Reactive oxygen species downregulate dystroglycans in the megakaryocytes of rats with arterial hypertension.

Hypertension is a multifactorial disease characterized by vascular and renal dysfunction, cardiovascular remodeling, inflammation, and fibrosis, all of which are associated with oxidative stress. We previously demonstrated cellular reactive oxygen species (ROS) imbalances may impact the structural and biochemical functions of blood cells and reported downregulation of ß-dystroglycan (ß-Dg) and overexpression of the epithelial sodium channel (ENaC) contribute to the pathophysiology of hypertension. In this study, we aimed to determine the expression of dystroglycans (Dg) and ENaC in platelet progenitors (megakaryocytes) and their surrounding niches. Thin sections of bone marrow from 5- and 28-week-old spontaneous hypertensive rats (SHR) were compared to age-matched normotensive rats (WKY). Cytometry and immunohistochemical assays demonstrated an oxidative environment in SHR bone marrow, characterized by high levels of myeloperoxidase and 3-nitrotyrosine and downregulation of peroxiredoxin II. In addition, transmission electron micrography and confocal microscopy revealed morphological changes in platelets and Mgks from SHR rats, including swollen mitochondria. Quantitative qRT-PCR assays confirmed downregulation of Dg mRNA and immunohistochemistry and western-blotting validated low expression of ß-Dg, mainly in the phosphorylated form, in Mgks from 28-week-old SHR rats. Moreover, we observed a progressive increase in ß-1 integrin expression in Mgks and extracellular matrix proteins in Mgk niches in SHR rats compared to WKY controls. These results indicate accumulation of ROS promotes oxidative stress within the bone marrow environment and detrimentally affects cellular homeostasis in hypertensive individuals.

Development of the hypersecretory phenotype in the population of adrenal chromaffin cells from prehypertensive SHRs.

The hypersecretory phenotype of adrenal chromaffin cells (CCs) from early spontaneously hypertensive rats (SHRs) mainly results from enhanced Ca2+-induced Ca2+-release (CICR). A key question is if these abnormalities can be traced to the prehypertensive stage. Spontaneous and stimulus-induced catecholamine exocytosis, intracellular Ca2+ signals, and dense-core granule size and density were examined in CCs from prehypertensive and hypertensive SHRs and compared with age-matched Wistar-Kyoto rats (WKY). During the prehypertensive stage, the depolarization-elicited catecholamine exocytosis was ~ 2.9-fold greater in SHR than in WKY CCs. Interestingly, in half of CCs the exocytosis was indistinguishable from WKY CCs, while it was between 3- and sixfold larger in the other half. Likewise, caffeine-induced exocytosis was ~ twofold larger in prehypertensive SHR. Accordingly, depolarization and caffeine application elicited [Ca2+]i rises ~ 1.5-fold larger in prehypertensive SHR than in WKY CCs. Ryanodine reduced the depolarization-induced secretion in prehypertensive SHR by 57%, compared to 14% in WKY CCs, suggesting a greater contribution of intracellular Ca2+ release to exocytosis. In SHR CCs, the mean spike amplitude and charge per spike were significantly larger than in WKY CCs, regardless of age and stimulus type. This difference in granule content could explain in part the enhanced exocytosis in SHR CCs. However, electron microscopy did not reveal significant differences in granule size between SHRs and WKY rats' adrenal medulla. Nonetheless, preSHR and hypSHR display 63% and 82% more granules than WKY, which could explain in part the enhanced catecholamine secretion. The mechanism responsible for the heterogeneous population of prehypertensive SHR CCs and the bias towards secreting more medium and large granules remains unexplained.

Calcium signaling and expression of voltage-gated calcium channels in the mouse ovary throughout the estrous cycle†.

