Sleep research in space: expression of immediate early genes in forebrain structures of rats during the nasa neurolab mission (STS-90).

1. Electrophysiological and behavioural observations have shown that changes in the sleep-waking activity occur in astronauts during the space flight. Experiments performed in ground-based experiments have previously shown that the immediate early gene (IEG) c-fos, a marker of neuronal activation, can be used as a molecular correlate of sleep and waking.

Contribution of REM sleep to Fos and FRA expression in the vestibular nuclei of rat leading to vestibular adaptation during the STS-90 Neurolab Mission.

1. Electrophysical studies performed in ground-based experiments have shown that VN neurons respond to labyrinthine signals following stimulation of macular gravity receptors. Additional evidence indicates that VN neurons may also respond to extralabyrinthine signals of pontine origin, which occur during the PGO waves typical of REM sleep (Bizzi et al.

Responses of Purkinje-cells of the cerebellar anterior vermis to stimulation of vestibular and somatosensory receptors.

In decerebrate cats, sinusoidal rotation of the forepaw around the wrist modifies the activity of the ipsilateral forelimb extensor triceps brachii (TB) and leads to plastic changes of adaptive nature in the gain of vestibulospinal (VS) reflexes (VSRs). Both effects are depressed by functional inactivation of the cerebellar anterior vermis, which also decreases the gain of VSRs. In order to better understand the mechanisms of these phenomena, the simple spike activity of Purkinje (P-) cells was recorded from the vermal cortex of the cerebellar anterior lobe during individual and/or combined stimulation of somatosensory wrist, neck and vestibular receptors.

Adaptive modification of the cats vestibulospinal reflex during sustained and combined roll tilt of the whole animal and forepaw rotation: cerebellar mechanisms.

In decerebrate cats, the electromyogram (EMG) activity of the forelimb extensor triceps brachii (TB) increases during side-down roll tilt of the whole animal (vestibulospinal reflex, VSR) at about 0.15 Hz. (+/-10 degrees ), while decreases during side up tilt.

Proprioceptive neck influences modify the information about tilt direction coded by the cerebellar anterior vermis.

Objective: To verify whether the direction of head tilt coded by the population response of Purkinje (P) cells located in the cerebellar anterior vermis is modified by the relative position of the body with respect to the head.

Material And Methods: In decerebrate cats, the responses of P cells to wobble of the whole animal were analyzed in order to compute the response vectors of the same cells to the labyrinthine input. These response vectors were used to evaluate the population response (vector) of all the recorded neurons to head tilt in specific directions.

Gene expression in autonomic areas of the medulla and the central nucleus of the amygdala in rats during and after space flight.

During space flight astronauts show vestibular-related changes in balance, eye movements, and spontaneous and reflex control of cardiovascular, respiratory and gastrointestinal function, sometimes associated with space motion sickness. These symptoms undergo compensation over time. Here we used changes in the expression of two immediate-early gene (IEG) products to identify cellular and molecular changes occurring in autonomic brainstem regions of adult male albino rats killed at different times during the Neurolab Space Mission (STS-90).

Fos and FRA protein expression in rat precerebellar structures during the Neurolab Space Mission.

Changes in gene expression were examined in precerebellar structures during and after space flight. These structures included the inferior olive (IO), the source of climbing fibers, and the lateral reticular nucleus (LRt) and basilar pontine nuclei (PN), sources of mossy fibers. We examined two immediate early gene products with two different time courses of expression: Fos, which persists only for a few (6-8)h after activation and FRA expression, which lasts for longer periods of time, i.

Short-term (Fos) and long-term (FRA) protein expression in rat locus coeruleus neurons during the neurolab mission: contribution of altered gravitational fields, stress, and other factors.

Changes in immediate-early gene (IEG) expression during and after space flight were studied in the rat locus coeruleus (LC) during the NASA Neurolab mission. The LC sends widespread projections throughout the brain and releases the neuromodulator norepinephrine. LC neurons respond to natural vestibular stimulation; their firing rate also increases during waking and decreases or ceases during sleep.

Fos and FRA protein expression in rat nucleus paragigantocellularis lateralis during different space flight conditions.

The nucleus paragigantocellularis lateralis (LPGi) exerts a prominent excitatory influence over locus coeruleus (LC) neurons, which respond to gravity signals. We investigated whether adult albino rats exposed to different gravitational fields during the NASA Neurolab Mission (STS-90) showed changes in Fos and Fos-related antigen (FRA) protein expression in the LPGi and related cardiovascular, vasomotor, and respiratory areas. Fos and FRA proteins are induced rapidly by external stimuli and return to basal levels within hours (Fos) or days (FRA) after stimulation.

Gene expression in rat vestibular and reticular structures during and after space flight.

Space flight produces profound changes of neuronal activity in the mammalian vestibular and reticular systems, affecting postural and motor functions. These changes are compensated over time by plastic alterations in the brain. Immediate early genes (IEGs) are useful indicators of both activity changes and neuronal plasticity.

Pineal gland hormone and idiopathic scoliosis: possible effect of melatonin on sleep-related postural mechanisms.

Experimental and clinical evidences indicate that endocrine mechanisms, particularly involving the pineal gland, exert a role in the development of postural deficits leading to the occurrence of idiopatic scoliosis (IS). In particular, experiments performed in bipedal animals have shown that removal of the pineal gland, which secretes melatonin (M), induced a scoliosis, and that in such preparations, administration of this hormone prevented the development of this deformity (cf. 131).

Tonic gravity changes alter gene expression in the efferent vestibular nucleus.

