Rubén Antonio Vázquez-Roque

Chronic administration of the neurotrophic agent cerebrolysin ameliorates the behavioral and morphological changes induced by neonatal ventral hippocampus lesion in a rat model of schizophrenia.

Neonatal ventral hippocampal lesion (nVHL) in rats has been widely used as a neurodevelopmental model to mimic schizophrenia‐like behaviors. Recently, we reported that nVHLs result in dendritic retraction and spine loss in prefrontal cortex (PFC) pyramidal neurons and medium spiny neurons of the nucleus accumbens (NAcc). Cerebrolysin (Cbl), a neurotrophic peptide mixture, has been reported to ameliorate the synaptic and dendritic pathology in models of aging and neurodevelopmental disorder such as Rett syndrome. This study sought to determine whether Cbl was capable of reducing behavioral and neuronal alterations in nVHL rats. The behavioral analysis included locomotor activity induced by novel environment and amphetamine, social interaction, and sensoriomotor gating. The morphological evaluation included dendritic analysis by using the Golgi‐Cox procedure and stereology to quantify the total cell number in PFC and NAcc. Behavioral data show a reduction in the hyperresponsiveness to novel environment‐ and amphetamine‐induced locomotion, with an increase in the total time spent in social interactions and in prepulse inhibition in Cbl‐treated nVHL rats. In addition, neuropathological analysis of the limbic regions also showed amelioration of dendritic retraction and spine loss in Cbl‐treated nVHL rats. Cbl treatment also ameliorated dendritic pathology and neuronal loss in the PFC and NAcc in nVHL rats. This study demonstrates that Cbl promotes behavioral improvements and recovery of dendritic neuronal damage in postpubertal nVHL rats and suggests that Cbl may have neurotrophic effects in this neurodevelopmental model of schizophrenia. These findings support the possibility that Cbl has beneficial effects in the management of schizophrenia symptoms.

Cerebrolysin modulates pronerve growth factor/nerve growth factor ratio and ameliorates the cholinergic deficit in a transgenic model of Alzheimer's disease

Alzheimers disease (AD) is characterized by degeneration of neocortex, limbic system, and basal forebrain, accompanied by accumulation of amyloid‐β and tangle formation. Cerebrolysin (CBL), a peptide mixture with neurotrophic‐like effects, is reported to improve cognition and activities of daily living in patients with AD. Likewise, CBL reduces synaptic and behavioral deficits in transgenic (tg) mice overexpressing the human amyloid precursor protein (hAPP). The neuroprotective effects of CBL may involve multiple mechanisms, including signaling regulation, control of APP metabolism, and expression of neurotrophic factors. We investigate the effects of CBL in the hAPP tg model of AD on levels of neurotrophic factors, including pro‐nerve growth factor (NGF), NGF, brain‐derived neurotrophic factor (BDNF), neurotropin (NT)‐3, NT4, and ciliary neurotrophic factor (CNTF). Immunoblot analysis demonstrated that levels of pro‐NGF were increased in saline‐treated hAPP tg mice. In contrast, CBL‐treated hAPP tg mice showed levels of pro‐NGF comparable to control and increased levels of mature NGF. Consistently with these results, immunohistochemical analysis demonstrated increased NGF immunoreactivity in the hippocampus of CBL‐treated hAPP tg mice. Protein levels of other neurotrophic factors, including BDNF, NT3, NT4, and CNTF, were unchanged. mRNA levels of NGF and other neurotrophins were also unchanged. Analysis of neurotrophin receptors showed preservation of the levels of TrKA and p75NTR immunoreactivity per cell in the nucleus basalis. Cholinergic cells in the nucleus basalis were reduced in the saline‐treated hAPP tg mice, and treatment with CBL reduced these cholinergic deficits. These results suggest that the neurotrophic effects of CBL might involve modulation of the pro‐NGF/NGF balance and a concomitant protection of cholinergic neurons.

