessive testosterone treatment (ETT) or castration, using glial fibrillary acidic protein (GFAP), and immediate early gene c-fos as well as calbindin-D28k (CB) immunohistochemistry. Both ETT and castration resulted in a significant increase in the accumulation of reactive astrocytes and Fos-imunoreactivity (IR), especially in the dorsomedial (DM) sub-region of the SCN. However, CB-IR neurons in the examined brain regions showed little change. These findings indicate that the DM sub-region of the SCN may be a possible center of hormonal regulation via a hypothalamic neuroendocrine circuit, and that a non-photic stimuli mechanism might play a role in circadian rhythm regulation.

Early maternal deprivation induces alterations in brain-derived neurotrophic factor expression in the developing rat hippocampus

The effects of maternal deprivation (MD) during early postnatal life on the brain-derived neurotrophic factor (BDNF) level were investigated in the present study. Wistar rats were assigned to either maternal deprivation or mother-reared control (MRC) groups. MD manipulation was achieved by separating rat pups from their mothers for 3h a day during postnatal days (PND) 10-15. At 16, 20, 30, and 60 days of age, the level of BDNF mRNA in the hippocampal formation of each group was determined using real-time PCR analysis. Early postnatal maternal deprivation of rat pups resulted in a significant increase in body weight at 60 days of age. The expression of BDNF mRNA in the hippocampus was significantly decreased at 16 days of age, and increased at 30 and 60 days of age. These data indicate that even a brief period of maternal deprivation during early postnatal life can affect hippocampal BDNF expression.

Parabrachial inputs to Fos-immunoreactive neurons in the lateral central nucleus of amygdala activated by hypotension: a light and electron microscopic study in the rat

Morphological features and functional implications of projections of the parabrachial nucleus to the central nucleus of the amygdala were investigated in the rat. The anatomical study was based on injections of the tracers horseradish peroxidase and biotinylated dextran amine. An extremely dense concentration of labeled fibers was found in the lateral and lateral capsular subdivisions of the central nucleus of the amygdala, originating mainly from the external lateral and ventral lateral subnuclei of the parabrachial nucleus. The parabrachial fibers exhibited the morphological characteristic of forming dense pericellular terminal arborizations. The functional implications of this pathway in cardiovascular functions were verified using Fos protein induction in response to hypotension induced by continuous intravenous administration of hydralazine-hydrochloride. In this paradigm, Fos immunoreactivity was found to be confined to the lateral and lateral capsular subdivisions of the central nucleus of the amygdala. Double immunostaining methods were used to visualize, at the electron microscopic level, terminals labeled by biotinylated dextran amine and Fos cell labeling. With this approach, we were able to confirm that Fos-immunoreactive neurons in the central nucleus of the amygdala receive axosomatic terminals from the parabrachial nucleus. The present findings point out that parabrachial inputs to the central nucleus of the amygdala play a relevant role in regulating cardiovascular function.

Colocalization of taurine and glial fibrillary acidic protein immunoreactivity in mouse hippocampus induced by short-term ethanol exposure

Morphological changes of the hippocampus were investigated in mice exhibiting signs of intoxication following short-term exposure to 6% ethanol. These alterations were examined by a double immunofluorescent study using antibodies to taurine and anti-glial fibrillary acidic protein (GFAP) antibody. Antibody-labeled taurine was localized mainly in the astrocytes and endothelial cells of control mice. Ethanol administration resulted in a significant increase in the accumulation of taurine and GFAP immunoreactivity (IR) in the stratum lacunosum-moleculare (sl-m) of the hippocampus. Specifically, the cell bodies of taurine-positive astrocytes were hypertrophied, their processes were elongated in the pericapillary region, and some colocalized with GFAP-IR cells. Furthermore, quantitative analysis revealed that the merged area in ethanol-treated mice was twice that (71.6% vs. 35.8%) of control mice. Since taurine is involved in various neuroprotective functions, the present observations suggest that the expression of taurine IR in reactive astrocytes after ethanol exposure might play an important role in neuroprotective processes.

The effect of the timing of prenatal X-irradiation on Purkinje cell numbers in rat cerebellum

Exposure of the developing brain to X-irradiation in utero is known to cause various deleterious consequences. We have previously reported the effects of prenatal X-irradiation on the development of the cerebral cortex in rats. We have now extended this study to examine the effects of such X-irradiation on the development of the cerebellum. Wistar rats were exposed to 1.5 Gy X-irradiation either on days 14, 15 or 16 of gestation (E14, E15, E16). Sham-irradiated animals were used as controls. At seven postnatal weeks of age, male rats from each group were deeply anesthetized and killed by intracardiac perfusion with 2.5% glutaraldehyde in 0.1 M phosphate buffer. The unbiased stereological procedure known as the fractionator method was used to estimate the total number of Purkinje cells in the cerebellum of each animal. Body and cerebellar weights from E14 and E15, but not E16 irradiated rats showed significant deficits compared to control animals. Rats irradiated on E16 and control rats had about 285100-304800 Purkinje cells in the cerebellum. There was no significant difference between these values. However, E14 and E15 irradiated animals had about 117500 and 196300 Purkinje cells, respectively. These estimates were significantly different from those observed in both control and E16 irradiated rats. Given that the phase of division of Purkinje cell progenitors is mainly between E14-E15 and the phase of differentiation and migration is between E16-E20, it is concluded that the vulnerable period of the Purkinje cells to X-irradiation closely overlaps the phase of division of progenitors.

