OBJECTIVEA few investigations have been reported about pretectal suppressive influences on the optic tectum of frog, but characteristics of tectal activity to pretectal input are left unknown. We made intracellular recordings to demonstrate the unexpected complexity in synaptic mechanisms involved in the suppressive influences of pretecal stimulation on the tectal cells.

METHODSIn the present study, we investigated the neuronal activity evoked by pretectal (Lpd/P) nuclei stimulation using intracellular recording technique.

RESULTSThe pretectal stimulation mainly elicited two types of responses in the ipsilateral tectum: an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP) and a pure IPSP. The latter predominated in the tectal cells responding to pretectal stimulation. In a few cells, biphasic hyperpolarization appeared under stronger stimulus intensities. The spikes of tecto-pretectal projecting cells elicited by antidromical stimulation were recorded in the ipsilateral tectum, which revealed reciprocal connections between the tectum and particular pretectal nuclei. The synaptic natures underlying pretecto-tectal information transformation have also been demonstrated. EPSPs with short latencies were concluded to be monosynaptic. Most IPSPs were generated through polysynaptic paths, but monosynaptic IPSPs were also recorded in the tectum. Nearly 98% of impaled tectal cells (except for antidromically projecting cells) showed inhibitory responses to pretectal stimulation.

CONCLUSIONThe results provide strong evidence that pretectal cells broadly inhibit tectal neurons as that has suggested by behavioral and extracellular recording studies.

Animals ; Electric Stimulation ; Excitatory Postsynaptic Potentials ; physiology ; Female ; Inhibitory Postsynaptic Potentials ; physiology ; Male ; Neural Inhibition ; physiology ; Neural Pathways ; cytology ; physiology ; Neurons ; physiology ; Rana catesbeiana ; physiology ; Superior Colliculi ; cytology ; physiology

In the present study, the responses of inhibitory gustatory neurons in the parabrachial nucleus (PBN) to four basic taste stimuli NaCl, HCl, quinine HCl (QHCl) and sucrose were examined using single-unit recording technique in anesthetized rats. A total of 18 inhibitory taste neurons in the PBN were obtained. Spontaneous firing rates of these inhibitory neurons were 0.2-5.5 Hz with mean firing rate of (2.15+/-0.31) Hz. Most of the neurons responded to more than one of the basic taste qualities. The inhibitory responses to taste occurred quickly and lasted 5-80 s in different PBN neurons. According to the responsive characteristics to the four basic taste stimuli, the neurons could be classified as NaCl-best (n=8), HCl-best (n=3), QHCl-best (n=3), and sucrose-best (n=4). The breadth of tuning of NaCl-best neurons was the highest (0.945). Inhibitory responsive neurons had feeble discrimination among sapid stimuli or aversive stimuli. These results suggest that there exist inhibitory taste neurons in the PBN. These neurons may play some useful roles in precise transmission of taste information and the taste coding for hedonic and aversive tastes.
Animals ; Male ; Neural Inhibition ; physiology ; Neurons ; physiology ; Pons ; physiology ; Rats ; Rats, Sprague-Dawley ; Taste ; physiology

OBJECTIVETo investigate the masseter inhibitory reflex (MIR) and its eventual changes in patients with episodic tension-type headache (TTH).

METHODSMIR was studied in 21 patients with episodic TTH and 30 healthy subjects, with age and sex matched to the study cohort. Median age of patients was 17.0 years (ranged 16~49 years), median duration of disease 12 months (1~5 years), and median frequency of headache 7.5 d per month.

RESULTSThe second period of suppression (S2) of MIR was reduced in intensity and duration in 10% of controls and 66.7% (confidence interval (CI)=45.3%~85%; P<0.05) of patients with episodic TTH (chi(2)=74.9; P<0.001). In 3 (14.3%) of patients with episodic TTH, S2 was completely absent. No significant correlation between the duration of disease and headache frequency was found.

CONCLUSIONOur results confirm the link between episodic TTH and reduction or absence of S2. Teenage patients with episodic TTH may exhibit marked pathological changes in S2 in contrast to older individuals.

Adolescent ; Adult ; Cluster Headache ; physiopathology ; Female ; Humans ; Male ; Masseter Muscle ; physiopathology ; Middle Aged ; Neural Inhibition ; Reflex ; Tension-Type Headache ; physiopathology ; Young Adult

Animals choose among sleep, courtship, and feeding behaviors based on the integration of both external sensory cues and internal states; such choices are essential for survival and reproduction. These competing behaviors are closely related and controlled by distinct neural circuits, but whether they are also regulated by shared neural nodes is unclear. Here, we investigated how a set of male-specific P1 neurons controls sleep, courtship, and feeding behaviors in Drosophila males. We found that mild activation of P1 neurons was sufficient to affect sleep, but not courtship or feeding, while stronger activation of P1 neurons labeled by four out of five independent drivers induced courtship, but only the driver that targeted the largest number of P1 neurons affected feeding. These results reveal a common neural node that affects sleep, courtship, and feeding in a threshold-dependent manner, and provide insights into how competing behaviors can be regulated by a shared neural node.
Animals ; Animals, Genetically Modified ; Brain ; cytology ; Courtship ; Drosophila ; Drosophila Proteins ; genetics ; metabolism ; Feeding Behavior ; physiology ; Locomotion ; Male ; Neural Inhibition ; physiology ; Neural Pathways ; physiology ; Neurons ; physiology ; Sex Factors ; Sleep ; physiology

