Action potential firing rhythms in the suprachiasmatic nucleus of the diurnal grass rat, Arvicanthis niloticus.

In mammals, daily physiological activities are regulated by a central circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Recently, an increasing number of studies have used diurnal grass rats to analyze neuronal mechanisms regulating diurnal behavior. However, spontaneous action potential firing rhythms in SCN neurons have not been demonstrated clearly in diurnal grass rats.

A candidate gene of Alzheimer diseases was mutated in senescence-accelerated mouse prone (SAMP) 8 mice.

The senescence-accelerated mouse prone (SAMP) 8 strain exhibits age-related learning and memory deficits (LMD) at 2 months of age. We have found strong association of chromosome 12 locus with learning memory deficit (LMD) phenotype in SAMP8 strain. In the course of searching candidate gene, here we identified solute carrier family 24 sodium/potassium/calcium exchanger member 4 (Slc24a4) in SAMP8 chromosome 12 LMD possessing one single nucleotide polymorphism causing amino acid replacement of Threonine at 413 position with Methionine.

Canonical versus non-canonical transsynaptic signaling of neuroligin 3 tunes development of sociality in mice.

Neuroligin 3 (NLGN3) and neurexins (NRXNs) constitute a canonical transsynaptic cell-adhesion pair, which has been implicated in autism. In autism spectrum disorder (ASD) development of sociality can be impaired. However, the molecular mechanism underlying NLGN3-mediated social development is unclear.

Intracellular interplay between cholecystokinin and leptin signalling for satiety control in rats.

Cholecystokinin (CCK) and leptin are satiety-controlling peptides, yet their interactive roles remain unclear. Here, we addressed this issue using in vitro and in vivo models. In rat C6 glioma cells, leptin pre-treatment enhanced Ca mobilization by a CCK agonist (CCK-8s).

Posttetanic enhancement of striato-pallidal synaptic transmission.

The striato (Str)-globus pallidus external segment (GPe) projection plays major roles in the control of neuronal activity in the basal ganglia under both normal and pathological conditions. The present study used rat brain slice preparations to characterize the enhancement of Str-GPe synapses observed after repetitive conditioning stimuli (CS) of Str with the whole cell patch-clamp recording technique. The results show that 1) the Str-GPe synapses have a posttetanic enhancement (PTE) mechanism, which is considered to be a combination of an augmentation and a posttetanic potentiation; 2) the degree of PTE observed in GPe neurons had a wide range and was positively correlated with a wide range of paired-pulse ratios assessed before application of CS; 3) a wide range of CS, from frequencies as low as 2 Hz with as few as 5 pulses to as high as 100 Hz with 100 pulses, could induce PTE; 4) the decay time constant of PTE was dependent on the strength of CS and was prolonged greatly, up to 120 s, when strong CS were applied; and 5) the level of postsynaptic Cl(-) became a limiting factor for the degree of PTE when strong CS were applied.

Serotonin-2C receptor involved serotonin-induced Ca²⁺ mobilisations in neuronal progenitors and neurons in rat suprachiasmatic nucleus.

The hypothalamic suprachiasmatic nucleus (SCN), the central circadian pacemaker in mammals, undergoes serotonergic regulation, but the underlying mechanisms remain obscure. Here, we generated a subclone of an SCN progenitor cell line expressing Ca(2+) sensors (SCN2.2YC) and compared its 5-HT receptor signalling with that of rat SCN neurons in brain slices.

Possible involvement of Hcn1 ion channel in learning and memory dysfunction in SAMP8 mice.

The senescence-accelerated mouse prone 8 (SAMP8) strain exhibits age-related learning and memory deficits (LMD) at 2 months of age. Combined linkage analysis of 264 F2 intercross SAMP8 × JF1 mice and RNA-seq analysis identified Hcn1 gene out of 29 genes in the LMD region on chromosome 13. Hcn1 in SAMP8 strain showed 15 times less polyglutamine repetition compared to Japanese fancy mouse 1 (JF1).

Development of an image processing support system based on fluorescent dye to prevent elderly people with dementia from wandering.

The wandering of elderly people with dementia is a significant behavioral problem and is a heavy burden on caregivers in residential and nursing homes. Thus, warning systems have been developed to prevent elderly people with dementia from leaving the premises. Some of these systems use radio waves.

Short-term plasticity shapes activity pattern-dependent striato-pallidal synaptic transmission.

The cortico-striato (Str)-globus pallidus external segment (GPe) projection plays major roles in the control of neuronal activity in the basal ganglia under both normal and pathological conditions. The present study used rat brain-slice preparations to address our hypothesis that the gain of this disynaptic projection is dynamically controlled by activations of short-term plasticity mechanisms of Str-GPe synapses. The Str-GPe projection neurons fire with very different frequency and firing patterns in vivo depending on the condition of the animal.

Ghrelin postsynaptically depolarizes dorsal raphe neurons in rats in vitro.

Ghrelin promotes growth hormone (GH) secretion and feeding. Recent studies further showed that ghrelin displayed a defending effect against the depressive-like symptoms and affected sleep in animals and humans. Serotonergic system is considered to be implicated in feeding, depression and other mood disorders, and sleep.

Electrophysiological effects of orexin-B and dopamine on rat nucleus accumbens shell neurons in vitro.