The estrous cycle is an iterative change in the anatomy, endocrinology, physiology, and behavior to provide maximum fecundity. Ovarian steroid production involves gonadotropin-induced [Ca2+]i raises due in part to voltage-gated Ca2+ channels (VGCCs) whose identity and tissue distribution in situ is largely unknown. Using fluorescence Ca2+ imaging and confocal microscopy, we recorded both spontaneous and depolarization-induced Ca2+ signals in living mouse ovarian slices. They were most prominent in theca cells (TCs) and oocytes. The presence of Ca2+ channel subunits CaV 1.2, CaV 1.3, CaV 2.1, CaV 2.2, and CaV 3 was examined with immunofluorescence of ovarian sections. CaV 1.2 and CaV 1.3 (L-type Ca2+ channels) are present in the stroma, granulosa cells (GCs), and corpora lutea (CL). Intriguingly subunits that are characteristic of nerve cells are also expressed: P/Q-type (CaV 2.1; α1A) in the stroma and CL cells and N-type (CaV 2.2; α1B) in perifollicular smooth muscle cells. The expression of α1 subunits fluctuates along the estrous cycle: in metestrus-diestrus (the quiescent stage of the cycle), CL and GCs are similarly stained, while in proestrus (stage of maximal ovarian stimulation) CL staining increases relatively to GCs. Also in proestrus, CaV 3 Ca2+ channel subunits are expressed more in CL compared to GC suggesting a more significant role of Ca2+ channels. In estrus, CaV 3 subunits from mesenchymal and interfollicular stromal cells become intensely stained. Our study represents an important step in understanding the role of VGCCs in ovarian physiology and possibly in ovarian cancer and other reproductive pathologies.

Mouse embryonic stem cell-derived cells reveal niches that support neuronal differentiation in the adult rat brain.

A neurogenic niche can be identified by the proliferation and differentiation of its naturally residing neural stem cells. However, it remains unclear whether "silent" neurogenic niches or regions suitable for neural differentiation, other than the areas of active neurogenesis, exist in the adult brain. Embryoid body (EB) cells derived from embryonic stem cells (ESCs) are endowed with a high potential to respond to specification and neuralization signals of the embryo. Hence, to identify microenvironments in the postnatal and adult rat brain with the capacity to support neuronal differentiation, we transplanted dissociated EB cells to conventional neurogenic and non-neurogenic regions. Our results show a neuronal differentiation pattern of EB cells that was dependent on the host region. Efficient neuronal differentiation of EB cells occurred within an adjacent region to the rostral migratory stream. EB cell differentiation was initially patchy and progressed toward an even distribution along the graft by 15-21 days post-transplantation, giving rise mostly to GABAergic neurons. EB cells in the striatum displayed a lower level of neuronal differentiation and derived into a significant number of astrocytes. Remarkably, when EB cells were transplanted to the striatum of adult rats after a local ischemic stroke, increased number of neuroblasts and neurons were observed. Unexpectedly, we determined that the adult substantia nigra pars compacta, considered a non-neurogenic area, harbors a robust neurogenic environment. Therefore, neurally uncommitted cells derived from ESCs can detect regions that support neuronal differentiation within the adult brain, a fundamental step for the development of stem cell-based replacement therapies.

Enhanced Ca(2+)-induced Ca(2+) release from intracellular stores contributes to catecholamine hypersecretion in adrenal chromaffin cells from spontaneously hypertensive rats.

Adrenal chromaffin cells (CCs) from spontaneously hypertensive rats (SHRs) secrete more catecholamine (CA) upon stimulation than CCs from normotensive Wistar Kyoto rats (WKY). Unitary CA exocytosis events, both spontaneous and stimulated, were amperometrically recorded from cultured WKY and SHR CCs. Both strains display spontaneous amperometric spikes but SHR CCs produce more spikes and of higher mean amplitude. After a brief stimulation with high K(+) or caffeine which produces voltage-gated Ca(2+) influx or intracellular Ca(2+) release, respectively, more spikes and of greater mean amplitude and unitary charge were recorded in SHR CCs. Consequently, peak cumulative charge was ~2-fold higher in SHR CCs. Ryanodine (10 µM), a specific blocker of the ryanodine receptors reduced depolarization-induced peak cumulative charge by ~10 % in WKY and ~77 % in SHR CCs, suggesting, a larger contribution of Ca(2+)-induced Ca(2+) release to CA exocytosis in SHR CCs. Accordingly, Ca(2+) imaging showed larger [Ca(2+)]i signals induced both by depolarization and caffeine in SHR CCs. Distribution amplitude histograms showed that small amperometric spikes (0-50 pA) are more frequent in WKY than in SHR CCs. Conversely, medium (50-190 pA) and large (190-290 pA) spikes are more numerous in SHR than in WKY CCs. This study reveals that the enhanced CA secretion in SHR CCs results from a combination of (1) larger depolarization-induced Ca(2+) transients, due to a greater Ca(2+)-induced intracellular Ca(2+) release, (2) more exocytosis events per time unit, and (3) a greater proportion of medium and large amperometric spikes probably due to a higher mean CA content per granule. Enhanced CA release by excessive amplification by Ca(2+) induced Ca(2+) release and larger granule catecholamine content contributes to the increased CA plasma levels and vasomotor tone in SHRs.

