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1.
J Neurosci Res ; 102(8): e25373, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39101281

ABSTRACT

The master control of mammalian circadian rhythms is the suprachiasmatic nucleus (SCN), which is formed by the ventral and dorsal regions. In SCN neurons, GABA has an important function and even excitatory actions in adulthood. However, the physiological role of this neurotransmitter in the developing SCN is unknown. Here, we recorded GABAergic postsynaptic currents (in the perforated-patch configuration using gramicidin) to determine the chloride reversal potential (ECl) and also assessed the immunological expression of the Na-K-Cl cotransporter 1 (NKCC1) at early ages of the rat (postnatal days (P) 3 to 25), during the day and night, in the two SCN regions. We detected that ECl greatly varied with age and depending on the SCN region and time of day. Broadly speaking, ECl was more hyperpolarized with age, except for the oldest age studied (P20-25) in both day and night in the ventral SCN, where it was less negative. Likewise, ECl was more hyperpolarized in the dorsal SCN both during the day and at night; while ECl was more negative at night both in the ventral and the dorsal SCN. Moreover, the total NKCC1 fluorescent expression was higher during the day than at night. These results imply that NKCC1 regulates the circadian and developmental fluctuations in the [Cl-]i to fine-tune ECl, which is crucial for either excitatory or inhibitory GABAergic actions to occur in the SCN.


Subject(s)
Chlorides , Circadian Rhythm , Solute Carrier Family 12, Member 2 , Suprachiasmatic Nucleus , Animals , Suprachiasmatic Nucleus/metabolism , Circadian Rhythm/physiology , Rats , Solute Carrier Family 12, Member 2/metabolism , Male , Chlorides/metabolism , gamma-Aminobutyric Acid/metabolism , Rats, Wistar , Patch-Clamp Techniques , Aging/physiology
2.
J Neurosci Res ; 99(9): 2287-2304, 2021 09.
Article in English | MEDLINE | ID: mdl-34061383

ABSTRACT

The episodes of cerebral dysfunction, known as encephalopathy, are usually coincident with liver failure. The primary metabolic marker of liver diseases is the increase in blood ammonium, which promotes neuronal damage. In the present project, we used an experimental model of hepatic encephalopathy in male rats by portacaval anastomosis (PCA) surgery. Sham rats had a false operation. After 13 weeks of surgery, the most distinctive finding was vacuolar/spongiform neurodegeneration exclusively in the molecular layer of the cerebellum. This cerebellar damage was further characterized by metabolic, histopathological, and behavioral approaches. The results were as follows: (a) Cellular alterations, namely loss of Purkinje cells, morphological changes, such as swelling of astrocytes and Bergmann glia, and activation of microglia; (b) Cytotoxic edema, shown by an increase in aquaporin-4 and N-acetylaspartate and a reduction in taurine and choline-derivate osmolytes; (c) Metabolic adjustments, noted by the elevation of circulating ammonium, enhanced presence of glutamine synthetase, and increase in glutamine and creatine/phosphocreatine; (d) Inflammasome activation, detected by the elevation of the marker NLRP3 and microglial activation; (e) Locomotor deficits in PCA rats as assessed by the Rotarod and open field tests. These results lead us to suggest that metabolic disturbances associated with PCA can generate the cerebellar damage that is similar to morphophysiological modifications observed in amyloidogenic disorders. In conclusion, we have characterized a distinctive cerebellar multi-disruption accompanied by high levels of ammonium and associated with spongiform neurodegeneration in a model of hepatic hypofunctioning.


Subject(s)
Cerebellum/metabolism , Cerebellum/pathology , Hepatic Encephalopathy/metabolism , Hepatic Encephalopathy/pathology , Locomotion/physiology , Portacaval Shunt, Surgical/trends , Animals , Astrocytes/metabolism , Astrocytes/pathology , Cerebellum/surgery , Hepatic Encephalopathy/surgery , Male , Microglia/metabolism , Microglia/pathology , Neurons/metabolism , Neurons/pathology , Purkinje Cells/metabolism , Purkinje Cells/pathology , Rats , Rats, Wistar
3.
Front Neurosci ; 15: 604165, 2021.
Article in English | MEDLINE | ID: mdl-33679297

