Abstract The neonatal ventral hippocampal lesion (NVHL) is an established neurodevelopmental rat model of schizophrenia. Rats with NVHL exhibit several behavioral, molecular and physiological ...abnormalities that are similar to those found in schizophrenics. Schizophrenia is a severe psychiatric illness characterized by profound disturbances of mental functions including neurophysiological deficits in brain information processing. These deficits can be assessed by auditory evoked potentials (AEPs), where schizophrenics exhibit abnormalities in amplitude, duration and latency of such AEPs. The aim of the present study was to compare the density of cells in the temporal cerebral cortex and the N40-AEP of adult NVHL rats versus adult sham rats. We found that rats with NVHL exhibit significant lower amplitude of the N40-AEP and a significant lower number of cells in bilateral regions of the temporal cerebral cortex compared to sham rats. Because the AEP recordings were obtained from anesthetized rats, we suggest that NVHL leads to inappropriate innervation in thalamic-cortical pathways in the adult rat, leading to altered function of cortical networks involved in processing of primary auditory information.
Highlights ► We examine the effect of the thalamic reticular nucleus lesion in rats. ► Thalamic reticular nucleus damage induced a reduction in the exploratory behavior. ► Neuronal hypotrophy in PFC ...and NAcc neurons is observed in these rats. ► Reduced spinogenesis in the CA1 ventral hippocampus also was observed in these rats.
Highlights • We examined the effect of neonatal olfactory bulbectomy (nOBX) at pre-pubertal and post-pubertal age. • Behavior and Binding of NMDA receptors were assessed. • Alterations in the ...locomotion and exploratory behavior were observed in nOBX rats at pre-pubertal age. • At pre-pubertal age, rats with nOBX show increase in NMDA binding.
Usually, most commercial platforms that adapt to the stereotaxic apparatus in neonatal rats or small animals, to carry out surgery are very expensive. Moreover, the operator must have certain ...experience in its handling.
The present work presents two platforms, one of them made in acrylic and the other of expanded polystyrene. These adapt perfectly to conventional stereotaxic apparatus, while operator does not require a great entrainment to carry out the surgical procedure. Histological slides of the prefrontal cortex, ventral hippocampus and basolateral amygdala from adult rats (postnatal day 70), staining with cresyl violet are shown. The neonatal lesions were made at postnatal day 7 with ibotenic acid applied in the prefrontal cortex, ventral hippocampus or basolateral amygdala.
The present data suggest that it is possible to carry out lesions or to apply drugs in neonatal rats, by using an acrylic or expanded polystyrene adaptor for the stereotaxic apparatus. These have the advantage of being economic and having a simple design. Also, the type of anesthesia used in neonatal lesion rats, is discussed.
Pregnancy is a complex process, involving a number of hormones and trophic factors, many of which are formed in the placenta. Several of these trophic factors have an effect at the neuronal level, ...such as BDNF. Consequently, recent reports have shown that exposure to these hormones (estrogen and progesterone) and trophic factors such as BDNF exert a neuroprotective effect. Here, we study the effect of the number of pregnancies on dendritic morphology of aged female rats (18 months of age). Rats of the 18-month-old Sprague Dawley strain with zero, one, two, and three gestations were evaluated for locomotor activity, and Golgi-Cox stain was performed to evaluate the dendritic morphology parameters, the number of dendritic spines, total dendritic length, and branching order number. Adult nulliparous rats (3 months of age) were used as another control group. Adult nulliparous and aging rats with two pregnancies showed an increase in locomotor activity. Adult nulliparous showed an increase in the dendritic spine number compared to old nulliparous rats in both layers of the PFC, the DG, and NAcc. Old rats with two and three pregnancies also showed an increase in the number of dendritic spines compared to old nulliparous rats in layers 3 and 5 of the PFC and in the CA1. Aging animals with one pregnancy also showed an increase in dendritic length compared to old nulliparous rats in the CA1. Our results clearly suggest that two and three pregnancies increase the dendritic spines number in the PFC and CA1 of aged female rats.
Little has been investigated about the effects of stress on synaptic communication at prepubertal age, a stage considered as juvenile. This period of development is related to socialization through ...play. Our group has studied the changes of neuronal morphology in limbic structures caused by stress at prenatal and at early postnatal ages (before weaning) in the rat. In the present study, we assessed the effect of restraint stress at juvenile ages. Male Sprague-Dawley rats from postnatal day (PD) 21 to PD35 were restrained (from movement) for 2 hrs. Locomotor activity in a novel environment was evaluated at three different ages, prepubertal PD38, pubertal PD50, and postpubertal PD68. Using the Golgi-Cox procedure, the dendritic morphology was evaluated in the pyramidal neurons of the prefrontal cortex (PFC), hippocampus, and basolateral amygdala (BLA). Juvenile stress caused a reduced locomotor activity at PD38 and PD68 together with reduction in dendritic spines after puberty in the PFC and at all the studied ages in the BLA. In addition, dendritic length was also reduced in the PFC at PD38 and PD68 and CA1 of the ventral hippocampus at PD50 and PD68. Our results suggest that stress in the juvenile stage can cause changes at the level of behavior and synaptic communication with an effect that remains until adulthood.
