Highlights • GLYX-13 produces antidepressant-like effects for ⩾1 week following a single dose. • GLYX-13 facilitates learning and memory for ⩾1 week following a single dose. • GLYX-13 enhances ...hippocampal metaplasticity 24 h – 2 weeks following a single dose. • Repeat doses of GLYX-13 maintained the metaplasticity effects for at least 8 weeks. • GLYX-13 increased the number of mature dendritic spines 24 h after a single dose.
Oxytocin (OT) acts as a neuromodulator/neurotransmitter within the central nervous system (CNS) and regulates a diverse range of CNS functions. Notably, evidence from studies in females has revealed ...an important role for OT in regulating anxiety behavior.
The objective of this study was to examine the effects of OT on both behavioral and autonomic parameters of the anxiety response in male mice using three pharmacologically validated preclinical models of anxiety: the four-plate test (FPT), elevated zero maze (EZM), and stress-induced hyperthermia (SIH).
In the FPT, both peripherally (3-30 mg/kg i.p.) and centrally (1-10 microg i.c.v.) administered OT produced dose-dependent increases in punished crossings, indicating an anxiolytic-like effect. The effects of centrally administered OT in the FPT were blocked with peripheral administration of a brain-penetrant OT receptor (OTR) antagonist WAY-162720 (30 mg/kg i.p.), and the effects of peripherally administered OT were blocked with central administration of a non-penetrant OTR antagonist L-371,257, suggesting OT acts centrally. In the EZM, centrally administered OT (0.1-1.0 microg, i.c.v.) produced significant increases in the percentage time spent in the open quadrants of the maze, comparable to alprazolam (0.5-1.0 microg, i.c.v.). In SIH, OT (1-10 mg/kg i.p.) dose-dependently attenuated stress-induced increases in core body temperature, comparable to the reference anxiolytic chlordiazepoxide (CDP) (10 mg/kg i.p.).
These results provide specific behavioral and autonomic evidence of anxiolytic-like effects for oxytocin in males and, together with previously reported observations in females, suggest the potential utility of OTR agonism as a therapeutically relevant mechanism of action for novel anxiolytics in both sexes.
•Early life dietary factors impact neuronal dendritic spine structure.•Milk fat globule membrane and lactoferrin increased total dendritic spine density.•These changes were largely driven by ...hippocampal thin and mushroom spine types.
Early life nutrition plays an important role in brain development. Emerging research in rodents, piglets and humans suggest that prebiotics, milk fat globule membrane and lactoferrin may each play unique roles in brain development and cognitive functions. However, knowledge of their combined impact is lacking. We show here that providing weanling rats with a diet containing milk fat globule membrane, lactoferrin and a polydextrose/galactooligosaccharide prebiotic blend led to a significant increase in total dendritic spine density in hippocampal dentate gyrus neurons. Region-specific alterations in dendritic spine density and morphology could provide a mechanistic basis underlying broader cognitive benefits, but further research is required to demonstrate functional consequences of these observations.
Structural studies have shown that chronic regimens of psychostimulants increase dendritic spine number in the rat striatum. The present study used Western blotting and radioimmunocytochemistry to ...examine psychostimulant‐induced changes in the levels of spinophilin, a protein found abundantly in dendritic spines. Spinophilin determinations were conducted in striatum as well as several other subcortical regions implicated in psychostimulant‐induced neuroplasticity. Rats received an escalating (1–8 mg/kg) dosing regimen of d‐amphetamine (twice daily, i.p.) for 5 weeks, were tested for locomotor sensitization, and were killed 28 days later. This amphetamine dosing regimen was found to induce a significant sensitization of locomotor activity in these animals. Using both Western blotting and radioimmunocytochemistry, spinophilin protein was found to be upregulated in the striatum of amphetamine‐treated rats. In addition, radioimmunocytochemistry revealed that spinophilin was increased in the septum, hippocampus, amygdala and the cingulate cortex, and was unchanged in sensorimotor cortices. Because it binds to F‐actin and protein phosphatase‐1, spinophilin has been proposed as a protein linking synaptic transmission to changes in spine morphology. Radioimmunocytochemistry for spinophilin provides a novel approach to identification of brain regions whose neurons undergo dendritic change after chronic exposure to drugs of abuse.
Numerous studies in this lab and others have reported psychostimulant-induced alterations in both synaptic protein expression and synaptic density in striatum and prefrontal cortex. Recently we have ...shown that chronic d-amphetamine (d-AMPH) administration in rats increased synaptic protein expression in striatum and limbic brain regions including hippocampus, amygdala, septum, and paraventricular nucleus of the thalamus (PVT). Potential synaptic changes in thalamic nuclei are interesting since the thalamus serves as a gateway to cerebral cortex and a nodal point for basal ganglia influences. Therefore we sought to examine drug-induced differences in synaptic protein expression throughout the diencephalon. Rats received an escalating (1–8mg/kg) dosing regimen of d-AMPH for five weeks and were euthanized 28 days later. Radioimmunocytochemistry (RICC) revealed significant upregulation of both spinophilin and the vesicular glutamate transporter, VGLUT1, in PVT, mediodorsal (MD), and ventromedial (VM) thalamic nuclei as well as in lateral hypothalamus (LH) and habenula. Strong positive correlations were observed between VGLUT1 and spinophilin expression in PVT, medial habenula, MD, VM and LH of d-AMPH-treated rats. No significant d-AMPH effect was seen in sensorimotor cortices for either protein. Additionally, no significant differences in the general vesicular protein synaptophysin were observed for any brain region. These findings add to evidence suggesting that long-lasting stimulant-induced synaptic alterations are widespread but not ubiquitous. Moreover, they suggest that d-AMPH-induced synaptic changes may occur preferentially in excitatory synapses.
N 1-Arylsulfonyltryptamines have been identified as 5-HT6 receptor ligands. In particular, N 1-(6-chloroimidazo2,1-b1,3thiazole-5-sulfonyl)tryptamine (11q) is a high affinity, potent full agonist ...(5-HT6 K i = 2 nM, EC50 = 6.5 nM, E max = 95.5%). Compound 11q is selective in a panel of over 40 receptors and ion channels, has good pharmacokinetic profile, has been shown to increase GABA levels in the rat frontal cortex, and is active in the schedule-induced polydipsia model for obsessive compulsive disorders.
N1-Arylsulfonyltryptamines have been identified as 5-HT6 receptor ligands. In particular, N1-(6-chloroimidazo2,1-b1,3thiazole-5-sulfonyl)tryptamine (11q) is a high affinity, potent full agonist ...(5-HT6 Ki = 2 nM, EC50 = 6.5 nM, Emax = 95.5%). Compound 11q is selective in a panel of over 40 receptors and ion channels, has good pharmacokinetic profile, has been shown to increase GABA levels in the rat frontal cortex, and is active in the schedule-induced polydipsia model for obsessive compulsive disorders.
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