ABSTRACT

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairment in communication and social interaction, repetitive or stereotypical behaviors, altered sensory perception, and sleep disorders. In general, the causes of ASD remain unknown, but in Phelan-McDermid syndrome, it is known that the disorder is related to the haploinsufficiency of the Shank3 gene. We used an autism model with compromised glutamatergic signaling, the Shank3+/- mouse, to study the circadian rhythm architecture of locomotion behavior and its entrainment to light. We also analyzed the synapse between the retinohypothalamic tract (RHT) and the suprachiasmatic nucleus (SCN), employing tract tracing and immunohistochemical techniques. We found that Shank3+/- mice were not impaired in the SCN circadian clock, as indicated by a lack of differences between groups in the circadian architecture in entrained animals to either long or short photoperiods. Circadian rhythm periodicity (tau) was unaltered between genotypes in constant darkness (DD, dim red light). Similar results were obtained in the re-entrainment to shifts in the light-dark cycle and in the entrainment to a skeleton photoperiod from DD. However, Shank3+/- mice showed larger phase responses to light pulses, both delays and advances, and rhythm disorganization induced by constant bright light. Immunohistochemical analyses indicated no differences in the RHT projection to the SCN or the number of SCN neurons expressing the N-methyl-D-aspartate (NMDA) receptor subunit NR2A, whereas the Shank3+/- animals showed decreased c-Fos induction by brief light pulses at CT14, but increased number of vasoactive intestinal polypeptide (VIP)-positive neurons. These results indicate alterations in light sensitivity in Shank3+/- mice. Further studies are necessary to understand the mechanisms involved in such increased light sensitivity, probably involving VIP neurons.

4.
Eur J Neurosci ; 51(1): 429-453, 2020 01.
Article in English | MEDLINE | ID: mdl-30408249

ABSTRACT

Adult rabbits show robust circadian rhythms of: nursing, food and water intake, hard faeces excretion, locomotion, body temperature, blood and intraocular pressure, corticosteroid secretion, and sleep. Control of several circadian rhythms involves a light-entrained circadian clock and a food-entrained oscillator. Nursing periodicity, however, relies on a suckling stimulation threshold. Brain structures regulating this activity include the paraventricular nucleus and preoptic area, as determined by lesions and quantification of cFOS- and PER1 clock gene-immunoreactive proteins. Melatonin synthesis in the rabbit pineal gland shows a diurnal rhythm, with highest values at night and lowest ones during the day. In kits the main zeitgeber is milk intake, which synchronizes locomotor activity, body temperature, and corticosterone secretion. Brain regions involved in these effects include the median preoptic nucleus and several olfactory structures. As models for particular human illnesses rabbits have been valuable for studying glaucoma and cardiovascular disease. Circadian variations in intraocular pressure (main risk factor for glaucoma) have been found, with highest values at night, which depend on sympathetic innervation. Rabbits fed a high fat diet develop cholesterol plaques and high blood pressure, as do humans, and such increased fat intake directly modulates cardiovascular homeostasis and circadian patterns, independently of white adipose tissue accumulation. Rabbits have also been useful to investigate the characteristics of sleep across the day and its modulation by infections, cytokines and other endogenous humoral factors. Rabbit circadian biology warrants deeper investigation of the role of the suprachiasmatic nucleus in regulating most behavioral and physiological rhythms described above.


Subject(s)
Circadian Clocks , Suprachiasmatic Nucleus , Animals , Biology , CLOCK Proteins , Circadian Rhythm , Female , Male , Rabbits
5.
J Biol Rhythms ; 34(1): 39-50, 2019 02.
Article in English | MEDLINE | ID: mdl-30654688