OBJECTIVEThe literature has shown that cognitive and emotional changes may occur after chronic treatment with glucocorticoids. This might be caused by the suppressive effect of glucocorticoids on hippocampal neurogenesis and cell proliferation. Paroxetine, a selective serotonin reuptake transporter, is a commonly used antidepressant for alleviation of signs and symptoms of clinical depression. It was discovered to promote hippocampal neurogenesis in the past few years and we wanted to investigate its interaction with glucocorticoid in this study.

METHODSAdult rats were given vehicle, corticosterone, paroxetine, or both corticosterone and paroxetine for 14 d. Cell proliferation in the dentate gyrus was quantified using 5-bromo-2-deoxyuridine (BrdU) immunohistochemistry.

RESULTSThe corticosterone treatment suppressed while paroxetine treatment increased hippocampal cell proliferation. More importantly, paroxetine treatment could reverse the suppressive effect of corticosterone on hippocampal cell proliferation.

CONCLUSIONThis may have clinic application in preventing hippocampal damage after glucocorticoid treatment.

Analysis of Variance ; Animals ; Bromodeoxyuridine ; metabolism ; Cell Count ; Cell Proliferation ; drug effects ; Corticosterone ; pharmacology ; Drug Interactions ; Hippocampus ; cytology ; Male ; Neural Inhibition ; drug effects ; Neurons ; drug effects ; Paroxetine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Serotonin Uptake Inhibitors ; pharmacology

gamma -aminobutyric acid (GABA) is an inhibitory neurotransmitter in adult mammalian central nervous system (CNS). During CNS development, the role of GABA is switched from an excitatory transmitter to an inhibitory transmitter, which is caused by an inhibition of calcium influx into postsynaptic neuron derived from release of GABA. The switch is influenced by the neuronal chloride concentration. When the neuronal chloride concentration is at a high level, GABA acts as an excitatory neurotransmitter. When neuronal chloride concentration decreases to some degree, GABA acts as an inhibitory neurotransmitter. The neuronal chloride concentration is increased by Na+-K+-Cl(-)-Cl(-) cotransporters 1 (NKCC1), and decreased by K+-Cl(-) cotransporter 2 (KCC2).
Animals ; Calcium Signaling ; physiology ; Cell Differentiation ; physiology ; Central Nervous System ; cytology ; embryology ; metabolism ; Chlorides ; metabolism ; Humans ; Neural Inhibition ; physiology ; Neurons ; cytology ; metabolism ; Synapses ; metabolism ; Synaptic Transmission ; physiology ; gamma-Aminobutyric Acid ; metabolism ; physiology

Stimulation of the trigeminal nerve can elicit various cardiovascular and autonomic responses; however, the effects of anesthesia with pentobarbital sodium on these responses are unclear. Pentobarbital sodium was infused intravenously at a nominal rate and the lingual nerve was electrically stimulated at each infusion rate. Increases in systolic blood pressure (SBP) and heart rate (HR) were evoked by lingual nerve stimulation at an infusion rate between 5 and 7 mg·kg(-1)·h(-1). This response was associated with an increase in the low-frequency band of SBP variability (SBP-LF). As the infusion rate increased to 10 mg·kg(-1)·h(-1) or more, decreases in SBP and HR were observed. This response was associated with the reduction of SBP-LF. In conclusion, lingual nerve stimulation has both sympathomimetic and sympathoinhibitory effects, depending on the depth of pentobarbital anesthesia. The reaction pattern seems to be closely related to the autonomic balance produced by pentobarbital anesthesia.
Adjuvants, Anesthesia ; administration & dosage ; pharmacology ; Adrenergic alpha-Antagonists ; pharmacology ; Animals ; Autonomic Nervous System ; drug effects ; Cats ; Dose-Response Relationship, Drug ; Electric Stimulation ; Electrocardiography ; drug effects ; Hemodynamics ; drug effects ; Hexamethonium ; pharmacology ; Hypnotics and Sedatives ; administration & dosage ; pharmacology ; Infusions, Intravenous ; Lingual Nerve ; drug effects ; physiology ; Male ; Neural Inhibition ; Phentolamine ; pharmacology ; Trigeminal Nerve ; drug effects ; physiology

OBJECTIVEOur previous work suggested that sensitivity of hippocampal neurons is changed in process of epileptic activities, and closely parallel to the dynamic characteristic of epileptic activity of the neurons. This study investigated the sensitivity of epileptic brain to vagal nerve stimulation (VNS) in epileptic process.

