Circadian rhythms of slow-wave sleep and paradoxical sleep are in opposite phase in genetically hypoprolactinemic rats

In eleven genetically hypoprolactinemic rats (IPL nude rats) and five control rats (OFA), the sleep-waking cycle was continuously registered for 14 days at two ambient temperatures. At 23 degrees C, the slow wave sleep (SWS) duration of IPL rats was significantly higher (+6.8%, t = 5.4, p less than 0.001) than that of control rats, while the paradoxical sleep (PS) duration was lowered by 31.8% (t = 9.4, p less than 0.001). The circadian rhythm of PS disappeared while that of SWS persisted unchanged. At 30 degrees C, both sleep durations reached the level of control rats. The circadian rhythm of PS was however completely reversed: the PS acrophase was at 01 h while that of SWS was at 12 hrs. This first observation of spontaneous dissociation of the two states of sleep supports the hypothesis of two distinct circadian clocks, one for SWS, another for PS. It is suggested that hypothalamic prolactin and/or other still unknown genetic alterations might be responsible for the observed change in the PS circadian rhythm.     

Brain free fatty acids, edema, and mortality in gerbils subjected to transient, bilateral ischemia, and effect of barbiturate anesthesia

Brain free fatty acids (FFAs) and brain water content were measured in gerbils subjected to transient, bilateral cerebral ischemia under brief halothane anesthesia (nontreated group) and pentobarbital anesthesia (treated group). Mortality in the two groups was also evaluated. In nontreated animals, both saturated and mono- and polyunsaturated FFAs increased approximately 12-fold in total at the end of a 30-min period of ischemia; during recirculation, the level of free arachidonic acid dropped rapidly, while other FFAs gradually decreased to their preischemic levels in 90 min. In treated animals, the levels of total FFAs were lower than the nontreated group during ischemia, but higher at 90 min of reflow, and the decrease in the rate of free arachidonic acid was slower in the early period of reflow. Water content increased progressively during ischemia and recirculation with no extravasation of serum protein, but the values were consistently lower in the treated group. None of the nontreated animals survived for 2 weeks; in contrast, survival was 37.5% in the treated group. It is suggested that barbiturate protection from transient cerebral ischemia may be mediated by the attenuation of both membrane phospholipid hydrolysis during ischemia and postischemic peroxidation of accumulated free arachidonic acid.     

The ontogeny and physiology confirms the dual nature of sleep states

In the Jouvet's laboratory, as early as 1960 the study of the ontogenesis of paradoxical sleep (PS) named "sleep 'with jerks" began in the kitten and led to the first publication in 1961. Then, several species were studied, lamb, rat, human neonates, etc. These works showed that at birth sleep with jerks was preponderant in altricial (immature) species (cat, rat) and the first to appear during the second half of gestation in precocious species (guinea pig). For Jouvet, sleep with jerks is a immature form of PS. Why PS is so important at birth? The maturation of the central nervous system, based on the myelinization, starts in the spinal cord then forwards to the brainstem and forebrain. So, PS mechanisms located in the brainstem are the first to mature and the only one to function. Then the slow wave sleep (SWS) and waking structures become mature. Phylogenetic studies showed that in mammals and birds PS was present even in marsupials and monotremes. Until now only the one exception is the dolphin with a voluntary breathing. To sleep and breath, dolphin has developed an unilateral sleep without classical PS. In other animals, reptiles, amphibians, fishes, PS was not observed with the parameters used in mammals. The study at birth (not yet done) of reptiles would allow perhaps the observation of a temporary PS. Based on these findings, a schematic model of the sleep regulation can be elaborated. Haeckel's aphorism "Ontogeny recapitulates phylogeny" seems true for PS which appears in birds and mammals i.e. at the end of evolution as it appears at the end of gestation when PS cerebral structures are present and mature.     