ABSTRACT

The suprachiasmatic nucleus (SCN) is the main brain clock that regulates circadian rhythms in mammals. The SCN synchronizes to the LD cycle through the retinohypothalamic tract (RHT), which projects to ventral SCN neurons via glutamatergic synapses. Released glutamate activates N-methyl-D-aspartate (NMDA) receptors, which play a critical role in the activation of signaling cascades to enable phase shifts. Previous evidence indicates that presynaptic changes during postnatal development consist of an increase in RHT fibers impinging on SCN neurons between postnatal day (P) 1 to 4 and P15. The aim of this study was to evaluate postsynaptic developmental changes in the NR2 subunits that determine the pharmacological and biophysical properties of the neuronal NMDA receptors in the ventral SCN. To identify the expression of NR2 subtypes, we utilized RT-PCR, immunohistochemical fluorescence, and electrophysiological recordings of synaptic activity. We identified development-dependent changes in NR2A, C, and D subtypes in mRNA and protein expression, whereas NR2B protein was equally present at all analyzed postnatal ages. The NR2A antagonist PEAQX (100 nM) reduced the frequency of NMDA excitatory postsynaptic currents (EPSCs) at P8 significantly more than at P34, but the antagonists for NR2B (3 µM Ro 25-6981) and NR2C/D (150 nM PPDA) did not influence NMDA EPSCs differently at the 2 analyzed postnatal ages. Our results point to P8 as the earliest analyzed postnatal age that shows mRNA and protein expression similar to those found at the juvenile stage P34. Taken together, our findings indicate that postsynaptic development-dependent modifications in the NR2 subtypes of the NMDA receptor could be important for the synchronization of ventral SCN neurons to the LD cycle at adult stages.


Subject(s)
Aging , Circadian Rhythm , Receptors, N-Methyl-D-Aspartate/physiology , Suprachiasmatic Nucleus Neurons/physiology , Animals , Brain/physiology , Rats , Rats, Wistar , Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors , Synapses/physiology
6.
Chronobiol Int ; 35(12): 1680-1688, 2018 11.
Article in English | MEDLINE | ID: mdl-30095282

ABSTRACT

Eating behavior is controlled by the energy needs of the organism. The need to provide a constant supply of energy to tissues is a homeostatic drive that adjusts feeding behavior to the energetic condition of the organism. On the other hand, food intake also shows a circadian variation synchronized to the light-dark cycle and food availability. Thus, feeding is subjected to both homeostatic and circadian regulation mechanisms that determine the amount and timing of spontaneous food intake in normal conditions. In the present study we contrasted the influence of the homeostatic versus the chronostatic mechanisms on food intake in normal conditions and in response to fasting. A group of rats was subjected to food deprivation under two different temporal schemes. A constant-length 24-h food deprivation started at different times of day resulted in an increased compensatory intake. This compensatory response showed a circadian variation that resembled the rhythm of intake in non-deprived animals. When subjected to fasting periods of increasing length (24-66 h), the amount of compensatory feeding varied according to the time of day in which food was made available, being significantly less when the fast ended in the middle of the light phase or beginning of the dark phase. These oscillatory changes did not have a correlation with variations in the level of glucose or ß-hydroxybutyrate in the blood. The results suggest that the mechanism of homeostatic compensation is modulated chronostatically, presumably as part of the alternation of catabolic and anabolic states matching the daily cycles of activity.


Subject(s)
Eating/physiology , Fasting/physiology , Feeding Behavior/physiology , Homeostasis/physiology , Animals , Circadian Rhythm/physiology , Energy Intake/physiology , Food Deprivation , Male , Photoperiod , Rats, Wistar
7.
Psychopharmacology (Berl) ; 235(4): 1015-1027, 2018 04.
Article in English | MEDLINE | ID: mdl-29306965

ABSTRACT

RATIONALE: The amygdala plays a paramount role in the modulation of anxiety and numerous studies have shown that arginine vasopressin (AVP) elicits anxiogenic effects following either its systemic or septal administration. OBJECTIVES: The aim of this paper was to study the involvement of vasopressinergic neurotransmission in the amygdaloid modulation of unconditioned anxiety and to ascertain whether or not AVP receptor subtypes may have a differential role in this modulation. METHODS: Anxiety behavior was evaluated both in Shock-Probe Burying Test and Light-Dark Box following the bilateral microinfusion of AVP alone or AVP together with either AVP 1a or AVP 1b receptor antagonists into the central amygdala (CeA). RESULTS: AVP microinfusion elicited at low (1 ng/side) but not at high doses (10 ng/side) anxiogenic-like responses in the Shock-Probe Burying Test but not in the Light-Dark Box. SSR149415, an AVP 1b antagonist unlike Manning compound, an AVP 1a antagonist, fully prevented AVP effects in the Shock-Probe Burying Test when it was administered simultaneously with AVP. In addition, oxytocin receptor blockade also failed to affect AVP effects. No effects of any AVP antagonist by itself were observed in both anxiety paradigms. CONCLUSIONS: Our results indicate that AVP 1b receptor contribute to the amygdaloid modulation of anxiety at least in the context of the Shock-Probe Burying Test since no effects were noticed in the Light-Dark Box. It remains to the future to ascertain whether AVP receptor subtypes have indeed differential actions either in the modulation of global or specific features of unconditioned anxiety.


