Hippocampal electrophysiological changes during the elicited metabolic syndrome in Wistar rats.

The Metabolic Syndrome (MS) is a set of alterations that increase the risk of developing type 2 diabetes mellitus (DM2). There is evidence that obesity and the development of metabolic syndrome lead to alterations in cognitive processes. In this work it was proposed to determine if generating the metabolic syndrome produces changes in the electric unitary spontaneous activity in the hippocampus as a possible sustain of the learning alterations.

Morphine administration and abrupt cessation alter the behavioral diurnal activity pattern.

In mammals, there is an underlying mechanism that dictates the organism's biological functions and daily activity schedule, known as circadian rhythms, which play a major role in maintaining steady metabolism, homeostasis, and immunity. Limited research has been done investigating the effects of continuous opiate administration on the circadian rhythm activity pattern. A change in circadian activity pattern is suggested as an experimental model to demonstrate long-term effect of the drug.

Interferon modulates central nervous system function.

The interferons (IFNs) are an endogenous pleiotropic family of cytokines that perform fundamental physiological functions as well as protecting host organisms from disease and in maintaining homeostasis. This review covers the effects of endogenous IFN on the nervous system. It starts with the description of its receptors, followed how it modulate neuronal activity, mood, sleep, temperature, the endocrine system, the opioid system and how it regulate food consumption and the immune system.

Melatonin attenuates the decrement of dendritic protein MAP-2 immuno-staining in the hippocampal CA1 and CA3 fields of the aging male rat.

Neuronal death during brain aging results, at least in part, from the disruption of synaptic connectivity caused by oxidative stress. Synaptic elimination might be caused by increased instability of the neuronal processes. In vitro evidence shows that melatonin increases MAP-2 expression, a protein that improves the stability of the dendritic cytoskeleton, opening the possibility that melatonin could prevent synaptic elimination by increasing dendritic stability.

Methylphenidate and amphetamine modulate differently the NMDA and AMPA glutamatergic transmission of dopaminergic neurons in the ventral tegmental area.

Behavioral and neurochemical studies suggest that the induction of behavioral sensitization to psychostimulants involves transient changes at the synapses of the ventral tegmental area's dopaminergic neurons (VTA-DA). Differences in the behavioral response to amphetamine (Amph) and methylphenidate (MPD) were observed. In an attempt to understand these behavioral differences at the neuronal level, the dose-response characteristics of these two psychostimulants on electrophysiologically identified VTA-DA neurons at the glutamatergic synapse were investigated.

Dopaminergic ventral tegmental neurons modulated by methylphenidate.

Treatment of psychostimulants leads to the development of behavioral sensitization, an augmented behavioral response to drug re-administration. The induction of behavioral sensitization to psychostimulants such as amphetamine and cocaine occurs at the ventral tegmental area's dopaminergic neurons (VTA-DA). Currently, there is limited experimental data about the physiological properties of methylphenidate (MPD) on VTA-DA neurons.

Galphimine B modulates synaptic transmission on dopaminergic ventral tegmental area neurons.

Galphimine B (GB) is a bioactive compound isolated from the plant Galphimia glauca Cav. (Malpighiaceae) and has been shown to have central nervous system depressant properties. In an earlier study, it was reported that both systemic and local administration of GB modified the extracellular spontaneous spiking activity in the ventral tegmental area (VTA) neurons.

Apamin blocks the direct relaxant effect of melatonin on rat ileal smooth muscle.

The present study investigated the mechanisms of melatonin-induced inhibition of the ileal smooth muscle contraction. Rat isolated ileal smooth muscle strips were stimulated in an organ bath using carbachol (CAR) or potassium chloride (KCl) depolarization. Under these conditions, melatonin produced a concentration-dependent inhibition of muscle contraction (mean inhibitory concentration, IC50: 17.

Melatonin modulates cholinergic transmission by blocking nicotinic channels in the guinea-pig submucous plexus.

Melatonin, a hormone produced and released by the pineal gland is also synthesized by cells of the gastrointestinal wall, where it might be a local regulator of gut functions. In this study, we investigated the possible role of melatonin as a modulator of the enteric nervous system. Intracellular recordings were made in neurons of the submucosal plexus from the guinea-pig ileum to measure the melatonin effects on their electrophysiological properties.

Interferon modulates neuronal activity recorded from the hypothalamus, thalamus, hippocampus, amygdala and the somatosensory cortex.

Neuromodulators interact with classically defined neurotransmitters to regulate a variety of biological processes. The aim of the present study was to study whether interferon-alpha (IFN) can be considered as a neuromodulator. Single cell recordings from five CNS structures were recorded before and following three different routes of IFN administration in Sprague-Dawley rats to substantiate that IFN is a neuromodulator.

ATP inhibits the synaptic release of acetylcholine in submucosal neurons.

Previously, we have shown that adenosine inhibits release of acetylcholine (ACh) by acting at A1 presynaptic receptors in guinea pig submucosal synapses. In this study, intracellular recordings were made to investigate the actions of ATP and some analogs on the synaptic release of ACh. Superfusion of these substances decreased the amplitude and duration of electrically induced fast excitatory postsynaptic potentials (EP-SPs) in about 90% of the tested neurons.

Alpha-interferon suppresses food intake and neuronal activity of the lateral hypothalamus.

Alpha-interferon (alpha-IFN) treatment in humans induces anorexic effects. However, the mechanisms and sites of action are unknown. Rats implanted with an intracerebroventricular (i.