Involvement of peripheral type of benzodiazepine receptor in social isolation stress-induced decrease in pentobarbital sleep in mice

Our previous studies have shown that central-type benzodiazepine (BZD) receptors (CBR) and neurosteroids capable of modulating GABA(A) receptor function are involved in the decrease of pentobarbital (PB)-induced sleep caused by social isolation stress in mice. In this study, to further clarify the mechanism underlying this decrease, we investigated the possible involvement of peripheral-type BZD receptors (PBR) which play an important role in neurosteroidogenesis in PB sleep in socially isolated mice. Socially isolated mice showed significantly shorter duration of PB-induced sleep than group-housed animals. When injected intracerebroventricularly (i.c.v.), FGIN-1-27 (FGIN, 25-100 nmol), a selective PBR agonist, and PK11195 (PK, 14-28 nmol), a PBR antagonist, and pregnenolone (PREG, 15-30 nmol), a neurosteroid precursor, dose-dependently normalized the PB sleep in isolated mice without having an effect on the group-housed animals. In contrast, pregnenolone sulfate (PS, 24 nmol), an endogenous neurosteroidal negative allosteric modulator of the GABA(A) receptor, reduced PB sleep in group-housed but not isolated mice. PS, at the same dose, significantly attenuated the effects of FGIN (100 nmol), PK (28 nmol) and PREG (30 nmol) in isolated mice, while FGIN (100 nmol), PK (28 nmol) and pregnenolone (30 nmol) significantly blocked the effect of PS (24 nmol) in group-housed mice. These results suggest that the PBR-mediated decrease in the genesis of neurosteroid(s) possessing a GABA(A) receptor agonistic profile is also partly involved in the down regulation of the GABA(A) receptor following long-term social isolation and contributes to the decrease of PB-induced sleep in isolation stressed mice.     

Annexin-V promotes anti-tumor immunity and inhibits neuroblastoma growth in vivo

The goal of the current study is to determine the effects of blocking phosphatidylserine (PS) on the growth of neuroblastoma in mice. PS, an anionic phospholipid restricted to the cytoplasmic surface of plasma membranes in most cells, is externalized to the surface of apoptotic cells. PS has been shown to induce immune tolerance to self-antigens. PS can also be found on the surface of live cells and in particular tumor cells. Annexin-V (AnV) is a protein that specifically binds and blocks PS. To determine the effects of blocking PS with AnV on tumor growth and immunogenicity, mice were inoculated with AGN2a, a poorly immunogenic murine neuroblastoma that expresses high level of PS on the cell surface. Survival and anti-tumor T cell response were determined. AGN2a were engineered to secrete AnV. Secreted protein effectively blocked tumor PS. 40?% of mice inoculated with AnV-expressing AGN2a cells survived free of tumor, whereas none of the mice inoculated with control cells survived (p?=?0.0062). The benefits of AnV were lost when mice were depleted of T cells. The findings suggest that AnV could protect mice from tumor challenge through an immune mediated mechanism. Mice were then immunized with irradiated AnV-secreting or control cells, and challenged with wild-type AGN2a cells. AnV-secreting cell vaccine protected 80?% of mice from AGN2a challenge, while control cell vaccine prevented tumor growth in only 30?% of animals (p?=?0.012). ELISPOT analysis demonstrated that AnV-secreting cell vaccine induced a greater frequency of interferon-gamma producing splenic T cells. T cells isolated from mice immunized with AnV-secreting but not control vaccine lysed AGN2a. In summary, AnV blocked PS, enhanced T cell mediated tumor immunity, and inhibited tumor growth.     

The role of prostaglandins in the antiarrhythmic effect of ischemic preconditioning

The role of prostaglandins in the antiarrhythmic effect of ischemic preconditioning (IP) was investigated in pentobarbital-anesthetized rats. In 5 unpreconditioned control rats, 30 min of occlusion of the left coronary artery elicited ventricular tachycardia (VT) and fibrillation (VF), with an average duration of VT and VF of 51 +/- 6 and 43 +/- 4 s, respectively. Frequent ventricular premature beats (VPBs; average 1,249 +/- 145) were also documented in these animals. Thirty minutes of reperfusion after the prolonged coronary occlusion in these animals caused more severe arrhythmias, including irreversible VF. In animals pretreated with IP (n = 5), which was achieved by 3 cycles of 3 min of occlusion followed by 5 min of reperfusion, 30 min of coronary artery occlusion caused neither VT nor VF, but occasional VPBs (average 2 +/- 1, p < 0.001 vs. control). Only occasional VPBs were observed during 30 min of reperfusion in this group. In animals pretreated with indomethacin (1 mg/kg i.v., n = 5) followed by IP, prolonged ischemia and reperfusion led to frequent VPBs but no VT or VF. The average number of VPBs during ischemia and reperfusion in this indomethacin-treated group was less than that of the controls but greater than the IP-only group (p < 0.01). In conclusion, prostaglandins appear to play a role in the protective effect of IP against VPBs during acute ischemia and reperfusion.     