Orexin (ORX) plays a critical role in reward-seeking behavior for natural rewards and drugs of abuse. The mesolimbic dopamine (DA) pathway that projects into the nucleus accumbens (NAc) from the ventral tegmental area is deeply involved in the neural mechanisms underlying reward, drug abuse and motivation. A recent study demonstrated that ORX-immunopositive fibers densely project into the shell of the NAc (NAcSh), suggesting that the NAcSh might be a site of the interaction between the ORXergic and DAergic systems for reward-seeking behavior.

Cytosolic calcium elevation induced by orexin/hypocretin in granule cell domain cells of the rat cochlear nucleus in vitro.

Using rat brain slice preparations, we examined the effect of orexin on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) in the granule cell domain (GCD) cells of the cochlear nucleus that carry non-auditory information to the dorsal cochlear nucleus. Application of orexin concentration-dependently increased [Ca(2+)](i), and in two thirds of GCD cells these increases persisted in the presence of tetrodotoxin. There was no significant difference between the dose-response curve for orexin-A and that for orexin-B.

Electrophysiological effect of ghrelin and somatostatin on rat hypothalamic arcuate neurons in vitro.

Growth hormone (GH) secretion from the pituitary gland is partly regulated by GH releasing hormone (GHRH)-containing neurons located in the hypothalamic arcuate nucleus (ARC). GHRH-containing neurons express the GH secretagogue (GHS) receptor (GHS-R) and the somatostatin (SRIF) receptor. Recently, an endogenous ligand for the GHS-R named ghrelin was found.

Microinjection of neuropeptide S into the rat ventral tegmental area induces hyperactivity and increases extracellular levels of dopamine metabolites in the nucleus accumbens shell.

The newly identified neuropeptide S (NPS) is mainly expressed in a group of neurons located between the locus coeruleus and Barrington's nucleus in the brainstem. Central administration of NPS increases motor activity and wakefulness, and it decreases anxiety-like behavior and feeding. The NPS receptor (NPSR) is widely distributed in various brain regions including the ventral tegmental area (VTA).

Electrophysiological effects of neuropeptide S on rat ventromedial hypothalamic neurons in vitro.

The newly identified neuropeptide S (NPS) is a ligand for a previously orphan G protein-coupled GPR 154 receptor, now named the NPS receptor (NPSR). Previous studies have shown that NPS induces hyperlocomotion, increases arousal and suppresses anxiety-like behaviors via NPSR. Although NPS also inhibits food intake, nothing is known about the neuronal mechanisms underlying this action.

Electrophysiological effects of ghrelin on laterodorsal tegmental neurons in rats: an in vitro study.

Ghrelin, a gut and brain peptide, is a potent stimulant for growth hormone (GH) secretion and feeding. Recent studies further show a critical role of ghrelin in the regulation of sleep-wakefulness. Laterodorsal tegmental nucleus (LDT), that regulates waking and rapid eye movement (REM) sleep, expresses GH secretagogue receptors (GHS-Rs).

Orexin-A and ghrelin depolarize the same pedunculopontine tegmental neurons in rats: an in vitro study.

Orexin (ORX), also called hypocretin, and ghrelin are newly identified peptides in the brain and/or peripheral organs, and they are involved in the regulation of sleep-wakefulness as well as feeding. In our previous studies we have found that ORX and ghrelin each depolarizes more than half of the cholinergic neurons recorded in the pedunculopontine tegmental nucleus (PPT) via a dual ionic mechanism including a decrease of K(+) conductance and an increase of nonselective cationic conductance. Thus, the present study was carried out to investigate whether ORX-A and ghrelin both depolarize the same PPT neuron.

Electrophysiological effects of orexin/hypocretin on nucleus accumbens shell neurons in rats: an in vitro study.

Orexin-A (ORX-A) and orexin-B (ORX-B) play critical roles in the regulation of sleep-wakefulness, energy homeostasis, neuroendocrine system and autonomic functions. Although ORXs are also implicated in the reward process, their electrophysiological effects on neurons in the shell of nucleus accumbems (NAcSh) have not been described thoroughly. Therefore we examined the electrophysiological effects of ORXs on rat NAcSh neurons.

Electrophysiological effects of ghrelin on pedunculopontine tegmental neurons in rats: An in vitro study.

Ghrelin is a potent stimulant for growth hormone (GH) secretion and feeding. Recent studies further show a critical role of ghrelin in the regulation of sleep-wakefulness. Pedunculopontine tegmental nucleus (PPT), which regulates waking and rapid eye movement (REM) sleep, expresses GH secretagogue receptors (GHS-Rs).

Electrophysiological effects of orexins/hypocretins on pedunculopontine tegmental neurons in rats: an in vitro study.

Orexin-A (ORX-A) and orexin-B (ORX-B) play critical roles in the regulation of sleep-wakefulness and feeding. ORX neurons project to the pedunculopontine tegmental nucleus (PPT), which regulates waking and rapid eye movement (REM) sleep. Thus, we examined electrophysiological effects of ORXs on rat PPT neurons with a soma size of more than 30 microm.

Effects of ghrelin on neuronal activity in the ventromedial nucleus of the hypothalamus in infantile rats: an in vitro study.

Ghrelin is an endogenous ligand for the growth hormone (GH) secretagogue (GHS) receptor (GHS-R) and a potent stimulant for GH secretion even in infantile rats before puberty. Although the ventromedial nucleus of the hypothalamus (VMH) might be a site of action for ghrelin to induce GH release, the electrophysiological effect of ghrelin on VMH neurons in infantile rats remains to be elucidated. Thus, the purpose of the present study was to investigate the effect of ghrelin on VMH neurons using hypothalamic slices of infantile rats.