The serotonin transporter gene linked polymorphic region is associated with the behavioral response to repeated stress exposure in infant rhesus macaques

The short allele of the serotonin transporter linked polymorphic region (5-HTTLPR) moderates the effects of stress on vulnerability to mood and anxiety disorders. The mechanism by which this occurs may relate to differential sensitivity to stressful life events. Here we explored whether 5-HTTLPR and sex affected behavioral responses to repeated maternal separation in infant rhesus macaques. Behaviors were collected during the acute (Day 1) and the chronic (Days 2-4) phases of the separation, and the effects of duration of separation (acute vs. chronic), genotype (long/long vs. short allele), and sex (male vs. female) on behavioral responses were analyzed across four successive separations. Males increased their levels of locomotion with repeated maternal separation, whereas females exhibited an increase in frequency of self-directed behavior, a measure of "depression-like" behavior. The short-allele predicted increased environmental exploration, particularly during the chronic phase of social separation, indicative of higher arousal. In addition, the short-allele carriers were more likely to increase their levels of self-directed behavior during the chronic phase of separation, as a function of repeated exposures. These findings suggest that the short allele may increase reactivity to repeated, chronic stressors, leaving them more vulnerable to affective psychopathology, with females particularly vulnerable.     

Effect of eye NGF administration on two animal models of retinal ganglion cells degeneration

The aim of this study was to investigate the effect of nerve growth factor (NGF) administration on retinal ganglion cells (RGCs) in experimentally induced glaucoma (GL) and diabetic retinopathy (DR). GL was induced in adult rats by injection of hypertonic saline into the episcleral vein of the eye and diabetes (DT) was induced by administration of streptozoticin. Control and experimental rats were treated daily with either ocular application of NGF or vehicle solution. We found that both animal models present a progressive degeneration of RGCs and changing NGF and VEGF levels in the retina and optic nerve. We then proved that NGF eye drop administration exerts a protective effect on these models of retinal degeneration. In brief, our findings indicate that NGF can play a protective role against RGC degeneration occurring in GL and DR and suggest that ocular NGF administration might be an effective pharmacological approach.     

Measuring the effects of manipulating stimulus presentation time on sensorimotor alpha and low beta reactivity during hand movement observation

The present study addresses three methodological questions that have been ignored in previous research on EEG indices of the human mirror neuron system (hMNS), particularly in regard to autistic individuals. The first question regards how to elicit the EEG indexed hMNS during movement observation: Is hMNS activation best elicited using long stimulus presentations or multiple short repetitions? The second question regards what EEG sensorimotor frequency bands reflect sensorimotor reactivity during hand movement observation? The third question regards how widespread is the EEG reactivity over the sensorimotor cortex during movement observation? The present study explored sensorimotor alpha and low beta reactivity during hand movement versus static hand or bouncing balls observation and compared two experimental protocols (long exposure vs. multiple repetitions) in the same participants. Results using the multiple repetitions protocol indicated a greater low beta desynchronisation over the sensorimotor cortex during hand movement compared to static hand and bouncing balls observation. This result was not achieved using the long exposure protocol. Therefore, the present study suggests that the multiple repetitions protocol is a more robust protocol to use when exploring the sensorimotor reactivity induced by hand action observation. In addition, sensorimotor low beta desynchronisation was differently modulated during hand movement, static hand and bouncing balls observation (non-biological motion) while it was not the case for sensorimotor alpha and that suggest that low beta may be a more sensitive index of hMNS activation during biological motion observation. In conclusion the present study indicates that sensorimotor reactivity of low beta during hand movement observation was found to be more widespread over the sensorimotor cortex than previously thought.     

Role of serotonergic system in the pathogenesis of fibrosis in canine idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies are muscle diseases characterized by inflammation, necrosis, and fibrosis. The neurotransmitter serotonin (5-HT) has been shown to promote fibrosis in many tissues and organs by activating TGFβ-1 signaling. In this study, we evaluated the potential role of 5-HT in the pathogenesis of fibrosis in canine idiopathic inflammatory myopathies. Muscle biopsies from dogs affected by masticatory muscle myositis or polymyositis and from healthy dogs were processed for immunohistochemistry and Western blotting. The immunohistochemical analysis showed a strong expression of 5-HT in muscle tissues of affected dogs, whereas the amine was absent in the muscles of healthy dogs. Biochemical analysis showed increased expression levels of the selective 5-HT2A receptor in the muscle specimens of the most severely affected dogs versus controls. Further, increased phosphorylation levels of the TGFβ-1 signaling mediators SMAD2/3 and ERK1/2 were detected in tissue samples from affected dogs as compared to tissues from healthy dogs. Although further studies are needed, our findings highlight for the first time a potential role of 5-HT in the development of fibrosis in canine idiopathic inflammatory myopathies, thus supporting other evidence that 5-HT pro-fibrotic activity occurs via activation of TGFβ-1 signaling pathway.