Implications of Neural Plasticity in Retinal Prosthesis.

Retinal degenerative diseases such as retinitis pigmentosa cause a progressive loss of photoreceptors that eventually prevents the affected person from perceiving visual sensations. The absence of a visual input produces a neural rewiring cascade that propagates along the visual system. This remodeling occurs first within the retina.

Cholinergic and nitrergic neuronal networks in the goldfish telencephalon.

The general organization of cholinergic and nitrergic elements in the central nervous system seems to be highly conserved among vertebrates, with the involvement of these neurotransmitter systems now well established in sensory, motor and cognitive processing. The goldfish is a widely used animal model in neuroanatomical, neurophysiological, and behavioral research. The purpose of this study was to examine pallial and subpallial cholinoceptive, cholinergic and nitrergic populations in the goldfish telencephalon by means of histochemical and immunohistochemical techniques in order to identify neurons containing acetylcholinesterase (AChE), choline acetyltransferase (ChAT), NADPH-diaphorase (NADPHd), and neuronal nitric oxide synthase (nNOS), and to relate their distribution to their putative functional significance.

Interactions between postnatal sustained hypoxia and intermittent hypoxia in the adulthood to alter brainstem structures and respiratory function.

Neural plasticity is defined as a persistent change in the morphology and/or function based on prior experiences. Plasticity is well evident when the triggering experience occurs early in life, but in the case of respiratory control plasticity, it also can be triggered in adult life. We have combined a 10 days postnatal hypoxic (PH) (0-10 days of age;11% O(2)) and a 15 days intermittent hypoxia (IH) exposures in the adulthood (90-105 days of age; 5% O(2), 40 s/20% O(2), 80 s; 8 h/day) to test if early PH interacts with IH of the adulthood to generate detrimental plastic changes.

Neonatal caffeine treatment up-regulates adenosine receptors in brainstem and hypothalamic cardio-respiratory related nuclei of rat pups.

While neonatal caffeine treatment is commonly used to alleviate apnea of prematurity in neonates and to improve neurological outcomes, its effects on adenosine A₁ and A(2A) receptors (A₁-R and A(2A)-R) are poorly known. We hypothesized that the central pharmacological action of caffeine is mediated by modification of the postnatal development of the adenosinergic system during a critical period. On postnatal days 2-6 (P2-P6) two groups of newborn rats were orally administered water plus glucose and/or caffeine at therapeutic doses to mimic the clinical use of caffeine in human neonates.

Co-localization of nitric oxide synthase and choline acetyltransferase in the brain of the goldfish (Carassius auratus).

This work investigates the nitrergic and cholinergic systems in the brain and spinal cord of the goldfish (Carassius auratus). We studied the immunohistochemical localization of antibodies against the neuronal nitric oxide synthase (nNOS) and choline acetyltransferase (ChAT) by bright-field and confocal microscopy. Nitrergic and cholinergic cells were segregated within the telencephalon, in both dorsal and ventral areas, and co-distributed in some nuclei of the diencephalon, mesencephalon, rhombencephalon, and spinal cord.

Prenatal activation of 5-HT2A receptor induces expression of 5-HT1B receptor in phrenic motoneurons and alters the organization of their premotor network in newborn mice.

In newborn mice of the control [C3H/HeJ (C3H)] and monoamine oxidase A-deficient (Tg8) strains, in which levels of endogenous serotonin (5-HT) were drastically increased, we investigated how 5-HT system dysregulation affected the maturation of phrenic motoneurons (PhMns), which innervate the diaphragm. First, using immunocytochemistry and confocal microscopy, we observed a 5-HT(2A) receptor (5-HT(2A)-R) expression in PhMns of both C3H and Tg8 neonates at the somatic and dendritic levels, whereas 5-HT(1B) receptor (5-HT(1B)-R) expression was observed only in Tg8 PhMns at the somatic level. We investigated the interactions between 5-HT(2A)-R and 5-HT(1B)-R during maturation by treating pregnant C3H mice with a 5-HT(2A)-R agonist (2,5-dimethoxy-4-iodoamphetamine hydrochloride).

Distribution of NADPH-diaphorase and nitric oxide synthase reactivity in the central nervous system of the goldfish (Carassius auratus).

The nitrergic system has been inferred from cells positive to nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry and/or to the neuronal isoform of nitric oxide synthase (nNOS) immunohistochemistry in different species of vertebrates. The aim of the present work was to systematically study the distribution of cell producing nitric oxide in the goldfish (Carassius auratus) brain. To reach this goal, we firstly studied co-localization for NADPHd and nNOS techniques and demonstrated an extensive double labeling.

An experimental approach to the fundamental principles of hemodynamics.

An experimental model has been developed to give students hands-on experience with the fundamental laws of hemodynamics. The proposed experimental setup is of simple construction but permits the precise measurements of physical variables involved in the experience. The model consists in a series of experiments where different basic phenomena are quantitatively investigated, such as the pressure drop in a long straight vessel and in an obstructed vessel, the transition from laminar to turbulent flow, the association of vessels in vascular networks, or the generation of a critical stenosis.

Characterization of efferent projections of chemosensitive neurons in the caudal parapyramidal area of the rat brain.

The caudal parapyramidal area of the rat brain contains a population of neurons that are highly sensitive to an increase in the extracellular hydrogen ion concentration ([H+]o). Some of them fire synchronously with respiration when [H+]o is increased. These chemosensitive neurons are located in the caudal ventrolateral medulla in a medial region, closest to the pyramidal tract, and a lateral region, beneath the lateral reticular nucleus.

Identification of central nervous system neurons innervating the respiratory muscles of the mouse: a transneuronal tracing study.

In recent years, the central control of breathing in mammals has been the subject of numerous studies. The aim of the present one was to characterize the neuronal network projecting to the main respiratory motoneurons, in adult mice. To this end, the morphology and location of the respiratory motoneurons and their sequential connections with other neurons were revealed using a transneuronal tracing technique by means of the rabies virus infection.