Neuroscience
-
In this study, we investigated whether two brain regions, the bed nucleus of the stria terminalis (BNST) and the basolateral amygdala (BLA), affected male rats' (Rattus norvigicus) ability to innately discriminate between a predator odor (cat urine) and female rat urine. Muscimol, a GABAa receptor agonist, was bilaterally microinjected into either the BNST or BLA of rats through implanted stainless-steel guide cannulas to temporarily inactivate these brain nuclei. ⋯ Furthermore, intra-BNST infusion of muscimol caused rats to be equally attracted to urine from cats and female rats but intra-BLA infusion did not stop rats manifesting fear on exposure to cat urine and exploratory behavior on exposure to female rat urine. We conclude that the BNST plays a more crucial role in modulating innate fear responses in rats than the BLA.
-
Very little is known about the development of cardiac parasympathetic ganglia and cholinergic innervation of the mouse heart. Accordingly, we evaluated the growth of cholinergic neurons and nerve fibers in mouse hearts from embryonic day 18.5 (E18.5) through postnatal day 21(P21). Cholinergic perikarya and varicose nerve fibers were identified in paraffin sections immunostained for the vesicular acetylcholine transporter (VAChT). ⋯ The abundance and distribution of S100-positive Schwann cells increased postnatally along with nerve density. While S100 staining of cardiac Schwann cells was maintained in P21 and older mice, Schwann cells did not show B-FABP staining at these times. Parallel development of satellite cells and cholinergic perikarya in the cardiac ganglia and the increase in abundance of Schwann cells and varicose cholinergic nerve fibers in the atria suggest that neuronal-glial interactions could be important for development of the parasympathetic nervous system in the heart.
-
The aim of this study was to explore, during adolescence, alterations in the use of a sensori-motor representation as unveiled by the measurement of anticipatory postural control in a bimanual load-lifting task. We hypothesised that adolescence constitutes a period of refinement of anticipatory postural control due to on-going updates of the body schema and sensori-motor representations. The anticipatory postural control was assessed using a bimanual load-lifting paradigm in which subjects stabilise their left postural forearm, which is supporting an object, while they use their right hand to lift up the object. ⋯ The decrease of activity over postural flexors, which ensure postural stabilisation, appeared later in adolescents with respect to adults. Delayed timing adjustments and increased variability could reflect intense developmental processes underlain by an intense period of CNS maturation during adolescence. We discuss the role of brain maturation in the refinement of sensori-motor representations and the update of body schema.
-
Accumulating evidence supports the hypothesis of ecstasy and amphetamine exhibiting neurotoxic properties in human recreational users. The extent and exact location of neuronal degeneration might also be associated with a specific profile of cognitive deterioration described in polydrug users. Voxel-based morphometry and cortical thickness analyses constantly gain attention for answering the question of associated neurological sequelae. ⋯ Our data support the hypothesis that massive recreational amphetamine-type stimulant polydrug use is associated with a thinning of cortical grey matter. Disrupted neuronal integrity in frontal regions does fit well into models of addiction and the cognitive deterioration in amphetamine-type stimulant polydrug users. The exact neurotoxic mechanisms of polydrug ecstasy and amphetamine use, however, remain speculative.
-
Delta opioid receptors participate to the control of chronic pain and emotional responses. Recent data also identified their implication in spatial memory and drug-context associations pointing to a critical role of hippocampal delta receptors. We examined the distribution of delta receptor-expressing cells in the hippocampus using fluorescent knock-in mice that express a functional delta receptor fused at its carboxyterminus with the green fluorescent protein in place of the native receptor. ⋯ Fine mapping in the dorsal hippocampus confirmed that delta opioid receptors are mainly present in GABAergic neurons. Indeed, they are mostly expressed in parvalbumin-immunopositive neurons both in the Ammon's horn and dentate gyrus. These receptors, therefore, most likely participate in the dynamic regulation of hippocampal activity.