OBJECTIVETo explicate the spinal nerve source of the rabbit penis cutaneous sensation.

METHODSTwelve adult male rabbits were randomly divided into two groups of equal number. While mechanical stimuli were given to the penis by different von Frey hairs, single fiber activities were recorded in vivo in the left (Group A) and right (Group B) S1-S4 spinal nerves, respectively. The mechanical threshold, adaptability and conduction velocity of the fibers were analyzed.

RESULTSWhen the ipsilateral penis was mechanically stimulated, discharges were detected in S2 and S3 spinal nerve fibers, but not in S1 and S4. The discharge fibers were 39.67 +/- 3.14 (S2) and 21.00 +/- 2.19 (S3) in the left spinal nerve and 40.00 +/- 3.16 (S2) and 19.67 +/- 2.58 (S3) in the right. There was no obvious difference between the numbers of the left spinal nerves and the right ones (P > 0.05).

CONCLUSIONThe rabbit penis cutaneous sensation originates from S2 and S3 spinal nerves.

Animals ; Electrophysiology ; Male ; Neurons, Afferent ; physiology ; Penis ; Rabbits ; Random Allocation ; Sensory Thresholds ; Skin ; innervation ; Spinal Nerves ; physiology

Obesity is a prevalent disease with significant morbidity and mortality. It is a state of chronic low-grade inflammation due to excess body fat. Weight homeostasis is maintained through changes in various gastrointestinal hormones caused by dietary intake. However, being overweight or obese breaks the balance of these appetite-related gastrointestinal hormones and creates resistance to the actions of these hormones. The sensitivity of vagal afferent neurons to peripheral signals becomes blunted. Cytokines produced by excessive fat tissue damage our normal immune system, making us vulnerable to infection. In addition, various changes in gastrointestinal motility occur. Therefore, this review focuses on the various changes in gastrointestinal hormones, the immune state, the vagus nerve, and gastrointestinal movement in obese patients.
Adipose Tissue ; Cytokines ; Gastrointestinal Hormones ; Gastrointestinal Motility ; Homeostasis ; Humans ; Immune System ; Inflammation ; Mortality ; Neurons, Afferent ; Obesity ; Overweight ; Physiology ; Vagus Nerve

The excitability of nociceptive neurons increases in the intact dorsal root ganglion (DRG) after a chronic compression, but the underlying mechanisms are still unclear. The aim of this study was to investigate the ionic mechanisms underlying the hyperexcitability of nociceptive neurons in the compressed ganglion. Chronic compression of DRG (CCD) was produced in adult rats by inserting two rods through the intervertebral foramina to compress the L4 DRG and the ipsilateral L5 DRG. After 5-7 d, DRG somata were dissociated and placed in culture for 12-18 h. In sharp electrode recording model, the lower current threshold and the depolarized membrane potential in the acutely dissociated CCD neurons were detected, indicating that hyperexcitability is intrinsic to the soma. Since voltage-gated K(+) (Kv) channels in the primary sensory neurons are important for the regulation of excitability, we hypothesized that CCD would alter K(+) current properties in the primary sensory neurons. We examined the effects of 4-aminopyridine (4-AP), a specific antagonist of A-type potassium channel, on the excitability of the control DRG neurons. With 4-AP in the external solution, the control DRG neurons depolarized (with discharges in some cells) and their current threshold decreased as the CCD neurons demonstrated, indicating the involvement of decreased A-type potassium current in the hyperexcitability of the injured neurons. Furthermore, the alteration of A-type potassium current in nociceptive neurons in the compressed ganglion was investigated with the whole-cell patch-clamp recording model. CCD significantly decreased A-type potassium current density in nociceptive DRG neurons. These data suggest that a reduction in A-type potassium current contributes, at least in part, to the increase in neuron excitability that may lead to the development of pain and hyperalgesia associated with CCD.
Animals ; Female ; Ganglia, Spinal ; physiopathology ; Hyperalgesia ; etiology ; physiopathology ; Neurons, Afferent ; physiology ; Nociceptors ; physiology ; Pain ; physiopathology ; Potassium Channels ; physiology ; Radiculopathy ; physiopathology ; Rats ; Rats, Sprague-Dawley