Role of glutamate receptors in the dorsal reticular nucleus in formalin-induced secondary allodynia.

The role of glutamate receptors present in the medullary dorsal reticular nucleus (DRt) in the formalin test and formalin-induced secondary nociception was studied in rats. Secondary mechanical allodynia was assessed with von Frey filaments applied to the rat's hindpaw, and secondary thermal hyperalgesia was evaluated with the tail-immersion test. The selective glutamate receptor antagonists MK801 (N-methyl-D-aspartate receptor antagonist), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (AMPA/KA receptor antagonist) and A841720 (metabotropic glutamate 1 receptor antagonist) were injected into the DRt before or 6 days after formalin injection in the rat. In the formalin test, the three antagonists significantly reduced the number of flinches in both phases of the test. DRt microinjection of MK801 or A841720, but not of CNQX, reduced both secondary nociceptive behaviors. Moreover, pre-treatment with the three antagonists injected into the DRt prevented the development of secondary mechanical allodynia and secondary thermal hyperalgesia. Similarly, in these rats, the number of c-Fos-like immunoreactive neurons were markedly reduced in both the superficial and deep lamina of the dorsal horn. Our findings support the role of DRt as a pain facilitator in acute and chronic pain states, and suggest a key role of glutamate receptors during the development and maintenance of formalin-induced secondary allodynia.

Calcium Imaging and Amperometric Recording in Cultured Chromaffin Cells and Adrenal Slices from Normotensive, Wistar Kyoto Rats and Spontaneously Hypertensive Rats.

The spontaneously hypertensive rat (SHR) is a model widely used to investigate the causal mechanisms of essential hypertension. The enhanced catecholamine (CA) release reported in adrenal glands from adult SHRs raised considerable interest for its possible implication in the genesis of hypertension. The use of powerful techniques such as calcium imaging, electrophysiology, and single-cell amperometry to monitor in real time the key steps in CA secretion has allowed a better understanding of the role of chromaffin cells (CC) in the pathophysiology of hypertension, although several questions remain. Additionally, the implementation of these techniques in preparations in situ, such as the acute adrenal gland slice, which maintains the microenvironment, cell-to-cell communication, and anatomical structure similar to that of the intact adrenal gland, yields data that may have even greater physiological relevance. Here, we describe the procedures to measure the blood pressure of rats in a noninvasive manner, how to obtain primary cultures of adrenal chromaffin cells and acute adrenal slices, and how to perform amperometric recordings and intracellular calcium imaging in these preparations.

Expression of voltage-gated Ca2+ channels, Insp3Rs, and RyRs in the immature mouse ovary.

BACKGROUND: The postnatal mammalian ovary undergoes a series of changes to ensure the maturation of sufficient follicles to support ovulation and fecundation over the reproductive life. It is well known that intracellular [Ca2+]i signals are necessary for ovulation, fertilization, and egg activation. However, we lack detailed knowledge of the molecular identity, cellular distribution, and functional role of Ca2+ channels expressed during folliculogenesis. In the neonatal period, ovarian maturation is controlled by protein growth factors released from the oocyte and granulosa cells. Conversely, during the early infantile period, maturation becomes gonadotropin-dependent and is controlled by granulosa and theca cells. The significance of intracellular Ca2+ signaling in folliculogenesis is supported by the observation that mice lacking the expression of Ca2+/calmodulin-dependent kinase IV in granulosa cells suffer abnormal follicular development and impaired fertility. RESULTS: Using immunofluorescence in frozen ovarian sections and confocal microscopy, we assessed the expression of high-voltage activated Ca2+ channel alpha subunits and InsP3 and ryanodine receptors in the postnatal period from 3 to 16 days. During the neonatal stage, oocytes from primordial and primary follicles show high expression of various Ca2+-selective channels, with granulosa and stroma cells expressing significantly less. These channels are likely involved in supporting Ca2+-dependent secretion of peptide growth factors. In contrast, during the early and late infantile periods, Ca2+ channel expression in the oocyte diminishes, increasing significantly in the granulosa and particularly in immature theca cells surrounding secondary follicles. CONCLUSIONS: The developmental switch of Ca2+ channel expression from the oocytes to the perifollicular cells likely reflects the vanishing role of the oocytes once granulosa and theca cells take control of folliculogenesis in response to gonadotropins acting on their receptors.