Melatonin modifies the spontaneous multiunit activity recorded in several brain nuclei of freely behaving rats.

Melatonin, a pineal hormone, released photoperiodically, was administered systemically in rats, previously implanted with semimicroelectrodes into six different brain structures. The multiunit electrical activity of these structures was recorded for 10 min before and 60 min after melatonin administration in unanesthetized, freely moving rats. Different melatonin doses (100, 200, 500, and 1000 micrograms/kg) produced changes in the electrical activity of all tested structures.

Noxious and non-noxious responses in the medial thalamus of the rat.

Single-cell experiments were undertaken to localize and characterize the medial thalamic (MT) neurons which respond to noxious and non-noxious input in the rat. The observations demonstrated that: (1) 61 and 42% of MT neurons respond to noxious (Nox) and non-noxious (NN) stimulation, respectively; (2) MT neurons exhibit 4 cell types according to their pattern of response; Type A units were excited exclusively by Nox stimulation; Type B units were excited exclusively by NN stimulation; Type C units were excited by both (Nox and NN) stimulation, and Type D units exhibited decreases in firing rate following both stimulation modalities; (3) neurons of the parafascicularis nucleus exhibit more noxious responses (Type A units) than other medial thalamic areas.

Dorsal raphe stimulation, 5-HT and morphine microiontophoresis effects on noxious and nonnoxious identified neurons in the medial thalamus of the rat.

In single cell experiments, the characterization of the responses of medial thalamic neurons to noxious and nonnoxious stimulation was made to examine the effects of two substances involved in pain, morphine and 5-HT, and the action of one pain suppressor mechanism, dorsal raphe stimulation. Single cell activity was recorded in urethane anesthetized rats. Tail pinch and tail immersion in hot water were used as nociceptive stimuli.

Rat pineal exhibits two electrophysiological patterns of response to microiontophoretic norepinephrine application.

The spontaneous activity of 117 pineal units was recorded in urethane-anesthetized rats. The pineal units exhibited a wide range of firing rates of which 50% were on average slower than 14 spikes per second. Superior cervical ganglion (SCG) stimulation was studied in 76 pineal units; this stimulation caused excitation in 55% of the units.

Does the immune system communicate with the central nervous system? Interferon modifies central nervous activity.

The present investigation determined whether an immunomodulator agent modified the central nervous system activity as measured behaviorally and neurophysiologically. Two types of interferons (IFNs), alpha (alpha) and gamma (gamma), were applied locally (microiontophoretically) into various regions of the rat brain simultaneously with single neuron recording from the cerebral cortex, hippocampus, thalamus and hypothalamus. Of the various IFNs, only alpha-IFN altered single cell activity in all brain structures in a dose-dependent manner.

Alpha and gamma interferons' effects on cortical and hippocampal neurons: microiontophoretic application and single cell recording.

Responses of 96 extracellular spontaneous active cortical and hippocampal neurons to microiontophoretically applied four types of alpha interferons (alpha-IFNs), one type of gamma interferon (gamma-IFN) as well as three fractions of gamma-IFNs were examined. All four types of alpha-IFN ejections increased the discharge of the majority of neuron tested. Significant differences of the number of cells excited and the intensity of the excitation among the 4 types of alpha-IFN were observed.

Microiontophoretic application of morphine and naloxone to neurons in hypothalamus of rat.

The present experiments used urethane-anesthetized rats and single cell recording to study the electrophysiological properties of ventromedial hypothalamic (VMH) cells following different doses of morphine and naloxone, applied microiontophoretically. More than 45% of ventromedial hypothalamic units reacted in a dose-response fashion to local application of morphine. In the majority of the ventromedial hypothalamic neurons, naloxone failed to reverse the effects of morphine.

Effects of morphine on: spontaneous, dorsal raphe, spinal tract of trigeminal nucleus, medial lemniscus and reticular lateral magnocellular evoked responses of hypothalamic units, in naive and morphine physically dependent rats.

The spontaneous activity and the inputs to the medial basal hypothalamus (MBH) following dorsal raphe (DR), spinal tract of the trigeminal nerve (SpV), medial lemniscus (ML), reticular lateral magnocellular nucleus ( RLM ) and acoustic (Ac) stimulation and the effects of morphine and the opioid antagonist, naloxone, on these inputs, were investigated in morphine-naive and morphine-dependent animals. The observations were obtained in freely behaving animals previously implanted with permanent electrodes. The spontaneous activity of MBH neurons exhibits heterogenic spontaneous firing rates.

Differential effects of interferon on ventromedial hypothalamus and dorsal hippocampus.

Three incremental doses of recombinant alpha-interferon (IF) were applied iontophoretically to hippocampal and hypothalamic cells. IF produced a dose-dependent long-lasting excitation in hippocampal neurons, whereas, in the hypothalamus alpha-IF elicited biphasic responses. The highest IF currents induced changes in the amplitude of the action potentials on both structures.

Novel effects of interferon on the brain: microiontophoretic application and single cell recording in the rat.

Interferon (IF), one of the most controversial drugs in cancer therapy, induces a variety of CNS side effects. Therefore, IF was tested on single neuronal activity and compared with other drugs. Recombinant leukocyte A IF, morphine sulfate and L-glutamate were applied microiontophoretically to 18 cortical and 29 thalamic neurons.