The sleep-wake cycle displays a characteristic 24-hour periodicity, providing an opportunity to dissect the endogenous circadian clock through the study of aberrant behaviour. This article surveys the properties of circadian clocks, with emphasis on mammals. Information was obtained from searches of peer-reviewed literature in the PUBMED database. Features that are highlighted include the known molecular components of clocks, their entrainment by external time cues and the output pathways used by clocks to regulate metabolism and behaviour. A review of human circadian rhythm sleep disorders follows, including recent discoveries of their genetic basis. The article concludes with a discussion of future approaches to the study of human circadian biology and sleep-wake behaviour.
ARNTL Transcription Factors ; Animals ; Basic Helix-Loop-Helix Transcription Factors ; physiology ; CLOCK Proteins ; Circadian Rhythm ; genetics ; physiology ; Humans ; Neurons, Afferent ; physiology ; Neurons, Efferent ; physiology ; Polymorphism, Single Nucleotide ; Sleep Disorders, Circadian Rhythm ; genetics ; physiopathology ; Suprachiasmatic Nucleus ; cytology ; physiology ; Trans-Activators ; physiology

Sciatic nerve injury is a common disease of peripheral nerve in clinic. After nerve injury, there are many dysfunctions in motoneurons and muscles following regeneration. Previous studies mostly investigated the aspects related to the injured nerve, and the effect on the recurrent inhibition (RI) pathway of spine following regeneration was not fully understood. Following reinnervation after temporary sciatic nerve crush, the functional alteration of RI was studied. In adult rats, RI between lateral gastrocnemius-soleus (LG-S) and medial gastrocnemius (MG) motor pools was assessed by conditioning monosynaptic reflexes (MSRs) elicited from the cut dorsal roots and recorded from either the LG-S or MG nerves by antidromic stimulation of the synergist muscle nerve. The following results were obtained. (1) The RI of MSRs in rats was almost lost (<5 weeks) after sciatic nerve crush. Although the RI partially recovered following reinnervation (6 weeks), it remained permanently depressed (up to 14 weeks). (2) Sciatic nerve crush on one side did not affect the contralateral RI. (3) Sciatic nerve crush did not induce any motoneuron loss revealed by immunohistochemistry. Peripheral nerve temporary disconnection causes long term alterations in RI pathway which make up motoneuron's function enhance for the alteration of muscle power and suggests that peripheral nerve injury induces long term plastic changes in the spinal motoneuron circuitry.
Animals ; Long-Term Synaptic Depression ; physiology ; Male ; Motor Neurons ; physiology ; Nerve Crush ; Nerve Regeneration ; physiology ; Neuronal Plasticity ; physiology ; Neurons, Afferent ; physiology ; Rats ; Rats, Wistar ; Reflex, Monosynaptic ; physiology ; Sciatic Nerve ; injuries ; physiopathology ; Spinal Cord ; physiopathology ; Spinal Nerve Roots ; physiopathology

Veratridine, a blocker of inactive gate of sodium channel, was used to perfuse L5 dorsal root ganglion (DRG) topically. Afferent activities of type A single fiber from these DRGs were recorded. It was found that after a 10-min bath of veratridine (1.8-3 micromol/L), some of the primary silent DRG neurons were triggered by touch or pressure on the receptive fields or by electrical stimulation of the sciatic nerve to produce high-frequency firing, which was termed triggered oscillation presenting a U-type of interspike intervals (ISI) or other types of oscillations. The longer the intervals between stimulating pulses, the more stimulating pulses were needed to trigger the oscillation. The oscillation, triggered by electric stimuli with different duration or patterns, had no significant difference in their patterns. The duration of the inhibitory period after a triggered oscillation was generally 30-90 s. It was also observed that this kind of triggered oscillation was induced by afferent pulses of the same neurons. These results suggest that triggered oscillation, which may contribute to the fit of triggered pain, can be produced in primary sensory neurons after application of veratridine.
Action Potentials ; physiology ; Animals ; Female ; Ganglia, Spinal ; cytology ; drug effects ; Male ; Neurons, Afferent ; physiology ; Rats ; Rats, Sprague-Dawley ; Sodium Channel Blockers ; pharmacology ; Veratridine ; pharmacology