Differential Effects of UCHL1 Modulation on Alpha-Synuclein in PD-Like Models of Alpha-Synucleinopathy

Parkinsons disease (PD) is a progressive neurodegenerative disorder caused by genetic and environmental factors. Abnormal accumulation and aggregation of alpha-synuclein (a-syn) within neurons, and mutations in the a-syn and UCH-L1 genes have been shown to play a role in the pathogenesis of PD. In light of recent reports suggesting an interaction between a-synuclein and UCH-L1, we investigated the effects of UCH-L1 inhibition on a-syn distribution and expression levels in primary neurons and hippocampal tissues derived from non transgenic (non tg) and a-syn over expressing tg mice. We show that suppression of UCH-L1 activity increased a-syn levels in control, non tg neurons, and resulted in a concomitant accumulation of presynaptic a-syn in these neurons. In contrast, blocking UCH-L1 activity in a-syn over expressing neurons decreased a-syn levels, and enhanced its synaptic clearance. In vitro studies verified the LDN-induced inhibition of UCH-L1 had minimal effect on LC3 (a marker of autophagy) in control cells, in cells over expressing a-syn UCH-L1 inhibition resulted in increased LC3 activity. These findings suggest a possible differential role of UCH-L1 function under normal and pathological conditions. Furthermore, in the context of a-syn-induced pathology, modulation of UCH-L1 activity could serve as a therapeutic tool to enhance the autophagy pathway and induce clearance of the observed accumulated/aggregated a-syn species in the PD brain.

Decreased dendritic spine density of neurons of the prefrontal cortex and nucleus accumbens and enhanced amphetamine sensitivity in postpubertal rats after a neonatal amygdala lesion

A neonatal basolateral‐amygdala (nBLA) lesion in rats could be a potential animal model to study the early neurodevelopmental abnormalities associated with the behavioral and morphological brain changes observed in schizophrenia. Morphological alterations in pyramidal neurons from the prefrontal cortex (PFC) have been observed in postmortem schizophrenic brains, mainly because of decreased dendritic arbor and spine density. We assessed the effects of nBLA‐lesion on the dendritic morphology of neurons from the PFC and the nucleus accumbens (NAcc) in rats. nBLA lesions were made on postnatal day 7 (PD7), and later, the dendritic morphology was studied by the Golgi‐Cox stain procedure followed by Sholl analysis at PD35 (prepubertal) and PD60 (adult) ages. We also evaluated the effects of the nBLA‐lesion on locomotor activity caused by a novel environment, apomorphine, and amphetamine. Adult animals with nBLA lesions showed a decreased spine density in pyramidal neurons from the PFC and in medium spiny cells from the NAcc. An increased locomotion in a novel environment and in amphetamine‐treated adult animals with an nBLA‐lesion was observed. Our results indicate that nBLA‐lesion alters the neuronal dendrite morphology of the NAcc and PFC, suggesting a disconnection between these limbic structures. The locomotion paradigms support the idea that dopaminergic transmission is altered in the nBLA lesion model. This could help to understand the consequences of an earlier amygdala dysfunction in schizophrenia. Synapse 63:1143–1153, 2009.

Neonatal ventral hippocampus lesion induces increase in no levels which is attenuated by subchronic haloperidol treatment

Haloperidol is a potent dopamine receptor antagonist and used to treat psychotic disorders, such as schizophrenia. Recent clinical and preclinical studies demonstrated the overactivity of the nitric oxide (NO) system in schizophrenia. Neonatal ventral hippocampal (nVH) lesions in rats have been widely used as a neurodevelopmental model that mimics schizophrenia‐like behaviors. Here, we investigate first whether the nVH lesion causes changes in NO levels in different limbic brain regions in young adults, postnatal day (PD) 81, and second, whether haloperidol treatment from PD60 to PD81 reverses these changes, by determining the accumulation of nitrites. The results show that NO levels at the level of the prefrontal cortex, occipital cortex, and cerebellum are higher in the nVH lesion animals, and that the haloperidol, in part, attenuates these altered NO levels. The NO levels observed in the nVH lesion animals with and without haloperidol treatment may be relevant to behaviors observed in schizophrenia. Synapse 64:941–947, 2010.

