The mesencephalic-hypoglossal nuclei loop as a possible central pattern generator for rhythmical whisking in rats.

It has been previously demonstrated that the Me5 nucleus is involved in the genesis of reflex activities at whisker pad level. Specific Me5 neurons, which provide sensory innervation of the macrovibrissae, are monosynaptically connected with small hypoglossal neurons innervating the extrinsic muscles that control macrovibrissal movements. Artificial whisking, induced by the electrical stimulation of the peripheral stump of the facial nerve and the electrical stimulation of the XII nucleus or the infraorbital nerve, induced evoked responses in the whisker pad extrinsic motor units, along with a significant increase in the electromyographic activity of the extrinsic pad muscles (Mameli et al.

Neurons within the trigeminal mesencephalic nucleus encode for the kinematic parameters of the whisker pad macrovibrissae.

It has been recently shown in rats that spontaneous movements of whisker pad macrovibrissae elicited evoked responses in the trigeminal mesencephalic nucleus (Me5). In the present study, electrophysiological and neuroanatomical experiments were performed in anesthetized rats to evaluate whether, besides the whisker displacement per se, the Me5 neurons are also involved in encoding the kinematic properties of macrovibrissae movements, and also whether, as reported for the trigeminal ganglion, even within the Me5 nucleus exists a neuroanatomical representation of the whisker pad macrovibrissae. Extracellular electrical activity of single Me5 neurons was recorded before, during, and after mechanical deflection of the ipsilateral whisker pad macrovibrissae in different directions, and with different velocities and amplitudes.

Evidence for a trigeminal mesencephalic-hypoglossal nuclei loop involved in controlling vibrissae movements in the rat.

Previous studies performed in rats showed that the whisker-pad motor innervation involves not only the facial nerve, but also some hypoglossal neurons whose axons travel within the trigeminal infraorbital nerve (ION) and target the extrinsic muscles surrounding the whisker-pad macrovibrissae. Furthermore, the electrical stimulation of the ION induced an increase in the EMG activity of these muscles, while the hypoglossal nucleus stimulation elicited evoked potentials and single motor unit responses. However, the existence of a neural network able to involve the XIIth nucleus in macrovibrissae whisking control was totally unknown until now.

Involvement of trigeminal mesencephalic nucleus in kinetic encoding of whisker movements.

In previous experiments performed on anaesthetised rats, we demonstrated that whisking neurons responsive to spontaneous movement of the macrovibrissae are located within the trigeminal mesencephalic nucleus (Me5) and that retrograde tracers injected into the mystacial pad of the rat muzzle extensively labelled a number of Me5 neurons. In order to evaluate the electrophysiological characteristics of the Me5-whisker pad neural connection, the present study analysed the Me5 neurons responses to artificial whisking induced by electrical stimulation of the peripheral stump of the facial nerve. Furthermore, an anterograde tracer was injected into the Me5 to identify and localise the peripheral terminals of these neurons in the mystacial structures.

[Novel fitness techniques: patient selection and cardiovascular impact].

The main objective of this study was to evaluate a number of metabolic and cardiovascular variables during a standard 50 min class performed by spinning bike instructors of both sexes: 6 males and 6 females. Mean power output, heart rate, and oxygen uptake during the performance were 120 ± 4 W, 136 ± 13 bpm, and 32.8 ± 5.

Cytochrome P450 17α-hydroxylase/C(17,20)-lyase immunoreactivity and molecular expression in the cerebellar nuclei of adult male rats.

Several probes have been developed to identify steroidogenic activity in the brain of vertebrates. However, the presence of the cytochrome P450 17α-hydroxylase/C(17,20)-lyase (P450C(17)), an enzyme that converts pregnenolone and progesterone into dehydroepiandrosterone and androstenedione, in specific areas of the cerebellum such as the deep cerebellar nuclei, remains virtually unexplored. Using Western blot analysis and immunohistochemistry, we found molecular expression of P450C(17) in the lateral, interposed and medial deep cerebellar nuclei.

Ischemic preconditioning of the muscle improves maximal exercise performance but not maximal oxygen uptake in humans.

Brief episodes of nonlethal ischemia, commonly known as "ischemic preconditioning" (IP), are protective against cell injury induced by infarction. Moreover, muscle IP has been found capable of improving exercise performance. The aim of the study was the comparison of standard exercise performances carried out in normal conditions with those carried out following IP, achieved by brief muscle ischemia at rest (RIP) and after exercise (EIP).

Role of the trigeminal mesencephalic nucleus in rat whisker pad proprioception.