Subject(s)
Amygdala/drug effects , Amygdala/metabolism , Anxiety/metabolism , Arginine Vasopressin/administration & dosage , Receptors, Vasopressin/metabolism , Animals , Antidiuretic Hormone Receptor Antagonists/administration & dosage , Anxiety/chemically induced , Anxiety/drug therapy , Hormone Antagonists/administration & dosage , Male , Microinjections , Rats , Rats, Wistar , Receptors, Vasopressin/agonists
8.
Cell Mol Neurobiol ; 38(4): 841-859, 2018 May.
Article in English | MEDLINE | ID: mdl-29110208

ABSTRACT

Growth arrest-specific 1 (Gas1) is a pleiotropic protein that induces apoptosis of tumor cells and has important roles during development. Recently, the presence of two forms of Gas1 was reported: one attached to the cell membrane by a GPI anchor; and a soluble extracellular form shed by cells. Previously, we showed that Gas1 is expressed in different areas of the adult mouse CNS. Here, we report the levels of Gas1 mRNA protein in different regions and analyzed its expressions in glutamatergic, GABAergic, and dopaminergic neurons. We found that Gas1 is expressed in GABAergic and glutamatergic neurons in the Purkinje-molecular layer of the cerebellum, hippocampus, thalamus, and fastigial nucleus, as well as in dopaminergic neurons of the substantia nigra. In all cases, Gas1 was found in the cell bodies, but not in the neuropil. The Purkinje and the molecular layers show the highest levels of Gas1, whereas the granule cell layer has low levels. Moreover, we detected the expression and release of Gas1 from primary cultures of Purkinje cells and from hippocampal neurons as well as from neuronal cell lines, but not from cerebellar granular cells. In addition, using SH-SY5Y cells differentiated with retinoic acid as a neuronal model, we found that extracellular Gas1 promotes neurite outgrowth, increases the levels of tyrosine hydroxylase, and stimulates the inhibition of GSK3ß. These findings demonstrate that Gas1 is expressed and released by neurons and promotes differentiation, suggesting an important role for Gas1 in cellular signaling in the CNS.


Subject(s)
Brain/metabolism , Cell Cycle Proteins/metabolism , Cell Differentiation/physiology , Neurons/metabolism , Animals , Dopaminergic Neurons/metabolism , GPI-Linked Proteins/metabolism , Glutamic Acid/metabolism , Male , Mice , Substantia Nigra/metabolism , Tyrosine 3-Monooxygenase/metabolism , gamma-Aminobutyric Acid/metabolism
9.
Behav Brain Res ; 313: 293-301, 2016 10 15.
Article in English | MEDLINE | ID: mdl-27374159

ABSTRACT

Epidemiological surveys have indicated that anxiety disorders are more frequent in diabetic patients than in the general population. Similar results have been shown in animal studies using the streptozotocin (STZ)-induced diabetes model. The mechanisms underlying this relationship are not clearly understood, but it has been suggested that alterations in the dopaminergic neurotransmission, which plays an important role in the amygdaloid modulation of fear and anxiety, may be involved. The aim of this study was to ascertain whether or not the amygdaloid DA D1 receptors are involved in the increase of anxiety-like behavior observed in "diabetic" animals. Adult Wistar male rats were injected with STZ (50mg/kg, i.p.) in two consecutive days and subjected to the Shock-Probe Burying Test 10days after the beginning of treatment. STZ-treated rats showed a significant increase in immobility/freezing behavior whereas no effects were elicited in latency to bury, burying behavior itself and the number of shocks received during testing as compared with non-diabetic controls. These results suggest the triggering of a passive coping response in the STZ-treated rats. Interestingly, immobility/freezing behavior was reversed following the intra-amygdaloid dopamine D1 receptor blockade by the local microinfusion of SCH23390 (100ng/side). Autoradiographic experiments showed a selective increase of [(3)H]-SCH23390 binding in the ventral intercalated paracapsular islands of STZ-treated rats when compared to the non-treated control group. Our results suggest that a hyperdopaminergic state involving DA D1 receptors within the amygdala may have a role in the increase of anxiety observed in diabetic rats.