Embryological consideration of drainage of the left testicular vein into the ipsilateral renal vein: analysis of cases of a double inferior vena cava

The right gonadal vein (GV=testicular vein in men, ovarian vein in women) usually drains into the inferior vena cava (IVC) while the left gonadal vein drains into the left renal vein (RV). This anatomical difference induces relatively weak haemodynamics in the left testicular vein (TV) and is considered to be a cause of a left varicocele. In textbooks on embryology, it has been documented that bilateral supracardinal veins (=origin of right and left IVC) and the subcardinal sinus (=origin of RVs and GVs) symmetrically develop during early embryogenesis. However, persistence and regression of the right and left supracardinal veins, respectively, results in drainage of the left GV into the ipsilateral RV. A double IVC (DIVC) commonly originates from a failure of disappearance of the left supracardinal vein. Although there have been a considerable number of case reports on DIVC, little attention has been paid to the anatomy of the left GV in such cases. We report here an autopsy case, a 72-year-old Japanese man, with a DIVC. This case belongs to type BC of McClure and Butler's classification. In this case, it was observed that the right TV drained into the confluence of the right IVC with the ipsilateral RV, while the left TV drained into the left RV in spite of the presence of the left IVC. This case indicates that the embryonic anastomosis point between the subcardinal sinus and the supracardinal vein on the left side is different from that on the right side. Statistical analysis of many case reports of DIVC also suggests that the bilateral supracardinal veins tend to asymmetrically anastomose with the subcardinal sinus during embryogenesis. These data imply that drainage of the left GV into the ipsilateral RV leads to regression of the left supracardinal vein but also to asymmetrical anastomosis between the supracardinal veins and the subcardinal sinus.

The effects of prenatal X-irradiation on hypoglossal nucleus: a GFAP immunohistochemical study

The effects of prenatal X-irradiation on hypoglossal (XII) nucleus were investigated in the rat. Pregnant animals were exposed to a single whole body X-irradiation on day 11 and 16 of gestation at a does of 1.3 Gy. The offspring were killed at 7-14 days of age for the histological and immunohistochemical observations. Nissl staining revealed no significant changes of XII motoneurons in these experimental animals. In the control case it was of interest that expression of glial fibrillary acidic protein-immunoreactivity (GFAP-IR) is largely confined to the dorsomedial region including the XII nucleus at the level caudal to the obex. Exposure of X-irradiation on day 16 of gestation led to similar expression of GFAP-IR in the nucleus at the same level. However, exposure on day 11 of gestation apparently led to strong expression of GFAP-IR in the XII nucleus at the level caudal to the obex and the expression was observed to extend rostrally. The GFAP-IR cells showed hypertrophy of cell bodies and longer cytoplasmic processes. Horse-radish peroxidase (HRP) injection into the tip of the tongue including the intrinsic muscles resulted in retrograde labeling in the ventromedial portion of the XII nucleus bilaterally from +0.30 to -1.25 mm. The present study would indicate that motoneurons of the XII nucleus supplying mainly the intrinsic and partly the extrinsic tongue muscles are more sensitive to X-ray exposure before the formation of the XII nucleus.

Short-term ethanol exposure alters calbindin D28k and glial fibrillary acidic protein immunoreactivity in hippocampus of mice

The effects of a short-term ethanol treatment on hippocampus have been studied in mice exhibiting intoxication signs. The alterations of neurons and astrocytes as well as quantitative changes of calbindin D28k-immunoreactivity and glial fibrillary acidic protein-immunoreactivity (GFAP-IR) in selected regions of the dorsal hippocampus were examined using anti-calbindin and anti-GFAP monoclonal anti-body (mAb), respectively. The administration of 6% (v/v) ethanol during first week led to the neuronal death and decrease of the total number of calbindin-IR neurons in the examined brain regions. Moreover, the calbindin positive neurons were shown to have diminished processes following short-term ethanol exposure. These neuronal changes were associated with the increase of the GFAP-IR astrocytes. Hypertrophy of cell bodies and cytoplasmic processes of reactive astrocytes were also seen. In addition, dense, thick and highly-stained GFAP-IR cells with long processes in granular cell layer appeared entering into molecular layer of dentate gyrus. In agreement with the discrepancy percentage of neuronal cell loss and increase of reactive astrocytes detected by calbindin and GFAP-IR using image quantitative analysis, the regional differences in the vulnerability to the neurotoxic effects following short-term ethanol exposure were found: CA3>CA2>CA1>DG. These findings also illustrate the importance of correlation between calbindin and GFAP-IR when determining the morphological alteration of neuron and astroglial following short-term ethanol treatment. The disruption of calbindin and GFAP could affect neuronal-astroglial interaction, resulting in disturbance of behaviors dependent on hippocampus.