Background: Trigeminal proprioception related to rodent macrovibrissae movements is believed to involve skin receptors on the whisker pad because pad muscles operate without muscle spindles. This study was aimed to investigate in rats whether the trigeminal mesencephalic nucleus (TMnu), which provides proprioceptive feedback for chewing muscles, may be also involved in whisker pad proprioception.

Methods: Two retrograde tracers, Dil and True Blue Chloride, were injected into the mystacial pad and the masseter muscle on the same side of deeply anesthetized rats to label the respective projecting sensory neurons.

Estimating stroke volume from oxygen pulse during exercise.

This investigation aimed at verifying whether it was possible to reliably assess stroke volume (SV) during exercise from oxygen pulse (OP) and from a model of arterio-venous oxygen difference (a-vO(2)D) estimation. The model was tested in 15 amateur male cyclists performing an exercise test on a cycle-ergometer consisting of a linear increase of workload up to exhaustion. Starting from the analysis of previous published data, we constructed a model of a-vO(2)D estimation (a-vO(2)D(est)) which predicted that the a-vO(2)D at rest was 30% of the total arterial O(2) content (CaO(2)) and that it increased linearly during exercise reaching a value of 80% of CaO(2) at the peak workload (W(max)) of cycle exercise.

Acute variations in homocysteine levels are related to creatine changes induced by physical activity.

Background & Aims: Although many studies have focused on the effects of the physical activity on plasma homocysteine (Hcy) levels, the data gathered up to now are contradictory. In fact, it is true that some researches highlighted an exercise-induced fall in Hcy concentrations, but there are many reports proving that the physical exercise does not contribute to depress plasma Hcy levels and/or that in some instances it would even produce an increase. As a result, the question about the nature of the relationship between Hcy and physical activity remains unanswered.

Impaired central hemodynamic response and exaggerated vasoconstriction during muscle metaboreflex activation in heart failure patients.

The muscle metaboreflex is enhanced in chronic heart failure (CHF) patients, and this fact has been associated with the early fatigue shown by these patients in response to exercise. In animal studies of CHF, it was found that the limited capacity to enhance ventricular performance is responsible for a functional shift from a cardiac output to a systemic vascular resistance (SVR) increase in the mechanism by which the cardiovascular system raises blood pressure in response to the metaboreflex. However, the existence of this functional shift is still unknown in humans.

Role of the trigeminal nerve in regrowth of hypoglossal motoneurons after hypoglossal-facial anastomosis.

Conclusion. Functional recovery of facial muscles following hypoglossal-facial anastomosis (HFA) may be dependent not only on sensory information, relayed via the trigeminal nuclei to the hypoglossal nucleus, but also on extratrigeminal fibers, originating from the hypoglossal nucleus that travel in the infraorbital nerve (ION). This fact helps to explain the ability of hypoglossal neurons, after HFA, to induce contractions of muscles originally innervated from other nervous structures.

Plasma creatinine and creatine quantification by capillary electrophoresis diode array detector.

Traditional clinical assays for nonprotein nitrogen compounds, such as creatine and creatinine, have focused on the use of enzymes or chemical reactions that allow measurement of each analyte separately. Most of these assays are mainly directed to urine quantification, so that their applicability on plasma samples is frequently hard to perform. This work describes a simple free zone capillary electrophoresis method for the simultaneous measurement of creatinine and creatine in human plasma.

The vestibulospinal reflex in humans: effects on paraspinal muscle activity.

Objective: To elucidate the electromyographic (EMG) patterns elicited in the superficial paraspinal muscles (sacrospinalis, ileocostalis lomborum, longissimus dorsi and splenium cervicis).

Material And Methods: In normal subjects adapted to the dark and standing on a force platform, EMG patterns were elicited in the superficial paraspinal muscles by means of unilateral cold caloric stimulation of the labyrinth.

Results: Almost concomitantly with the occurrence of postural derangement of the subject's trunk and head, the EMG patterns of the paraspinal muscles on both sides showed significant and consistent changes.

Olfactory-hypoglossal connections.

Natural olfactory stimulation with amyl acetate significantly modulates the electrical activity of hypoglossal neurons and the electromyographic responses of the tongue musculature. The aim of the present study was to identify and characterize, using neuroanatomical and neurophysiological approaches, the pathways involved in the transmission of the olfactory information to the hypoglossal nucleus (XIIn). The neuroanatomical findings provided the initial demonstration that olfactory information is conveyed from the olfactory bulb to the hypoglossal nucleus via the interpeduncular nucleus (IPn) by both fast disynaptic and different polysynaptic pathways.