Subject(s)
Amygdala/metabolism , Anxiety/metabolism , Receptors, Dopamine D1/metabolism , Amygdala/drug effects , Animals , Anxiety/chemically induced , Anxiety Disorders/drug therapy , Anxiety Disorders/metabolism , Benzazepines/pharmacology , Fear/drug effects , Fear/physiology , Male , Rats, Wistar , Streptozocin , Synaptic Transmission/drug effects
10.
Int. j. morphol ; 32(2): 409-414, jun. 2014. ilus
Article in Spanish | LILACS | ID: lil-714283

ABSTRACT

El núcleo supraquiasmático (NSQ) es el principal reloj biológico de los mamíferos y sincroniza la actividad de la glándula pineal al ciclo luz-oscuridad a través de una vía polisináptica. El efecto de asa de retroalimentación neuroendocrina se lleva a cabo por la melatonina. El presente trabajo pretende demostrar que la glándula pineal modula la sensibilidad a la luz en el NSQ. Se utilizaron ratas Wistar, y se asignaron a 3 grupos: grupo A (falsa pinealectomía -sham-, sin luz), grupo B (falsa pinealectomía -sham- + luz) y grupo C al cual se le realizó la pinealectomía + luz, después de la manipulación se sacrifican para realizar inmunohistoquímica para c-Fos y al final conteo celular por técnica de estereología. Se obtuvo una reducción del 46,8% del promedio de células inmunorreactivas a c-Fos en el grupo C en comparación del grupo B. Este trabajo muestra que la sensibilidad a la luz está modulada por la actividad de la glándula pineal.


The suprachiasmatic nucleus (SCN) is the main and major biological clock in mammals and is responsible for the synchronization of the pineal gland to the light/darkness cycle through a polysynaptic pathway. The neuroendocrine feedback loop effect is carried out by melatonin. This study was carried out to demonstrate that the pineal gland adjusts the sensibility to light in the suprachiasmatic nucleus. Wistar rats were allocated in 3 groups: Group A (sham pinalectomy, without light), group B (sham pinealectomy + light) and group C which underwent real pinalectomy + light. After the intervention the animals were slain to perform immunohistochemistry for c-Fos and cell counting by stereology technique. A 46.8% average reduction in c-Fos immunoreactive cells was achieved in-group C as compared with group B. The present work shows that sensibility to the light is modulate by the activity of the pineal gland.


Subject(s)
Animals , Rats , Pineal Gland/metabolism , Suprachiasmatic Nucleus/metabolism , Biological Clocks , Endocrine Glands/surgery , Circadian Rhythm , Proto-Oncogene Proteins c-fos , Rats, Wistar , Epithalamus/surgery , Melatonin/metabolism
11.
Pharmacol Biochem Behav ; 107: 29-35, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23584096

ABSTRACT

Since the pioneering work of Gadea-Ciria (Gadea-Ciria M, Stadler H, Lloyd KG, Bartholini G. Acetylcholine release within the cat striatum during the sleep-wakefulness cycle. Nature 1973; 243:518-519) indicating pointing to the involvement of acetylcholine and basal ganglia in sleep regulation; extensive literature has suggested that this brain complex participates in the control of the sleep-waking cycle (SWC). On the other hand, it has been demonstrated that the endocannabinoid system (eCBS) is prominently involved in the regulation of the SWC, mood and its related disorders. Since cannabinoid receptor 1 (CB1R) is highly expressed in basal ganglia, in particular in the entopeduncular nucleus (EP), we believe that it is important to know what the role of the EP CB1R is on SWC, depression, and anxiety. To provide insight into the role of the EP CB1R in the regulation of wakefulness (W), non-rapid eye movement sleep (NREMs) and rapid eye movement sleep (REMs), rats were recorded for 24h immediately after a single intra-EP administration of N-arachidonoylethanolamine (AEA) or 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl)pyrazole-3-carboxamide (AM251; CB1 inverse agonist). Likewise, the effect of these drugs on anxiety and depression was tested by means of the elevated plus maze (EPM) and forced swim test (FST), respectively. Results demonstrate that AEA increases NREMs expression, while AM251 increases W and decreases both NREMs and REMs. In addition, administration of AM251 decreases the time rats spent in the open arms and increases immobility time in the FST. It seems that activation of the CB1R in the EP is important to induce sleep, while its blockade promotes W, as well as anxiety and depression, somewhat resembling insomnia in humans. These results suggest that the EP CB1R is modulating sleep and mood.