Assessing the treatment of cannabidiolic acid methyl ester: a stable synthetic analogue of cannabidiolic acid on c-Fos and NeuN expression in the hypothalamus of rats.

BACKGROUND: Cannabidiol (CBD), the non-psychotropic compound from Cannabis sativa, shows positive results on controlling several health disturbances; however, comparable data regarding additional chemical from C. sativa, such as cannabidiolic acid (CBDA), is scarce due to its instability. To address this limitation, a stable CBDA analogue, CBDA methyl ester (HU-580), was synthetized and showed CBDA-like effects. Recently, we described that HU-580 increased wakefulness and wake-related neurochemicals. OBJECTIVE: To extend the comprehension of HU-580´s properties on waking, the c-Fos and NeuN expression in a wake-linked brain area, the hypothalamus was evaluated. METHODS: c-Fos and NeuN expression in hypothalamic sections were analyzed after the injections of HU-580 (0.1 or 100 µg/kg, i.p.). RESULTS: Systemic administrations of HU-580 increased c-Fos and neuronal nuclei (NeuN) expression in hypothalamic nuclei, including the dorsomedial hypothalamic nucleus dorsal part, dorsomedial hypothalamic nucleus compact part, and dorsomedial hypothalamic nucleus ventral part. CONCLUSION: HU-580 increased c-Fos and NeuN immunoreactivity in hypothalamus nuclei suggesting that this drug might modulate the sleep-wake cycle by engaging the hypothalamus.

Sleep-wake cycle disturbances and NeuN-altered expression in adult rats after cannabidiol treatments during adolescence.

RATIONALE: The medical uses of cannabidiol (CBD), a constituent of the Cannabis sativa, have accelerated the legal and social acceptance for CBD-based medications but has also given the momentum for questioning whether the long-term use of CBD during the early years of life may induce adverse neurobiological effects in adulthood, including sleep disturbances. Given the critical window for neuroplasticity and neuro-functional changes that occur during stages of adolescence, we hypothesized that CBD might influence the sleep-wake cycle in adult rats after their exposure to CBD during the adolescence. OBJECTIVES: Here, we investigated the effects upon behavior and neural activity in adulthood after long-term administrations of CBD in juvenile rats. METHODS: We pre-treated juvenile rats with CBD (5 or 30 mg/Kg, daily) from post-natal day (PND) 30 and during 2 weeks. Following the treatments, the sleep-wake cycle and NeuN expression was analyzed at PND 80. RESULTS: We found that systemic injections of CBD (5 or 30 mg/Kg, i.p.) given to adolescent rats (post-natal day 30) for 14 days increased in adulthood the wakefulness and decreased rapid eye movement sleep during the lights-on period whereas across the lights-off period, wakefulness was diminished and slow wave sleep was enhanced. In addition, we found that adult animals that received CBD during the adolescence displayed disruptions in sleep rebound period after total sleep deprivation. Finally, we determined how the chronic administrations of CBD during the adolescence affected in the adulthood the NeuN expression in the suprachiasmatic nucleus, a sleep-related brain region. CONCLUSIONS: Our findings are relevant for interpreting results of adult rats that were chronically exposed to CBD during the adolescence and provide new insights into how CBD may impact the sleep-wake cycle and neuronal activity during developmental stages.

Exposure to the cannabinoid agonist WIN 55, 212-2 in adolescent rats causes sleep alterations that persist until adulthood.

Cannabis and, to a lesser extent, synthetic cannabinoids are used during adolescence, a period in which multiple brain areas are still undergoing development. Among such areas is the hypothalamus, which is implicated in the control of sleep-wake cycle. In the present report, we show that exposing adolescent rats to the cannabinoid receptor agonist WIN 55, 212-2 (0.1, 0.3 or 1.0 mg/kg, i.p) for 14 days during adolescence (i.e., from post-natal day 30-44) resulted in significant sleep disturbances when the animals became adult (post-natal day 80). These included decreased wakefulness and enhanced rapid eye movement sleep. Furthermore, we found that labeling for NeuN, a marker of postmitotic neurons, was significantly increased the dorsomedial hypothalamic nucleus of rats treated with WIN 55, 212-2. The results suggest that excessive cannabinoid receptor activation during adolescence can persistently influence sleep patterns and neuronal activity later in life.