Subduction of the Cocos plate and collision of the Cocos Ridge have profound effects on the kinematics of the western Caribbean, including crustal shortening, segmentation of the overriding plate, ...and tectonic escape of the Central American fore arc (CAFA). Tectonic models of the Panama Region (PR) have ranged from a rigid block to a deforming plate boundary zone. Recent expansion of GPS networks in Panama, Costa Rica, and Colombia makes it possible to constrain the kinematics of the PR. We present an improved kinematic block model for the western Caribbean, using this improved GPS network to test a suite of tectonic models describing the kinematics of this region. The best fit model predicts an Euler vector for the counterclockwise rotation of the CAFA relative to the Caribbean plate at 89.10°W, 7.74°N, 1.193° Ma−1, which is expressed as northwest‐directed relative block rates of 11.3 ± 1.0–16.5 ± 1.1 mm a−1 from northern Costa Rica to Guatemala. This model also predicts high coupling along the Nicoya and Osa segments of the Middle American subduction zone. Our models demonstrate that the PR acts as a single tectonic block, the Panama block, with a predicted Euler vector of 107.65°W, 26.50°N, 0.133° Ma−1. This rotation manifests as northeast migration of the Panama block at rates of 6.9 ± 4.0–7.8 ± 4.8 mm a−1 from southern Costa Rica to eastern Panama. We interpret this motion as tectonic escape from Cocos Ridge collision, redirected by collision with the North Andes block, which migrates to the northwest at 12.2 ± 1.2 mm a−1.
Key Points
Collision of the Cocos Ridge is responsible for the upper plate kinematics
The Panama Region acts as a single tectonic block, migrating northeast
Interseismic coupling is high along the Nicoya and Osa segments of the trench
Sleep is a fundamental state necessary for maintenance of physical and neurological homeostasis throughout life. Several studies regarding the functions of sleep have been focused on effects of sleep ...deprivation on synaptic plasticity at a molecular and electrophysiological level, and only a few studies have studied sleep function from a structural perspective. Moreover, during normal aging, sleep architecture displays some changes that could affect normal development in the elderly. In this study, using a Golgi-Cox staining followed by Sholl analysis, we evaluate the effects of 24 h of total sleep deprivation on neuronal morphology of pyramidal neurons from Layer III of the prefrontal cortex (PFC) and the dorsal hippocampal CA1 region from male Wistar rats at two different ages (3 and 22 months). We found no differences in total dendritic length and branching length in both analyzed regions after sleep deprivation. Spine density was reduced in the CA1 of young-adults, and interestingly, sleep deprivation increased spine density in PFC of aged animals. Taken together, our results show that 24 h of total sleep deprivation have different effects on synaptic plasticity and could play a beneficial role in cognition during aging.
Schizophrenia is a severe mental disorder with numerous etiological susceptibilities. Maternal infection is a key risk factor for schizophrenia. Prenatal lipopolysaccharide (LPS) infection stimulates ...cytokine production that affects brain development. In the present study, we aimed to investigate the effect of prenatal LPS injection at gestational day (GD) 14–16 on behavioral paradigms, and neuronal morphology in the prefrontal cortex (PFC), basolateral amygdala (BLA), nucleus accumbens (NAcc) and ventral hippocampus (VH) at two critical ages of development: pre-pubertal (postnatal day 35, PD35) and post-pubertal (PD60) age in male rats. We also evaluated the effects of LPS on nitric oxide (NO) and zinc (Zn) levels in seven brain areas (PFC, VH, amygdala, brainstem, striatum and dorsal hippocampus) at PD35 and PD60. LPS induced hyperlocomotion in a novel environment and reduced social contact as well as increased the levels of NO and Zn in the PFC, brainstem and amygdala as observed in other animal models of schizophrenia-related behavior. Furthermore, we found that LPS-treated rats presented post-pubertal neuronal hypertrophy in the PFC and BLA and decreased spine density in the NAcc. The neuronal morphology of neurons in the VH in LPS-treated rats remained unaltered. Interestingly, the anxiogenic-related behavior correlated with neuronal hypertrophy observed in the BLA. Our findings suggest that the behavioral and neural modifications observed in our model could be mediated by the long-lasting alterations in Zn and NO levels in the brain.
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•Maternal LPS administration induces hyperlocomotion at pre- and post-pubertal age.•Maternal LPS administration reduces the time of social contacts post-puberty.•Maternal LPS administration causes neuronal rearrangement post-puberty.•Maternal LPS administration increases nitric oxide and Zinc levels in the brain.•Maternal LPS administration induces long-lasting modifications in the male offspring.
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