Subject(s)
Affect/physiology , Endocannabinoids/physiology , Entopeduncular Nucleus/physiology , Sleep/physiology , Wakefulness/physiology , Affect/drug effects , Animals , Arachidonic Acids , Cannabinoid Receptor Agonists/administration & dosage , Cannabinoid Receptor Agonists/pharmacology , Endocannabinoids/administration & dosage , Endocannabinoids/pharmacology , Entopeduncular Nucleus/drug effects , Immobility Response, Tonic/drug effects , Male , Maze Learning/drug effects , Microinjections , Piperidines/administration & dosage , Piperidines/pharmacology , Polyunsaturated Alkamides , Pyrazoles/administration & dosage , Pyrazoles/pharmacology , Rats , Receptor, Cannabinoid, CB1/antagonists & inhibitors , Receptor, Cannabinoid, CB1/physiology , Rotarod Performance Test , Sleep/drug effects , Sleep Stages/drug effects , Wakefulness/drug effects
12.
Brain Res Bull ; 91: 31-7, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23291357

ABSTRACT

Alcohol use disorder is a compulsive behavior driven by motivational systems and by a poor control of consummatory behavior. The entopeduncular nucleus (EP) seems to be involved in the regulation of executive mechanisms, hence, in the expression of behavior. Endocannabinoids (eCB) are involved in alcohol intake mechanisms. The eCB receptor name cannabinoid receptor 1 (CB1R) is expressed in the EP in GABAergic terminals. The role of the eCB system (eCBs) of the EP in the modulation of alcohol seeking and intake behavior is unknown. Therefore, we decided to investigate the role of the eCBs and its interaction with GABA transmission in rat EP, in the regulation of alcohol intake behavior. Rats were submitted to a 10-day period of moderate alcohol (10% in tap water) ingestion. No tap water was available. On day 11, either anandamide (AEA, CB1 receptor agonist), AM251 (CB1R inverse agonist), baclofen (BAC, GABAB receptor agonist), or CGP35348 (GABAB receptor antagonist) was administered into the EP. One bottle of water and one of alcohol (10% in water) were available ad libitum for the following 24 h, and consumption was quantified at the end of this period. Results show that administration of AEA into the EP decreased alcohol consumption while AM251 and BAC administered independently increased alcohol consumption. AEA prevented the increase induced by AM251 or BAC. Likewise, CGP35348 prevented alcohol ingestion induced by AM251. These data suggest that eCBs dysfunction in the EP may be playing a crucial role in the abuse and dependence of alcohol and other drugs.


Subject(s)
Alcohol Drinking/metabolism , Alcoholism/metabolism , Endocannabinoids/metabolism , Entopeduncular Nucleus/metabolism , gamma-Aminobutyric Acid/metabolism , Animals , Entopeduncular Nucleus/drug effects , GABA Agonists/administration & dosage , GABA Antagonists/administration & dosage , Injections, Intraventricular , Male , Rats , Rats, Wistar , Receptor, Cannabinoid, CB1/metabolism , Synaptic Transmission/drug effects , Synaptic Transmission/physiology
13.
J Biol Rhythms ; 24(3): 203-10, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19465697

ABSTRACT

Electrophysiological and calcium mobilization experiments have suggested that the intracellular calcium release channel ryanodine receptors (RyRs) are involved in the circadian rhythmicity of the suprachiasmatic nucleus (SCN). In the present report the authors provide behavioral evidence that RyRs play a specific and major role in the output of the molecular circadian clock in SCN neurons. They measured the circadian rhythm of drinking and locomotor behaviors in dim red light before, during, and after administration of an activator (ryanodine 0.1 microM) or an inhibitor (ryanodine 100 microM) of the RyRs. Drugs were delivered directly into the SCN by cannulas connected to osmotic minipumps. Control treatments included administration of artificial cerebrospinal fluid, KCl (20 mM), tetrodotoxin (1 microM), and anysomicin (5 microg/microl). Activation of RyRs induced a significant shortening of the endogenous period, whereas inhibition of these Ca2+ release channels disrupted the circadian rhythmicity. After the pharmacological treatments the period of rhythmicity returned to basal values and the phase of activity onset was predicted from a line projected from the activity onset of basal recordings. These results indicate that changes in overt rhythms induced by both doses of ryanodine did not involve an alteration in the clock mechanism. The authors conclude that circadian modulation of RyRs is a key element of the output pathway from the molecular circadian clock in SCN neurons in rats.