Chronic administration of resveratrol prevents morphological changes in prefrontal cortex and hippocampus of aged rats.

Resveratrol may induce its neuroprotective effects by reducing oxidative damage and chronic inflammation apart from improving vascular function and activating longevity genes, it also has the ability to promote the activity of neurotrophic factors. Morphological changes in dendrites of the pyramidal neurons of the prefrontal cortex (PFC) and hippocampus have been reported in the brain of aging humans, or in humans with neurodegenerative diseases such as Alzheimers disease. These changes are reflected particularly in the decrement of both the dendritic tree and spine density. Here we evaluated the effect of resveratrol on the dendrites of pyramidal neurons of the PFC (Layers 3 and 5), CA1‐ and CA3‐dorsal hippocampus (DH) as well as CA1‐ventral hippocampus, dentate gyrus (DG), and medium spiny neurons of the nucleus accumbens of aged rats. 18‐month‐old rats were administered resveratrol (20 mg/kg, orally) daily for 60 days. Dendritic morphology was studied by the Golgi‐Cox stain procedure, followed by Sholl analysis on 20‐month‐old rats. In all resveratrol‐treated rats, a significant increase in dendritic length and spine density in pyramidal neurons of the PFC, CA1, and CA3 of DH was observed. Interestingly, the enhancement in dendritic length was close to the soma in pyramidal neurons of the PFC, whereas in neurons of the DH and DG, the increase in dendritic length was further from the soma. Our results suggest that resveratrol induces modifications of dendritic morphology in the PFC, DH, and DG. These changes may explain the therapeutic effect of resveratrol in aging and in Alzheimers disease. Synapse, 2016.

Chronic cerebrolysin administration attenuates neuronal abnormalities in the basolateral amygdala induced by neonatal ventral hippocampus lesion in the rat

The neonatal ventral hippocampal lesion (nVHL) has emerged as a model of schizophrenia‐related behavior in the rat. Our previous report demonstrated that cerebrolysin (Cbl), a neuropeptide preparation which mimics the action of endogenous neurotrophic factors on brain protection and repair, promoted recovery of dendritic and neuronal damage of the prefrontal cortex and nucleus accumbens and behavioral improvements in postpubertal nVHL rats. We recently demonstrated that nVHL animals exhibit dendritic atrophy and spine loss in the basolateral amygdala (BLA). This study aimed to determine whether Cbl treatment was capable of reducing BLA neuronal alterations observed in nVHL rats. The morphological evaluation included examination of dendrites using the Golgi‐Cox procedure and stereology to quantify the total cell number in BLA. Golgi‐Cox staining revealed that nVHL induced dendritic retraction and spine loss in BLA pyramidal neurons. Stereological analysis demonstrated nVHL also produced a reduction in cells in BLA. Interestingly, repeated Cbl treatment ameliorated dendritic pathology and neuronal loss in the BLA of the nVHL rats. Our data show that Cbl may foster recovery of BLA damage in postpubertal nVHL rats and suggests that the use of neurotrophic agents for the management of some schizophrenia‐related symptoms may present an alternative therapeutic pathway in these disorders. Synapse, 68:31–38, 2014.

Cerebrolysin improves memory and ameliorates neuronal atrophy in spontaneously hypertensive, aged rats