The effect of motion sickness on the sleep–wake cycle in rats exposed to prenatal hypoxia

This study is a follow-up to our previous research of the phenomenology and mechanisms of motion sickness (MS) and its relationship with changes in the sleep–wake cycle (SWC). We report data on the effect of MS on the SWC in 30-day-old intact rats and those exposed to prenatal hypoxia on days 13 and 19 of gestation. In all animal groups, MS was shown to decrease significantly the waking time and increase that of paradoxical sleep (PS). A link between hypothalamic MS and SWC regulatory mechanisms was revealed, and the role of this teamwork in the development of the sopite syndrome, which may be a sole manifestation of MS in some animals and man, was suggested. It was established that hypoxic exposure on day 19 of gestation had a greater damaging effect on the thalamocortical sleep-regulating structures than that on day 13, when it is only the hypothalamic-hippocampal slow-sleep regulatory systems that were found to be affected. Against this background, MS appreciably suppresses the brain excitatory systems that maintain wakefulness (supposed to be the ascending reticular activating system) and enhances those activating systems that regulate PS. It is exactly prenatal hypoxic exposure of rats on day 19 of gestation that enabled demonstrating the role of the evolutionarily young thalamocortical system in PS control.     

The estimation of the nitric oxide role in the aggravation of combined radiation-thermal injuries

The influence of specific inhibitor of inducible NO synthase S-ethil-isothiourea (as "Difetur" preparation) on liver NO production level, and 30-days survival, mean survival time and probability of mortality within animals under combined radiation/thermal injury (CRTI) were evaluated. Experiments were carrying out on mice (whole body gamma-irradiation at the dose of 7 Gy + 10% body surface full-thickness thermal burn). It was shown, that CRTI induce 2-fold statistical significant increase of NO production in liver of experimental animals. Mice pretreatment with Difetur preparation lead to practically full inhibition of NO production. In the group of animals, with Difetur administration during first two days after CRTI 60% mice survived as compared 15% survive in control group. In pair with data on probability of mortality it was suggested that growth of NO production in the early period of CRTI increase sensitivity of animals to pathological processes leading to death on 10-12 days.     

The features of sleep homeostasis in pregnant rats

To investigate the effects of short-term sleep deprivation on the sleep pattern during pregnancy, cortical and hippocampal EEG and locomotor activity were recorded within 24-hours in a "disk-over-water" paradigm in 18 Wistar rats. Rats were adapted to experimental situation and were able to move across the rotating disk without falling in water. Then a polysomnogram was recorded for 3 sequential days in the control group 1 (n = 12) without disk rotation. On the next day non-pregnant rats (experimental group 1, n = 6) were subjected to the sleep deprivation procedure with a pre-set program of disk rotation from 11:00 to 14:00 during 3 sequential days. Other 6 rats (experimental group 2) were subjected to sleep deprivation on the 5-7th day of pregnancy. EEG and locomotor activity were also constantly recorded during the sleep deprivation procedure. In control group 2 (n = 6, without sleep deprivation), a polysomnogram was recorded on the 5-7th day of pregnancy. As compared to non-pregnant rats, sleep intensity of pregnant rats increased during the first hours after the deprivation, and a considerable rebound of REM sleep took place. Sleep pattern during the off-light 12 hours remained unchanged. The results suggest that homeostatic compensation of sleep deprivation effects in rats on the first week of pregnancy is more efficient than in control non-pregnant animals.     

Increase of paradoxical sleep, induced by injection of ibotenic acid in the ventrolateral posterior hypothalamus in the cat

The intratissular injection of ibotenic acid into the ventrolateral part of the posterior hypothalamus induced a dramatic biphasic and transient hypersomnia immediately after disappearance of the anaesthesia (14 to 24 hrs. after injection). The duration of hypersomnia was related to the dose of neurotoxin injected. Its first period was characterized by an increase in paradoxical sleep (PS) (300%). Then, during the second phase, PS disappeared and there was a subsequent increase of slow wave sleep (SWS) (60%). Finally, on the third day, all cats recovered control level of PS and SWS.     