METHODSEpileptic model was evoked by penicillin. Left vagal nerves were stimulated to inhibit the seizures induced by penicillin. The electrocorticography (ECoG) and electromyography (EMG) were recorded to analyze inhibiting effect of VNS in epileptic process.

RESULTSIt was found that VNS could inhibit the seizures caused by penicillin, and the inhibiting effect of VNS to seizures increased as the vagal nerve stimulating time prolonged. It was also found that the inhibiting effect of VNS to seizures decreased in epileptic process.

CONCLUSIONThe results suggested that the sensitivity of epileptic brain to VNS was different in epileptic process. The inhibiting effect of VNS to seizure decreased as the development of seizures.

Action Potentials ; physiology ; Animals ; Electric Stimulation ; Electroencephalography ; Electromyography ; Epilepsy ; chemically induced ; prevention & control ; Frontal Lobe ; physiopathology ; Male ; Motor Cortex ; drug effects ; physiopathology ; Neural Inhibition ; physiology ; Nonlinear Dynamics ; Parietal Lobe ; physiopathology ; Penicillins ; Rats ; Rats, Sprague-Dawley ; Seizures ; chemically induced ; prevention & control ; Vagus Nerve ; physiology

OBJECTIVETo study the central role of ginkgolide B (BN52021) in regulating cardiovascular function of nerve center by examining the effects of ginkgolide B on the electrical activity of rat paraventricular nucleus (PVN) neurons in hypothalamic slice preparation and to elucidate the mechanism involved.

METHODSExtracellular single-unit discharge recording technique.

RESULTS(1) In response to the application of ginkgolide B (0.1, 1, 10 micromol/L; n = 27) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 26 (26/27, 96.30%) neurons were significantly decreased in a dose-dependent manner. (2) Pretreatment with L-glutamate (L-Glu, 0.2 mmol/L) led to a marked increase in the SDR of all 8 (100%) neurons in an epileptiform pattern. The increased discharges were suppressed significantly after ginkgolide B (1 micromol/L) was applied into the perfusate for 2 min. (3) In 8 neurons, perfusion of the selective L-type calcium channel agonist, Bay K 8644 (0.1 micromol/L), induced a significant increase in the discharge rates of 8 (8/8, 100%) neurons, while ginkgolide B (1 micromol/L) applied into the perfusate, could inhibit the discharges of 8 (100%) neurons. (4) In 8 neurons, the broad potassium channels blocker, tetraethylammonium (TEA, 1 mmol/L) completely blocked the inhibitory effect of ginkgolide B (1 micromol/L).

CONCLUSIONThese results suggest that ginkgolide B can inhibit the electrical activity of paraventricular neurons. The inhibitory effect may be related to the blockade of L-type voltage-activated calcium channel and potentially concerned with delayed rectifier potassium channel (K(DR)).

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester ; pharmacology ; Action Potentials ; drug effects ; Analysis of Variance ; Animals ; Animals, Newborn ; Calcium Channel Agonists ; pharmacology ; Dose-Response Relationship, Drug ; Drug Interactions ; Fibrinolytic Agents ; pharmacology ; Ginkgolides ; pharmacology ; Glutamic Acid ; pharmacology ; In Vitro Techniques ; Lactones ; pharmacology ; Neural Inhibition ; drug effects ; Neurons ; drug effects ; Paraventricular Hypothalamic Nucleus ; cytology ; Potassium Channel Blockers ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Tetraethylammonium ; pharmacology

It has been reported that the frequency modulation (FM) or FM direction sensitivity and forward masking of central auditory neurons are related with the neural inhibition, but there are some arguments, because no direct evidence of inhibitory synaptic input was obtained in previous studies using extracellular recording. In the present study, we studied the relation between FM direction sensitivity and forward masking of the inferior collicular (IC) neurons using in vivo intracellular recordings in 20 Mus musculus Km mice. Thirty seven with complete data among 93 neurons were analyzed and discussed. There was an inhibitory area which consisted of inhibitory postsynaptic potentials (IPSP) at high frequency side of frequency tuning of up-sweep FM (FMU) sensitive neurons (n = 12) and at low frequency side of frequency tuning of down-sweep FM (FMD) selective neurons (n = 8), while there was no any inhibitory area at both sides of frequency tuning of non-FM sweep direction (FMN) sensitive neurons (n = 17). Therefore, these results show that the inhibitory area at low or high frequency side of frequency tuning is one of the mechanisms for forming FM sweep direction sensitivity of IC neurons. By comparison of forward masking produced by FMU and FMD sound stimuli in FMU, FMD and FMN neurons, the selective FM sounds could produce stronger forward masking than the non-selective in FMU and FMD neurons, while there was no forward masking difference between FMU and FMD stimuli in the FMN neurons. We suggest that the post-action potential IPSP is a potential mechanism for producing stronger forward masking in FMU and FMD neurons.
Acoustic Stimulation ; Action Potentials ; Animals ; Inferior Colliculi ; cytology ; Inhibitory Postsynaptic Potentials ; Mice ; Neurons ; cytology