The authors describe here the procedures for using the gelatin half-embedding method to obtain thin spinal cord slices with attached dorsal roots and performing visually guided whole-cell patch-clamp recording of postsynaptic currents evoked by primary afferent fibers in rat spinal dorsal horn. A segment of spinal cord with attached dorsal roots was prepared and half-embedded in an agar block with 20% (w/v) gelatin. Thin spinal cord slices with attached dorsal roots were obtained with a vibratome and whole-cell patch-clamp configuration was established under the infrared observation. At the holding potential of -70 mV, spontaneous excitatory postsynaptic currents (EPSCs) and dorsal root stimulation-evoked EPSCs were recorded as inward currents. According to the conduction velocity of afferent fibers and stimulus threshold, evoked EPSCs that are mediated by A-like or C-like fibers were distinguished. At the holding potential of 0 mV, spontaneous inhibitory postsynaptic currents (IPSCs) and dorsal root stimulation-evoked IPSCs were recorded as outward currents. Using 5 micromol/L strychnine or 20 micromol/L bicuculline, GABAergic or glycinergic evoked IPSCs could be isolated. Using visual patch-clamp method synaptic transmission can be accurately assessed by measuring postsynaptic currents of the dorsal horn neurons. More importantly, with the aid of infrared observation, the incidence of failure to establish a clamp configuration can be greatly reduced and it becomes easier to make recordings from the neurons in deep dorsal horn laminae. Thus, the present research approach an effective approach to study the modulation of primary afferent synaptic transmission.
Animals ; Electrophysiology ; Evoked Potentials ; physiology ; Excitatory Postsynaptic Potentials ; physiology ; Female ; Male ; Neurons, Afferent ; physiology ; Patch-Clamp Techniques ; methods ; Posterior Horn Cells ; physiology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; cytology ; physiology ; Synaptic Transmission ; physiology

AIMTo explore the influence of GABAergic neurotransmitters and GABAA receptors on the auditory afferent impulses recorded in the brainstem evoked by electro-stimulation.

METHODSBrainstem slices were prepared using ddy/ddy mice of postnatal 0-5th days. The brainstem slices were stained with a voltage-sensitive dye(NK3041). The cut end of the vestibulocochlear nerve (nVIIIth) connected with slices was stimulated by a tungsten electrode, a 16 x 16 pixels silicon photodiode array apparatus was used to record the optical mapping from auditory brainstem slices. The data were analyzed by ARGUS-50/PDA software.

RESULTSThe spatial-temporal patterns of the excitatory propagation from the vestibulocochlear nerve (nVIIIth) to cochlear nucleus and vestibular nucleus were displayed with multiple-sites optical recording. The optical signal coming from one pixel consisted of a fast spike-like response and a following slow response. Inhibitory neurotransmitter GABA decreased the fast spike-like response and following slow response of evoked optical signals, while an antagonist BMI against GABAA receptors increased the both responses.

CONCLUSIONA 16 x 16 pixel silicon photodiode array apparatus can be used to record multiple-sites optical mapping evoked by electro-stimulation to the cut end of the vestibulocochlear nerve. The every optical signal consists of both presynaptic and postsynaptic elements. Inhibitory neurotransmitter GABA and an antagonist BMI of GABAA receptors can modulate the excitatory propagation of evoked optical signals.