Cerebral Phospholipid Content and Na+, K+-ATPase Activity During Ischemia and Postischemic Reperfusion in the Mongolian Gerbil

Using bilateral carotid artery occlusion in adult gerbils we examined the effects of ischemia and ischemia/reperfusion on cerebral phospholipid content and Na+,K+-ATPase (EC 3.6.1.3) activity. In contrast to the large changes in phospholipid content and membrane-bound enzyme activity that have been observed in liver and heart tissues, we observed relatively small changes in the cerebral content of total phospholipid, phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylethanolamine (PE) following ischemic intervals of up to 240 min. Following 15 min of ischemia the cerebral content of sphingomyelin (SM) was decreased to less than 50% of control values but returned to near-normal levels with longer ischemic periods. Significant decreases in the cerebral content of phosphatidylinositol (PI) and phosphatidic acid (PA) were observed following shorter intervals of ischemia (15-45 min). Na+,K+-ATPase activity of cerebral homogenates prepared from the brains of gerbils subjected to 30-240 min of ischemia was decreased but significantly different from control activity only after 30 min of ischemia (-29%, p less than or equal to 0.05). With the exception of PS, reperfusion for 60 min following 60 min of ischemia resulted in marked increases in cerebral phospholipid content with PC, SM, PI, and PA levels exceeding and PE levels equal to preischemic values. Longer periods of reperfusion (180 min) resulted in decreases in cerebral phospholipid content toward (PC, SM, PI, and PA) or below (PE) preischemic levels. In contrast, the cerebral content of PS significantly decreased during reperfusion (-51% at 60 min, p less than or equal to 0.05) and remained below preischemic values even after 180 min of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of adrenal steroids and their reduced metabolites on hippocampal long-term potentiation

We studied the effects of steroid hormones on the hippocampal long-term potentiation (LTP), a putative mechanism of neuronal plasticity and memory storage in the CNS. In vivo experiments were performed in rats under chloral hydrate anesthesia (0.4 mg/kg i.p.). All animals were adrenalectomized 48 h before recording. LTP was induced after priming tetanic stimulation at the perforant pathway (PP) and single pulse field potentials were obtained from the dentate gyrus (DG). The excitatory post-synaptic potential (EPSP) slope and population spike (PS) amplitude were analyzed before and after the i.v. injection of the steroids and after the induction of LTP, and followed up to 1 h. Results obtained with the hormones were compared with matched control animals injected with vehicle alone, Nutralipid 10%. Previous results from our laboratory showed that deoxycorticosterone (DOC) decreased the magnitude of the EPSP at all times after priming stimulation and the PS decreased during the first 30 min of the LTP. Corticosterone decreased the EPSP in the first 15 min and the PS during the first 30 min after priming stimuli. In these experiments the mineralocorticoids aldosterone and 18-OH-DOC elicited a decrease of the EPSP at all times post-train; and no significant difference against vehicle was observed in the PS. Post-injection values were not changed except for 18-OH-DOC at a dose of 1 mg, where a decrease of both the EPSP (P less than 0.01) and the PS (P less than 0.02) was observed against vehicle. ATH-progesterone at 0.1 mg/rat also decreased the EPSP values significantly after priming stimulation and no significant changes against vehicle were observed in the PS. These results show that adrenal steroids can modulate hippocampal LTP, that they can act at different neuronal loci and with different time courses in the development of the phenomena.     

Effects of electrolytic lesion of hypothalamic paraventricular nucleus and its related areas on the sleep waking cycle in the cat

In order to study putative hypothalamic mechanisms of sleep waking cycle regulation we destroyed, by electrolytic coagulation, a large part of the medial hypothalamus overlapping the paraventricular nucleus in 6 adult cats. We never observed any modification of light slow wave sleep. Three of the six cats presented no paradoxical sleep (PS) impairment, despite an almost total destruction of neurophysin-immunoreactive cells of PVN in two cats and marked signs of diabetes insipidus in the third. Further, in the other three animals a statistically significant decrease of daily quantities of PS and deep slow wave sleep (SWS2) were related to an extensive destruction of the anterior hypothalamic area. These results suggest lack of influence of the PVN in sleep regulation and an involvement of the anterior hypothalamus in the onset of SWS2 and PS.     