The spontaneously hypertensive (SH) rat has been used as an animal model of vascular dementia (VD). Our previous report showed that, SH rats exhibited dendritic atrophy of pyramidal neurons of the CA1 dorsal hippocampus and layers 3 and 5 of the prefrontal cortex (PFC) at 8 months of age. In addition, we showed that cerebrolysin (Cbl), a neurotrophic peptide mixture, reduces the dendritic atrophy in aged animal models. This study aimed to determine whether Cbl was capable of reducing behavioral and neuronal alterations, in old female SH rats. The level of diastolic and systolic pressure was measured every month for the 6 first months and only animals with more than 160 mm Hg of systolic pressure were used. Female SH rats (6 months old) received 6 months of Cbl treatment. Immediately after the Cbl treatment, two behavioral tests were applied, the Morris water maze test for memory and learning and locomotor activity in novel environments. Immediately after the last behavioral test, dendritic morphology was studied with the Golgi‐Cox stain procedure followed by a Sholl analysis. Clearly, SH rats with Cbl showed an increase in the dendritic length and dendritic spine density of pyramidal neurons in the CA1 in the dorsal hippocampus and layers 3 and 5 of the PFC. Interestingly, Cbl improved memory of the old SH rats. Our results support the possibility that Cbl may have beneficial effects on the management of brain alterations in an animal model with VD. Synapse 70:378–389, 2016.

Dendritic morphology of neurons in prefrontal cortex and ventral hippocampus of rats with neonatal amygdala lesion

Neonatal basolateral amygdala (nBLA) lesions in rats have been widely used as a neurodevelopmental model that mimics schizophrenia‐like behaviors. Recently, we reported that nBLA lesions result in significant decreases in the dendritic spine number of layer 3 prefrontal cortex (PFC) pyramidal cells and medium spiny neurons of the nucleus accumbens (NAcc), which all changes after puberty. At present, we aimed to evaluate the effect of this lesion in pyramidal neurons of CA1 of the ventral hippocampus (VH) and layer 5 of the PFC. In order to assess the effects of nBLA lesions on the dendritic morphology of the PFC and VH neurons, we carried out nBLA lesions in rats on postnatal day (PD) 7, and then we studied the dendritic morphology of these two limbic subregions at prepubertal (PD35) and postpubertal (PD60) ages. Dendritic characteristics were measured by Golgi‐Cox procedure followed by Sholl analysis. We also evaluated the effects of nBLA lesions on the prepulse inhibition (PPI) and acoustic startle responses. The nBLA lesion induced a significant increase in dendritic length of layer 5 pyramidal neurons of the PFC at both ages, with a decrease in the dendritic spines density after puberty. The spine density of CA1 VH pyramidal neurons showed significant decreases at both ages. PPI was decreased in adulthood in the animals with an nBLA lesion. These results show that an nBLA lesion alters the dendritic morphology at the level of the PFC and VH in distinct ways before puberty, suggesting a disconnection between these limbic structures at an early age, and increasing our understanding of the implications of the VH in early amygdala dysfunction in schizophrenia. Synapse, 2012.

Curcuma treatment prevents cognitive deficit and alteration of neuronal morphology in the limbic system of aging rats

Curcuma is a natural compound that has shown neuroprotective properties, and has been reported to prevent aging and improve memory. While the mechanism(s) underlying these effects are unclear, they may be related to increases in neural plasticity. Morphological changes have been reported in neuronal dendrites in the limbic system in animals and elderly humans with cognitive impairment. In this regard, there is a need to use alternative therapies that delay the onset of morphologies and behavioral characteristics of aging. Therefore, the objective of this study was to evaluate the effect of curcuma on cognitive processes and dendritic morphology of neurons in the prefrontal cortex (PFC), the CA1 and CA3 regions of the dorsal hippocampus, the dentate gyrus, and the basolateral amygdala (BLA) of aged rats. 18‐month‐old rats were administered curcuma (100 mg/kg) daily for 60 days. After treatment, recognition memory was assessed using the novel object recognition test. Curcuma‐treated rats showed a significant increase in the exploration quotient. Dendritic morphology was assessed by Golgi–Cox staining and followed by Sholl analysis. Curcuma‐treated rats showed a significant increase in dendritic spine density and dendritic length in pyramidal neurons of the PFC, the CA1 and CA3, and the BLA. The preservation of dendritic morphology was positively correlated with cognitive improvements. Our results suggest that curcuma induces modification of dendritic morphology in the aforementioned regions. These changes may explain how curcuma slows the aging process that has already begun in these animals, preventing deterioration in neuronal morphology of the limbic system and recognition memory.