The retinoid X receptor: a nuclear receptor that modulates the sleep-wake cycle in rats.

RATIONALE: The nuclear receptor retinoid X receptor (RXR) belongs to a nuclear receptor superfamily that modulates diverse functions via homodimerization with itself or several other nuclear receptors, including PPARα. While the activation of PPARα by natural or synthetic agonists regulates the sleep-wake cycle, the role of RXR in the sleep modulation is unknown. OBJECTIVES: We investigated the effects of bexarotene (Bexa, a RXR agonist) or UVI 3003 (UVI, a RXR antagonist) on sleep, sleep homeostasis, levels of neurochemical related to sleep modulation, and c-Fos and NeuN expression. METHODS: The sleep-wake cycle and sleep homeostasis were analyzed after application of Bexa or UVI. Moreover, we also evaluated whether Bexa or UVI could induce effects on dopamine, serotonin, norepinephrine epinephrine, adenosine, and acetylcholine contents, collected from either the nucleus accumbens or basal forebrain. In addition, c-Fos and NeuN expression in the hypothalamus was determined after Bexa or UVI treatments. RESULTS: Systemic application of Bexa (1 mM, i.p.) attenuated slow-wave sleep and rapid eye movement sleep. In addition, Bexa increased the levels of dopamine, serotonin, norepinephrine epinephrine, adenosine, and acetylcholine sampled from either the nucleus accumbens or basal forebrain. Moreover, Bexa blocked the sleep rebound period after total sleep deprivation, increased in the hypothalamus the expression of c-Fos, and decreased NeuN activity. Remarkably, UVI 3003 (1 mM, i.p.) induced opposite effects in sleep, sleep homeostasis, neurochemicals levels, and c-Fos and NeuN activity. CONCLUSIONS: The administration of RXR agonist or antagonist significantly impaired the sleep-wake cycle and exerted effects on the levels of neurochemicals related to sleep modulation. Moreover, Bexa or UVI administration significantly affected c-Fos and NeuN expression in the hypothalamus. Our findings highlight the neurobiological role of RXR on sleep modulation.

Cannabidiol Partially Blocks the Excessive Sleepiness in Hypocretindeficient Rats: Preliminary Data.

BACKGROUND: Excessive daytime sleepiness and cataplexy are among the symptoms of narcolepsy, a sleep disorder caused by the loss of hypocretin/orexin (HCRT/OX) neurons placed into the Hypothalamus (LH). Several treatments for managing narcolepsy include diverse drugs to induce alertness, such as antidepressants, amphetamine, or modafinil, etc. Recent evidence has shown that cannabidiol (CBD), a non-psychotropic derived from Cannabis sativa, shows positive therapeutic effects in neurodegenerative disorders, including Parkinson´s disease. Furthermore, CBD provokes alertness and enhances wake-related neurochemicals in laboratory animals. Thus, it is plausible to hypothesize that excessive somnolence observed in narcolepsy might be blocked by CBD. OBJECTIVE: Here, we determined whether the systemic injection of CBD (5mg/kg, i.p.) would block the excessive sleepiness in a narcoleptic model. METHODS: To test this idea, the neurotoxin hypocretin-2-saporin (HCRT2/SAP) was bilaterally injected into the LH of rats to eliminate HCRT leading to the establishment of narcoleptic-like behavior. Since excessive somnolence in HCRT2/SAP lesioned rats has been observed during the lights-off period, CBD was administered at the beginning of the dark phase. RESULTS: Hourly analysis of sleep data showed that CBD blocked the sleepiness during the lights-off period across 7h post-injection in lesioned rats. CONCLUSION: Taking together, these preliminary findings suggest that CBD might prevent sleepiness in narcolepsy.

The nonpsychoactive Cannabis constituent cannabidiol is a wake-inducing agent.

Cannabidiol (CBD) is a constituent of Cannabis sativa that induces nonpsychotropic effects, and some of its biological actions in sleep have been described by the authors' group. Here, the authors report that when administered 10 or 20 microg/1 microl during the lights-on period directly into either lateral hypothalamus (LH) or dorsal raphe nuclei (DRN), which are wake-inducing brain areas, CBD enhanced wakefulness and decreased slow wave sleep and REM sleep. Furthermore, CBD increased alpha and theta power spectra but diminished delta power spectra. Additionally, CBD increased c-Fos expression in LH or DRN. These findings suggest that this cannabinoid is a wake-inducing compound that presumably activates neurons in LH and DRN.