A Prosaposin-Derived Peptide Alleviates Kainic Acid-Induced Brain Injury

Four sphingolipid activator proteins (i.e., saposins A–D) are synthesized from a single precursor protein, prosaposin (PS), which exerts exogenous neurotrophic effects in vivo and in vitro. Kainic acid (KA) injection in rodents is a good model in which to study neurotrophic factor elevation; PS and its mRNA are increased in neurons and the choroid plexus in this animal model. An 18-mer peptide (LSELIINNATEELLIKGL; PS18) derived from the PS neurotrophic region prevents neuronal damage after ischemia, and PS18 is a potent candidate molecule for use in alleviating ischemia-induced learning disabilities and neuronal loss. KA is a glutamate analog that stimulates excitatory neurotransmitter release and induces ischemia-like neuronal degeneration; it has been used to define mechanisms involved in neurodegeneration and neuroprotection. In the present study, we demonstrate that a subcutaneous injection of 0.2 and 2.0 mg/kg PS18 significantly improved behavioral deficits of Wistar rats (n = 6 per group), and enhanced the survival of hippocampal and cortical neurons against neurotoxicity induced by 12 mg/kg KA compared with control animals. PS18 significantly protected hippocampal synapses against KA-induced destruction. To evaluate the extent of PS18- and KA-induced effects in these hippocampal regions, we performed histological evaluations using semithin sections stained with toluidine blue, as well as ordinal sections stained with hematoxylin and eosin. We revealed a distinctive feature of KA-induced brain injury, which reportedly mimics ischemia, but affects a much wider area than ischemia-induced injury: KA induced neuronal degeneration not only in the CA1 region, where neurons degenerate following ischemia, but also in the CA2, CA3, and CA4 hippocampal regions.     

L-propionylcarnitine and myocardial performance in stunned porcine myocardium

Recently, we showed that L-propionylcarnitine did not affect recovery of regional contractile function of porcine myocardium subjected to 1 h of low-flow ischemia followed by 2 hr of reperfusion. In that study, ischemia may have been too severe and/or the duration of reperfusion too short to detect a beneficial effect of the compound. Therefore, in the present study we investigated the effects of saline (control group; n = 14) or pretreatment with L-propionylcarnitine (3 days of 50 mg/kg p.o. b.i.d. + 50 mg/kg i.v. prior to the experiment; n = 13) on recovery of regional contractile function of the myocardium in open-chest anesthetized pigs, subjected to two cycles of 10 min of left anterior descending coronary artery (LADCA) occlusion, each followed by 30 min of reperfusion. In the control animals, at the end of the second reperfusion period, systemic vascular resistance had increased by 18%, which, however, was not observed in the L-propionylcarnitine-treated pigs. In the control group, during the first occlusion, systolic segment length shortening (SSLS) of the LADCA-perfused area decreased from 18.5 ± 5.5% to - 3.7 = 3.2%. After 30 min of reperfusion, SSLS of the LADCA-perfused area had only partially recovered to 6.2 ±5.9%. During the second occlusion-reperfusion cycle similar values for SSLS were observed. In the treated animals., SSLS of the LADCA-perfused area was slightly improved after the second occlusion-reperfusion cycle (p = 0.056). This effect did not result in an overall improvement in cardiac pump function. We conclude that in a model of myocardial stunning, L-propionylcarnitine prevents systemic vasoconstriction in response to ischemia and reperfusion and, possibly as a result of this effect, slightly ameliorates post-ischemic hypofunction. (Mol Cell Biochem116: 147–153, 1992)     

The effects of smoking on experimental skin flaps in hamsters

To study the effects of the inhalation of cigarette smoke on the survival of skin flaps, 30 Syrian Golden hamsters were divided into three groups of 10. Two of these groups were acclimatized to cigarette smoke in increasing increments for 9 weeks in standard Hamburg I smoking cages. The third group of 10 (group A) served as controls and were sham-smoked throughout the experiment. After acclimatization, one group of 10 (group B) was smoked for a further 6 weeks. A standard axial-pattern flap was then raised on the dorsum of the animals. Ten animals in group C were smoked for 6 weeks preoperatively and for 2 weeks postoperatively, at which time the animals in all groups were sacrificed. All animals survived the experiment. The flaps in control group A all survived without necrosis. Two of the 10 dorsal flaps sustained terminal necrosis in group B animals. Six of the 10 flaps resulted in significant terminal necrosis in group C animals. Statistical analysis of the results indicated a significant comparison between control group A and group C of those animals smoked throughout the experiment. We conclude from this experiment that the inhalation of cigarette smoke consistent with that of a heavy smoker (2 packs per day) has an adverse effect on wound healing of skin flaps in hamsters. Apparently, cessation of smoking even at the time of surgical preparation of the flap obviates much of the noxious effect and increase flap survival significantly.     