To assess effects of tonic gravity changes on efferent vestibular neurons, immediate early gene (IEG) protein expression was compared in the efferent vestibular nucleus (EVe) of adult rats exposed to microgravity during the NASA Neurolab Mission (STS-90), and matching control animals on the ground. Rats sacrificed 1 day and 12 days after launch (experiencing approximately 0g) showed significantly fewer IEG protein-expressing cells than corresponding ground control animals (at 1 g). Normal IEG protein-expressing cell numbers reappeared within I day after flight animals returned to earth, and were maintained at 14 days after landing.

Postural responses of forelimb extensors to somatosensory signals elicited during wrist rotation: interaction with vestibular reflexes.

The responses of the forelimb extensor triceps brachii (TB) to sinusoidal wrist rotation, at 0.156 Hz, +/-5 degrees, were investigated in decerebrate cats. In most of the tested muscles [12/15) the multiunit electromyographic (EMG) activity of the TB muscle increased during dorsiflexion and decreased during plantar flexion of the ipsilateral limb extremity, showing an average (+/-SD) gain of 1.

Fos-related antigens are involved in the transcriptional responses of locus coeruleus neurons to altered gravitational fields in rats.

Locus coeruleus (LC) neurons, which have widespread projections to the whole brain, respond to natural stimulation of macular receptors. Using immunocytochemistry we investigated whether rats exposed to altered gravitational fields showed changes in Fos and Fos-related antigen (FRA) protein levels in the LC. Fos protein is induced very rapidly and returns to basal levels within hours after stimulation, while FRAs persist for days or weeks after induction.

Immediate early gene expression in the vestibular nuclei and related vegetative areas in rats during space flight.

Changes in neuronal activity resulting in somatic and vegetative deficits occur during different space flight conditions. Immediate early genes (IEGs: c-fos and Fos-related antigen [FRA]) are useful indicators of changes in neuronal activity and plasticity. They are induced within minutes of several extracellular stimulations, while the corresponding proteins persist for hours (Fos) or days (FRAs).

Effects of unilateral labyrinthectomy on the norepinephrine content in forebrain and cerebellar structures of albino rats.

Albino (Wistar) rats were used to investigate whether unilateral labyrinthectomy (UL) modified the concentration of norepinephrine (NE) as well as of dopamine (DA) and the corresponding metabolite 3, 4-dihydroxyphenylacetic acid (DOPAC) in different areas of the cerebral and the cerebellar cortex and the striatum. The results obtained in 38 rats submitted to UL were compared to those of 18 rats submitted to sham-operation. The animals were operated under sodium pentobarbital anesthesia and sacrificed 1.

Contribution of the cerebellar anterior vermis to the gain and spatiotemporal properties of the vestibulospinal reflex: a behavioural and cellular analysis.

Functional inactivation of the lobules IV-V of the cerebellar vermis obtained by local microinjection of the GABA-A agonist muscimol, depresses, in decerebrate cats, the amplitude of the VS reflex recorded from the forelimb extensor TB and may occasionally affect its spatial and/or temporal properties. The activity changes induced by tilting the animal head in all the possible directions were uniformely reduced. Experiments of unit recording from the same region submitted in other experiments to the drug injection, revealed that a large proportion of P-cells (67%) showed spatially tuned responses to the labyrinth input, characterized by preferred directions which were uniformely scattered over the horizontal plane.

Neck input modifies the reference frame for coding labyrinthine signals in the cerebellar vermis: a cellular analysis.

The activity of 68 neurons, mainly Purkinje cells, was recorded from the cerebellar anterior vermis of decerebrate cats during wobble of the whole animal (at 0.156 Hz, 5 degrees), a mixture of tilt and rotation, leading to stimulation of labyrinth receptors. Most of the neurons (65/68) were affected by both clockwise and counterclockwise rotations.

Vasopressin in the locus coeruleus and dorsal pontine tegmentum affects posture and vestibulospinal reflexes.

Vasopressin (VP) acts on both the locus coeruleus (LC) neurons and the neighbouring dorsal pontine reticular formation (PRF) neurons by exciting them. Experiments performed in precollicular decerebrate cats have shown that microinjection of 0.25 x 10(-11) micrograms VP into the LC complex of one side increased the extensor rigidity of the ipsilateral limbs, while rigidity of the contralateral limbs remained unmodified or slightly decreased.

Effects of locus coeruleus stimulation on the responses of SI neurons of the rat to controlled natural and electrical stimulation of the skin.

1. The effects of microstimulation of the locus coeruleus (LC) region on the spontaneous discharge and the response of SI neurons to natural and electrical stimulation of the skin have been investigated in 26 urethane anesthetized Sprague-Dawley rats. In particular, one or two air puffs, 5-10 msec in duration, 1-2 psi, usually separated by an interval of 40 msec, were applied on the hairy skin of the wrist or the forepaw at the presentation rate of 1/sec.

Cholinergic neurons of the dorsal pontine tegmentum projecting to the cerebellar vermal cortex of the kitten.

Although the whole cerebellar cortex receives cholinergic afferents, the source of origin of this projection has been clarified only for some corticocerebellar regions. Experiments were performed in kittens to investigate whether the two major cholinergic groups of the brainstem, the pedunculopontine (PPT) and laterodorsal tegmental nuclei (LDT), contribute to the cholinergic innervation of the cerebellar cortex, in particular the vermal cortex. Tegmento-cerebellar projecting neurons were identified by injecting the retrograde tracer rhodamine-labeled latex microspheres in the lobules V to VII of the cerebellar vermis.