Promoting of wakefulness by administrations of modafinil into anterior hypothalamus and into the pedunculopontine tegmental nucleus in rats.

We investigated whether administration of MOD in rats during the lights-on period into wake-promoting areas, such as anterior hypothalamus (AH) or into the pedunculopontine tegmental nucleus (PPTg) would enhance waking. Results showed that microinjections of 1 microL of MOD (10, 20, or 30 microg) into both brain areas increased the total time of alertness and decreased sleep. Additionally, MOD-treated rats showed an enhancement in alpha power spectra but delta power spectra was diminished. Finally, c-Fos expression was found increased into either AH or the PPTg. Collectively, these results suggest that MOD induces waking via the activity of two wake-related brain areas such as AH and the PPTg.

The artificial sweetener Splenda intake promotes changes in expression of c-Fos and NeuN in hypothalamus and hippocampus of rats.

BACKGROUND: Obesity is the result of the interaction of multiple variables, including the excessive increase of sugar-sweetened beverages consumption. Diets aimed to treat obesity have suggested the use of artificial sweeteners. However, recent evidence has shown several health deficits after intake of artificial sweeteners, including effects in neuronal activity. Therefore, the influence of artificial sweeteners consumption such as Splenda, on the expression of c-Fos and neuronal nuclear protein (NeuN) in hypothalamus and hippocampus remains to be determined. OBJECTIVES: We investigated the effects on c-Fos or NeuN expression in hypothalamus and hippocampus of Splenda-treated rats. METHODS: Splenda was diluted in water (25, 75 or 250 mg/100 mL) and orally given to rats during 2 weeks ad libitum. Next, animals were sacrificed by decapitation and brains were collected for analysis of c-Fos or NeuN immunoreactivity. RESULTS: Consumption of Splenda provoked an inverted U-shaped dose-effect in c-Fos expression in ventromedial hypothalamic nucleus while similar findings were observed in dentate gyrus of hippocampus. In addition, NeuN immunoreactivity was enhanced in ventromedial hypothalamic nucleus at 25 or 75 mg/100 mL of Splenda intake whereas an opposite effect was observed at 250 mg/100 mL of artificial sweetener consumption. Lastly, NeuN positive neurons were increased in CA2/CA3 fields of hippocampus from Splenda-treated rats (25, 75 or 250 mg/100 mL). CONCLUSION: Consuming Splenda induced effects in neuronal biomarkers expression. To our knowledge, this study is the first description of the impact of intake Splenda on c-Fos and NeuN immunoreactivity in hypothalamus and hippocampus in rats.

Modafinil enhances extracellular levels of dopamine in the nucleus accumbens and increases wakefulness in rats.

Modafinil (MOD) is a wakefulness-promoting drug that improves the alertness levels in narcolepsy; however, the molecular mechanism of action remains to be elucidated. We found that after a single icv injection of MOD (10 microg/5 microl) the extracellular levels of dopamine (DA) and l-DOPA collected from the nucleus accumbens were increased and decreased, respectively. Separately, the icv administration of MOD (10 microg/5 microl) to rats enhanced wakefulness (W) whereas diminished sleep during 4h. Lastly, the alertness induced by MOD was partially antagonized by the sleep-inducing endocannabinoid anandamide (ANA). We conclude that MOD enhances the extracellular levels of DA, promotes W and its effects on sleep are partially blocked by ANA.

Effects of the fatty acid amide hydrolase inhibitor URB597 on the sleep-wake cycle, c-Fos expression and dopamine levels of the rat.