Subject(s)
Behavior, Animal/physiology , Biological Clocks/physiology , Circadian Rhythm/physiology , Ryanodine Receptor Calcium Release Channel/metabolism , Suprachiasmatic Nucleus/cytology , Animals , Behavior, Animal/drug effects , Biological Clocks/drug effects , Circadian Rhythm/drug effects , Male , Rats , Rats, Wistar , Ryanodine/pharmacology , Suprachiasmatic Nucleus/drug effects
14.
Eur J Neurosci ; 26(3): 575-82, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17686038

ABSTRACT

Ryanodine-sensitive intracellular Ca2+ channels (RyRs) are present in suprachiasmatic nuclei (SCN) neurons, but the functions served by these channels are not known. Here we addressed whether mobilization of intracellular Ca2+ stores through the RyRs may be a link between the molecular clock and the firing rate in SCN neurons. Activation of the RyRs by administration of either 1 mM caffeine or 100 nM ryanodine increased the firing frequency, whereas inhibition of RyRs by 10 microM dantrolene or 80 microm ryanodine decreased firing rate. Similar results were obtained in experiments conducted at either midday or midnight. Furthermore, these effects were not mediated by synaptic transmission as blockade of GABA A, AMPA and NMDA receptors did not prevent the excitatory or inhibitory effects induced by either dose of ryanodine on SCN firing. We conclude that gating of RyRs is a key element of the intricate output pathway from the circadian clock within SCN neurons in rats.


Subject(s)
Biological Clocks/physiology , Calcium Signaling/physiology , Circadian Rhythm/physiology , Neurons/metabolism , Ryanodine Receptor Calcium Release Channel/metabolism , Suprachiasmatic Nucleus/metabolism , Action Potentials/drug effects , Action Potentials/physiology , Animals , Biological Clocks/drug effects , Caffeine/pharmacology , Calcium Signaling/drug effects , Circadian Rhythm/drug effects , Dantrolene/pharmacology , Ion Channel Gating/drug effects , Ion Channel Gating/physiology , Male , Muscle Relaxants, Central/pharmacology , Neurons/drug effects , Patch-Clamp Techniques , Phosphodiesterase Inhibitors/pharmacology , Rats , Rats, Wistar , Receptors, GABA-A/drug effects , Receptors, GABA-A/metabolism , Receptors, Glutamate/drug effects , Receptors, Glutamate/metabolism , Ryanodine/pharmacology , Ryanodine Receptor Calcium Release Channel/drug effects , Suprachiasmatic Nucleus/drug effects , Synaptic Transmission/drug effects , Synaptic Transmission/physiology
15.
Am J Physiol Regul Integr Comp Physiol ; 286(1): R158-65, 2004 Jan.
Article in English | MEDLINE | ID: mdl-12933360

ABSTRACT

The present study aimed to identify the hypothalamic nuclei involved with food entrainment by using c-Fos-like immunoreactivity (c-Fos-IR) as a marker of functional activation. We studied rats entrained 3 wk to restricted feeding schedules (RF), their ad libitum (AL) controls, and the persistence of c-Fos-IR temporal patterns in entrained-fasted rats. In addition, we included 22-h fasting and 22-h fasting-refeeding groups as controls of fasting and refeeding acute effects. Diurnal patterns of c-Fos-IR were observed in the tuberomammilar nucleus (TM) and suprachiasmatic nucleus (SCN) in AL rats. In all nuclei, except the SCN and ventromedial nucleus (VMH), restricted feeding schedules imposed a temporal pattern of increased c-Fos-IR around mealtime. An increase in c-Fos-IR before and after meal time was observed in dorsomedial nucleus (DMH), lateral nucleus (LH), perifornical area (PeF), and TM, and a marked increase was observed in the paraventricular nucleus (PVN) after feeding. Food-entrained c-Fos-IR patterns persisted after 3 days in fasting in DMH, LH, and PeF. Present data suggest that FEO might not rely on a single nucleus and rather may be a distributed system constituted of interacting nuclei in which the PVN is mainly involved with the response to signals elicited by food ingestion and, therefore, with the entraining pathway. We can suggest that the PeF and TM may be involved with the arousal state during food anticipation and the DMH and LH with the time-keeping mechanism of FEO or its output.