Animals ; Animals, Newborn ; Auditory Pathways ; physiology ; Brain Stem ; physiology ; Evoked Potentials, Auditory, Brain Stem ; physiology ; In Vitro Techniques ; Mice ; Neurons, Afferent ; physiology ; Optics and Photonics ; Photic Stimulation ; Receptors, GABA-A ; physiology ; gamma-Aminobutyric Acid ; physiology

The modulation by substance P of gamma-aminobutyric acid (GABA)- and 5-hydroxytryptamine (5-HT)-activated currents (I(GABA) and I(5-HT)) was studied by using patch-clamp technique in rat trigeminal ganglion (TG) neurons. The majority of neurons examined responded to GABA and 5-HT with inward currents in the same cells (63.8%, 30/47). In 22 out of 30 neurons sensitive to both GABA and 5-HT, pretreatment with substance P (SP, 0.01 micromol/L) suppressed I(GABA) by (35.7 +/-6.1)% and enhanced I(5-HT) by (65.2 +/- 8.7)%. GR 82334, a potent and specific antagonist of NK1 tachykinin receptor, reversibly blocked the modulatory effects of SP. The SP modulation on I(GABA) and I(5-HT) was also abolished by intracellular dialysis of GDP-beta-S, a non-hydrolyzable GDP analog, or GF 109203X, a selective protein kinase C inhibitor. These results suggest that SP exerts opposite modulatory actions on GABA(A) receptor and 5-HT3 receptor activity of the same primary sensory neuron via the same intracellular signal transduction pathway.
Animals ; Animals, Newborn ; GABA Antagonists ; pharmacology ; Neurons, Afferent ; physiology ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Serotonin ; physiology ; Serotonin Antagonists ; pharmacology ; Substance P ; pharmacology ; physiology ; Trigeminal Ganglion ; physiology ; gamma-Aminobutyric Acid ; physiology

Initially, when periaqueductal gray (PAG) is electrically stimulated, analgesia is induced, and this phenomenon is called stimulation-produced analgesia. Nucleus raphe magnus (NRM) as well as PAG are known to be the potent analgesic centers. NRM could modulate the nociceptive response of spinal cord neurons through spinally projecting fibers. However, as well as the above analgesic effects have been confined to the somatic pain, it was variable according to species, and the analgesic effect by NRM stimulation on the visceral pain was not yet clarified. In this study the analgesic effect by NRM stimulation on the visceral pain was examined through recording the activities of the dorsal horn neurons with renal input and renal pain, as a type of visceral pain. The renal pain was induced by ureteral occlusion or renal arterial occlusion, which in turn activated the renal mechanoreceptor or chemoreceptor. These cells had concomitant somatic input. In order to compare the effects of NRM stimulation on the renal pain with somatic pain, the somatic stimulation such as squeezing was conducted on the peripheral receptive field. The main results are summarized as follows: 1) After an electrical stimulation of NRM, spontaneous activities of dorsal horn neurons with renal input were reduced to 73.3 +/- 9.7% of the control value. 2) After an electrical stimulation of NRM, activities of dorsal horn neurons with renal input evoked by a brush, a type of non-noxious stimuli, did not change significantly. But the activities by a squeeze, a type of noxious stimuli, the activities were reduced to 63.2 +/- 7.2% of the control value. 3) After an electrical stimulation of NRM, activities of dorsal horn neurons with renal input evoked by occlusion of ureter or renal artery were reduced to 46.7 +/- 8.8% and 49.0 +/- 8.0% of the control value respectively. 4) The inhibitory effect of NRM on the dorsal horn neurons with renal input did not show any difference between renal A delta fiber and C fiber group. 5) By the electrical stimulation of NRM, the activities evoked by ureteral occlusion showed more reduction in the high threshold cell group than in the wide dynamic range cell group. These results suggest that activation of NRM can alleviate the renal pain as well as the somatic pain by modulating the dorsal horn neurons activities.
Afferent Pathways/cytology/physiology ; Animal ; Cats ; Electric Stimulation ; Female ; Kidney/innervation/*physiopathology ; Male ; Nervous System/cytology ; Nervous System Physiology ; Neurons/physiology ; *Pain Threshold ; Raphe Nuclei/*physiology ; Spinal Cord/cytology/physiology ; Support, Non-U.S. Gov't