Prenatal X-irradiation increases GFAP- and calbindin D28k-immunoreactivity in the medial subdivision of the nucleus of solitary tract in the rat

Glial fibrillary acidic protein- (GFAP) and calbindin D28k-immunoreactivity (IR) were investigated in the medial subdivision of the nucleus of the solitary tract (mNST) of prenatally X-irradiated rats. Pregnant rats were exposed to a single whole-body X-irradiation on day 11 or 16 of gestation at a dose of 1. 3 Gy. The offspring were killed at 7-14 days of age for the immunohistochemical observations. Rat pups showed strong GFAP-IR at the level rostral to the obex when receiving X-rays on day 11 of gestation, with hypertrophy of astrocyte cell bodies and cytoplasmic processes, but weak GFAP-IR when receiving X-rays on day 16 of gestation. Calbindin D28k-IR was stronger in the animals receiving X-rays on day 11 or 16 of gestation compared to that in the control animals. In the present study, the increase of GFAP- and calbindin D28k-IR cells in the mNST might indicate that adaptative mechanisms are taking place to preserve integrated nervous system function and possibly, to provide neuroprotection.

Effect of short-term ethanol exposure on the suprachiasmatic nucleus of hypothalamus: immunohystochemical study in mice

Morphological changes of the suprachiasmatic nucleus (SCN) of the hypothalamus were investigated in mice exhibiting intoxication signs of stages 2 or 3 after a short application term of 6% ethanol. Alterations in glial cells and neurons were examined using anti-glial fibrillary acidic protein (GFAP) and anti-calbindin D28k monoclonal antibody, respectively. The results revealed that short-term ethanol exposure led to strong expression of GFAP-immunoreactivity (GFAP-IR) in the dorsomedial part of the SCN. Furthermore, GFAP-IR astrocytes showed an increase in number and hypertrophy with longer processes. However, calbindin D28k-IR neurons were apparently little changed in the SCN. It is concluded that neuroadaptive response of astrocytes could occur before the neurotoxic effects emerge on neurons on the SCN.

Spermatic granulomata are experimentally induced in epididymides of mice receiving high-dose testosterone implants. I. A light-microscopical study

It is known that a spermatic granuloma is induced by the inflammatory reaction following leakage of spermatozoa outside the germ cell ducts and is the main clinical complication of vasectomy. In the present study, we found that spermatic granulomata were experimentally induced in the epididymides of mice treated with high-dose testosterone. Testosterone powder (0.02, 0.2, or 2 mg per gram body weight) was implanted into ICR male mice, which were then killed from 7 to 63 days after the treatment for histological examination at the light-microscopic level. The results showed that the testis exhibited little or no degenerative change; however, the epididymides were frequently affected by spermatic granulomata after day 35 in mice implanted with high-dose testosterone (2 but not 0.2 or 0.02 mg per gram body weight). Observation of the early histological changes revealed that the ductal epithelium of the epididymides became vacuolated around day 25. Thereafter, the basement membrane of the epididymal ducts was ruptured after day 30, followed by leakage of spermatozoa into the adjacent interstitial tissue. The extravasated spermatozoa were then surrounded by macrophages (= epithelioid cells) and lymphocytes, resulting in the formation of a spermatic granuloma. In contrast, other mice treated with the same dose of deoxycorticosterone or estradiol did not show the induction of spermatic granulomata. Therefore, this study demonstrated that a spermatic granuloma is specifically formed in the epididymis by testosterone and that the lesion is started by vacuolation of the epididymal duct epithelium.

Topographical uptake of blood-borne horseradish peroxidase (HRP) in the murine testis at the light microscopic level

Light microscopical studies on the uptake of blood-borne horseradish peroxidase (HRP) in large areas of the testis have been scarce because of the difficulty of staining HRP in testes with well-preserved morphology. However, observation of exogenous HRP in all areas of the testis enables detection of regional tissue injury induced by toxic chemicals or immunization. In the present study, the localization of blood-borne HRP in the murine testis was investigated light microscopically using plastic-embedded testes and post-embedding histochemical methods. Mice were injected intravenously with HRP, and then perfused with 2.5% glutaraldehyde and 3% paraformaldehyde in 0.1 M phosphate buffer. The fixed testes were immediately removed, dehydrated, and then embedded in plastic without cutting them into small pieces. The prepared sections treated by the diaminobenzidine method exhibited intense HRP activity with well-preserved testis morphology. It was noted that many interstitial macrophages had endocytosed HRP. In particular, HRP-endocytosing macrophages were concentrated around the tubuli recti. The testicular capsule, containing many lymphatic capillaries and vessels, was also loaded with HRP. In the subcapsular interstitium, free HRP in the lymph space accumulated, but the staining intensity was weak compared to that in testicular macrophages. No HRP infiltration into the lumen of the seminiferous tubules was observed at the light microscope level; however, HRP staining was detected in tubular walls and epithelial cells lining the rete testis and tubuli recti, indicating that these regions are permeable to HRP.