Our group has described previously that the endogenous cannabinoid anandamide induces sleep. The hydrolysis of this lipid involves the activity of the fatty acid amide hydrolase (FAAH), which additionally catalyzes the degradation of the satiety factor oleoylethanolamide and the analgesic-inducing lipid palmitoylethanolamide. It has been demonstrated that the inhibition of the FAAH by URB597 increases levels of anandamide, oleoylethanolamide and palmitoylethanolamide in the brain of rats. In order to determinate the physiological properties of the FAAH inhibition on the sleep modulation, we report the pharmacological effects on the sleep-wake cycle of the rat after i.c.v. administrations of URB597, oleoylethanolamide or palmitoylethanolamide (10, 20 microg/5 microl). Separate unilateral i.c.v. injections of 3 compounds during the lights-on period, increased wakefulness and decreased slow wave (SW) sleep in rats in a dose-dependent fashion. We additionally found out that, compared to controls, c-Fos immunoreactivity in hypothalamus and dorsal raphe nucleus was increased in rats that received URB597, oleoylethanolamide or palmitoylethanolamide (10, 20 microg/5 microl, i.c.v.). Next, we found that after an injection of the compounds, levels of dopamine were increased whereas extracellular levels of levodopa (l-DOPA) were decreased. These findings indicate that that inhibition of the FAAH, via URB597, modulates waking. These effects were mimicked separately by the administration of oleoylethanolamide or palmitoylethanolamide. The alertness induced by the compounds tested here activated wake-promoting brain regions and they also induced the release of dopamine. Our results suggest that FAAH activity as well as two molecules that are catalyzed by this enzyme, oleoylethanolamide and palmitoylethanolamide, participate in the regulation of the waking state. Alternative approaches to treat sleep disorders such as excessive somnolence might consider the use of the URB597, oleoylethanolamide or palmitoylethanolamide since all compounds enhance waking.

An iron-deficient diet during development induces oxidative stress in relation to age and gender in Wistar rats.

Iron is a trace element and a structural part of antioxidant enzymes, and its requirements vary according to age and gender. We hypothesized that iron deficiency (ID) leads to an increase in free radicals which mainly affect the brain, and the severity of damage would therefore be dependent on age and gender. Two groups of Wistar rats were evaluated evolutionarily: 100 rats (50 males; 50 females) with ID diet and 100 rats (50 males; 50 females) with standard diet. Both groups were offspring from mothers who were previously under the same dietary intervention. The ages studied roughly correspond to stages of human development: birth (0 postnatal day "PND" in rats), childhood (21 PND), early adolescence (42 PND), late adolescence (56 PND), and adulthood (70 PND). The following biomarkers in the brain, blood, and liver were analyzed: lipid peroxidation products (LPO), protein carbonyl content and activity of the antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase. It was demonstrated that ID subjects are born with high levels of LPO in the brain and low antioxidant activity, the damage being more severe in males. After birth, antioxidant defense focuses on the central level (brain) in ID females and on the peripheral level (blood and liver) in ID males. In two critical stages of development, birth and late adolescence, antioxidant protection is insufficient to counteract oxidative damage in ID subjects. Moreover, we observed that the variability of results in the literature on oxidative stress and ID comes from gender and age of the subjects under study. With this, we can establish patterns and exact moments to carry out studies or treatments.

Cannabidiol, a constituent of Cannabis sativa, modulates sleep in rats.

Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and cannabidiol (CBD) are two major constituents of Cannabis sativa. Delta(9)-THC modulates sleep, but no clear evidence on the role of CBD is available. In order to determine the effects of CBD on sleep, it was administered intracerebroventricular (icv) in a dose of 10 microg/5 microl at the beginning of either the lights-on or the lights-off period. We found that CBD administered during the lights-on period increased wakefulness (W) and decreased rapid eye movement sleep (REMS). No changes on sleep were observed during the dark phase. Icv injections of CBD (10 microg/5microl) induced an enhancement of c-Fos expression in waking-related brain areas such as hypothalamus and dorsal raphe nucleus (DRD). Microdialysis in unanesthetized rats was carried out to characterize the effects of icv administration of CBD (10 microg/5 microl) on extracellular levels of dopamine (DA) within the nucleus accumbens. CBD induced an increase in DA release. Finally, in order to test if the waking properties of CBD could be blocked by the sleep-inducing endocannabinoid anandamide (ANA), animals received ANA (10 microg/2.5 microl, icv) followed 15 min later by CBD (10 microg/2.5 microl). Results showed that the waking properties of CBD were not blocked by ANA. In conclusion, we found that CBD modulates waking via activation of neurons in the hypothalamus and DRD. Both regions are apparently involved in the generation of alertness. Also, CBD increases DA levels as measured by microdialysis and HPLC procedures. Since CBD induces alertness, it might be of therapeutic value in sleep disorders such as excessive somnolence.