NADPH-diaphorase expression in the rat jejunum after intestinal ischemia/reperfusion

The purpose of this study was to analyze the nicotinamide adenine dinucleotide phosphate - diaphorase (NADPH-d) activity in the rat jejunum after a mesenteric ischemia/reperfusion injury. Nitric oxide, synthetised from L-arginine by the enzyme nitric oxide synthase, is a nonadrenergic noncholinergic relaxant neurotransmitter of the intestinal smooth muscle. It plays an important role in the process of plasticity after the ischemia/reperfusion injury. Experimental animals were divided in two groups: the control group and the ischemic/reperfusion group, with different period of the reperfusion. The NADPH-d histochemical method has been used as a marker for the nitric oxide synthase. NADPH-d activity has been rapidly decreased in the neurons of both enteric nervous systems in plexuses of the jejunum after 1 h mesenteric ischemia and 1 h reperfusion. Differences were predominantly detected in the myenteric plexus; they were seen in change of the neuronal shape, in the arrangement of neurons and in intensity of their staining. The NADPH-d positivity was absent in the intestinal crypts. After 1 h ischemia and 24 h reperfusion, the NADPH-d activity was gradually increased, but it was lower in comparison with the control group. On the 30th day following the ischemia/reperfusion there were no changes in NADPH-d positivity compared with the control animals. These results indicated that the jejunal ischemia/reperfusion has affected the neurons of the enteric nervous system of adult rats and resulted in the early decrease of NADPH-d positivity 1 h of the reperfusion insult. The gradual increasing of NADPH-d activity in 24 h following the reperfusion could be considered as a result of the plasticity process. On the 30(th) day after the ischemia/reperfusion all histochemical changes were returned to the control levels.     

Increase of paradoxical sleep induced by microinjections of ibotenic acid into the ventrolateral part of the posterior hypothalamus in the cat

In order to study putative hypothalamic mechanisms of sleep-waking cycle regulation we injected a neural cell body toxin--ibotenic acid (IBO), 40 to 200 micrograms--into the ventrolateral part of the posterior hypothalamus (HVL). This injection induced a dramatic biphasic and transient hypersomnia immediately after the disappearance of the anesthesia (14 to 24 hours after the injection). The duration of hypersomnia was dose dependent. Its first period was characterized by an increase in paradoxical sleep (PS) (300%). Then, during the second phase, PS disappeared and there was a subsequent increase of slow sleep (SWS) (60%). Finally, on the third day, all cats recovered control level of PS and SWS while, 3 weeks later, the histological analysis revealed the great loss of cell bodies in the HVL in all cats.     

侧脑室注射促甲状腺激素释放激素对大鼠睡眠—觉醒的影响

采用多导睡眠描记术研究了例脑室注射促甲状腺激素释放激素(TRH)对正常大鼠和去甲状腺大鼠睡眠-觉醒的影响。在正常大鼠,TRH引起觉醒增加,浅慢波睡眠(SWS_1)、深慢波睡眠(SWS_2)和总睡眠时间(TST)均减少,异相睡眠(PS)消失,SWS_1、SWS_2和PS的潜伏期均显著延长,给药后立即产生效应并在1h内达高峰。去甲状腺对大鼠的睡眠-觉醒无明显影响,注射TRH后引起的效应与正常大鼠相似。结果提示TRH有促进大鼠觉醒的作用,对各睡眠时相均有抑制作用,其作用部位可能在下丘脑以外的中枢结构。     

Stobadine protects against ischemia-reperfusion induced morphological alterations of cerebral microcirculation in dogs

Vascular diseases of the CNS are a major medical, social and economic problem. From the number of causes leading to nervous malfunction and damage, ischemia is most prominent. Thus, neuronal protection from ischemic damage may provide significant preventive and treatment potential. This study was designed to test possible protective effects of stobadine in a canine model of global cerebral ischemia. Seven minute ischemia was induced by four vessel ligation and maintained using a controlled systemic hypotension. Stobadine pretreated animals were infused with 2 mg/kg stobadine 30 minutes prior to ischemia, while control animals received vehicle. After a 24 hour reperfusion phase, animals were perfusion-fixed and evaluated using electron microscopy. Stobadine pretreated dogs showed much less damage to both endothelial lining and pericapillary structures of the blood-brain barrier. This included preservation of cellular shape of the endothelium, patency of microvessels, lack of intraluminal blebs material, near normal cytoplasmic osmiophilia, decreased thickness of endothelial basement membrane, significantly less edema of astrocyte end-feet, and preservation of fine mitochondrial structure compared to the control group. Ischemic neuronal changes were observed less frequently in the stobadine pretreated group. In summary, we conclude that stobadine protects both cerebral microcirculation and neurons from injury induced by global cerebral ischemia and reperfusion.