Short-term effects of postnatal manipulation on central beta-adrenoceptor transmission

Neonatal handling is known to induce long-lasting changes in behavioral and neuroendocrine responses to stress. Since the central noradrenergic system participates in the adaptive responses to stressful conditions we have analyzed the effects of postnatal handling on beta-adrenoceptor binding sites and isoprenaline- and forskolin-stimulated cyclic AMP accumulation in cerebral cortex, hippocampus and cerebellum of rats at 1 and 3 months of age. Handled animals showed reduced emotional reactivity and lower ACTH and corticosterone secretion after stress. Binding studies using [(3) H]CGP12-177 revealed increased beta-adrenoceptor binding sites in handled rats in cerebellum and cerebral cortex with no changes in hippocampus, and decreased affinity in all cerebral regions. Handling reduced basal levels of cyclic AMP in hippocampus and cerebellum but not in cerebral cortex. The concentration-response curves of cyclic AMP to isoprenaline were displaced to the right in cerebellum of handled rats without differences in Emax; however, Emax was significantly reduced in cerebral cortex and hippocampus. Direct stimulation of the catalytic subunit of adenylyl cyclase by forskolin reduced the efficiency in hippocampus and cerebellum, but not in cerebral cortex of handled animals. It is concluded that neonatal handling reduces the binding properties of beta-adrenoceptor and its primary biochemical responses in the young rat brain, which may account for the reduced responsiveness to stress attained in the handled rats, and may explain the persistence of the effect. The present study emphasizes the role of the central noradrenergic system in modulating the behavioral and neurendocrine responses to neonatal handling.     

Sensory curation: theorizing media use for sensory regulation and implications for family media conflict

ABSTRACT

Media sensory curation theory, introduced here, complements theories of informational, emotional, and relational media gratifications. Sensory curation theory conceptualizes media devices as tools people use to help maintain sensory regulation by simultaneously capturing and curbing sensory input within built and natural environments. This article explicates the theory and introduces the Child and Adult Media Sensory Curation Inventories (MediaSCIs), separate measures of child and adult media sensory behaviors and preferences. A survey of 789 parents and adult caregivers of children ages 3 to 14 revealed moderate to strong correlations between general sensory processing and media sensory curation, validating the MediaSCIs. Controlling usage time, child media sensory curation strongly predicted problematic child media use and moderately predicted adult–child media conflict, which was four times as frequent among adult–child pairs with high MediaSCI scores than with low MediaSCI scores.     

Postnatal handling induces long-term modifications in central beta-noradrenergic signalling in rats

Neonatal handling has been shown to induce a short-term reduction in the binding properties of beta-adrenoceptors and in their primary biochemical responses in the young rat brain, which may account for the reduced responsiveness to stress observed in the handled rats. We have studied the persistence and duration of these changes in cerebral cortex, cerebellum and hippocampus at successive stages of life in neonatally handled rats. Binding properties of the beta-adrenoceptors in handled animals were essentially similar to those of the control rats from 3 to 24 months of age. However, handling disturbed the efficacy of the beta-adrenoceptor intracellular signalling since the isoprenaline-induced accumulation of cyclic AMP was reduced in cerebral cortex at 1, 12 and 24 months; in cerebellum at 12 and 18 months; and in hippocampus at 3 and 12 months. This effect might be partially dependent on a regulatory action of handling on the adenylyl cyclase enzyme itself since both basal and forskolin-induced accumulation of cyclic AMP were persistently reduced. Therefore, postnatal handling can be considered as an effective intervention that modifies sensitivity to various hormonal and neurochemical signals; these changes may be involved over a long period of time in protection against an excessive response to stress. These results suggest that the long-lasting adaptation of the adenylyl cyclase transduction system, which affects the primary biochemical response of the beta-adrenoceptor, may participate in the effects of this manipulation.