Subject(s)
Feeding Behavior/physiology , Hypothalamus/metabolism , Proto-Oncogene Proteins c-fos/metabolism , Animal Feed , Animals , Circadian Rhythm , Fasting/physiology , Immunohistochemistry , Male , Rats , Rats, Wistar , Tissue Distribution
16.
Psiquiatr. biol ; Psiquiatr. biol;9(1): 31-37, mar. 2001. graf
Article in English | LILACS | ID: lil-298981

ABSTRACT

Comparaçä0 dos efeitos terapeuticos e secundarios do haloperidol administrado em doses repartidas no dia contra os efeitos da dose noturna. Em observaçöes clínicas preliminares se encontrou que a hora do dia em que os medicamentos antipsicóticos säo administrados parece que atua na severidade dos efeitos secundários, o que sugere a participaçäo de algum mecanismo circadiano. Para determinar se a hora da administraçäo dos medicamentos aantipsicóticos determina a produçäo dos efeitos tanto terapêuticos com colaterais, comparam-se os efeitos produzidos pela administraçäo do haloperidol em doses distribuidas no dia, contra os efeitos produzidos pela administraçäo em doses noturnas. A avaliaçäo de evoluçäo antipsicotica dos pacientes esquizofrenicos hospitalizados, se realizou mediante a escala dos sintomas positivos e negativos(PANSS). Näo se encontraram diferenças no efeito terapeutico do haloperidol administrado em doses repartidas ou noturnas, em quanto à sub-escala dos sintomas negativos (F(4,87) = 1.709, p = 0,1731) nem dos sintomas gerais (F(4,870 = 2.01, p=0.1187)


Subject(s)
Humans , Adult , Middle Aged , Hypnotics and Sedatives/administration & dosage , Hypnotics and Sedatives/adverse effects , Hypnotics and Sedatives/pharmacology , Schizophrenia , Circadian Rhythm , Dopamine , Basal Ganglia/pathology
17.
Acta psiquiátr. psicol. Am. Lat ; 38(3): 229-36, sept. 1992.
Article in Spanish | LILACS | ID: lil-121985

ABSTRACT

Si se utilizan las funciones mentales que se revisan en el examen del estado mental de los pacientes psiquiátricos y sí se los agrupa en áreas, de acuerdo con criterios fisiológicos clásicos, se obtiene un sistema de manejo de información de valor heurístico en la clínica psiquiátrica. Este sistema considera las funciones mentales del área sensoperceptual como la parte receptora de la inofrmación por el sistema. Tal información continúa su análisis en las áreas cognitiva y afectiva; la salida principal de la información resultante del análisis ocurre a través del área psicomotriz. Este sistema permite elaborar una estructura teórica que correlaciona elementos de las neurociencias con aspectos clínicos psiquiátricos. Por otra parte, permite entender los trastornos mentales como trastornos del manejo de información en el tejido nervioso


Subject(s)
Humans , Mental Processes/physiology , Models, Neurological , Affect/physiology , Cognition/physiology , Nerve Net/physiology , Psychomotor Performance/physiology
18.
Acta psiquiátr. psicol. Am. Lat ; 38(3): 229-36, sept. 1992.
Article in Spanish | BINACIS | ID: bin-25725

ABSTRACT

Si se utilizan las funciones mentales que se revisan en el examen del estado mental de los pacientes psiquiátricos y sí se los agrupa en áreas, de acuerdo con criterios fisiológicos clásicos, se obtiene un sistema de manejo de información de valor heurístico en la clínica psiquiátrica. Este sistema considera las funciones mentales del área sensoperceptual como la parte receptora de la inofrmación por el sistema. Tal información continúa su análisis en las áreas cognitiva y afectiva; la salida principal de la información resultante del análisis ocurre a través del área psicomotriz. Este sistema permite elaborar una estructura teórica que correlaciona elementos de las neurociencias con aspectos clínicos psiquiátricos. Por otra parte, permite entender los trastornos mentales como trastornos del manejo de información en el tejido nervioso (AU)


Subject(s)
Humans , Models, Neurological , Mental Processes/physiology , Nerve Net/physiology , Cognition/physiology , Affect/physiology , Psychomotor Performance/physiology
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