Abstract:Immunohistochemistry was used to evaluate the effects of neonatal handling and aversive stimulation during the first 10 days of life on the number of corticotrophs in the anterior lobe of the pituitary of 11-dayold male Wistar rats. Since adult rats handled during infancy respond with reduced corticosterone secretion in response to stressors and with less behavior inhibition in novel environments, we assumed that neonatal stimulation could affect pituitary morphology during this critical period of cell differe… Show more
“…The central hypothesis of the current study is that neonatal stimulation might induce structural changes in the central nervous system, which would in turn account for the alterations observed in adult life. In order to explain the behavioral and neuroendocrine effects of early handling in an adult animal, it is plausible to raise the hypothesis that early-life stimulation leads to stable, probably structural, alterations, which could explain the behavioral and neuroendocrine effects of neonatal handling (Aguiar, Cadore, Padoin, Barbosa-Coutinho, & Lucion, 1997; Caldji et al, 2000; Hermel et al, 2001; Liu, Diorio, Day, Francis, & Meaney, 2000; Meaney et al, 1996; Sturrock, Smart, & Tricklebank, 1983; Vaid et al, 1997; Veenman et al, 1999). A trace left by the neonatal stimulation in the nervous system could be the cause of the behavioral changes observed in adulthood.…”
Neonatal handling induces long-lasting effects on behaviors and stress responses. The objective of the present study was to analyze the effects of neonatal handling (from the 1st to the 10th day after delivery) on the number of cells and volume of locus coeruleus (LC) nucleus in male and female rats at 4 different ages: 11, 26, 35, and 90 days. Results showed significant reductions in the number of cells and the volume of the LC nucleus in neonatally handled males and females compared with nonhandled rats. Environmental stimulation early in life induced a stable structural change in a central noradrenergic nucleus, which could be one of the causal factors for the behavioral and hormonal alterations observed in adulthood.
“…The central hypothesis of the current study is that neonatal stimulation might induce structural changes in the central nervous system, which would in turn account for the alterations observed in adult life. In order to explain the behavioral and neuroendocrine effects of early handling in an adult animal, it is plausible to raise the hypothesis that early-life stimulation leads to stable, probably structural, alterations, which could explain the behavioral and neuroendocrine effects of neonatal handling (Aguiar, Cadore, Padoin, Barbosa-Coutinho, & Lucion, 1997; Caldji et al, 2000; Hermel et al, 2001; Liu, Diorio, Day, Francis, & Meaney, 2000; Meaney et al, 1996; Sturrock, Smart, & Tricklebank, 1983; Vaid et al, 1997; Veenman et al, 1999). A trace left by the neonatal stimulation in the nervous system could be the cause of the behavioral changes observed in adulthood.…”
Neonatal handling induces long-lasting effects on behaviors and stress responses. The objective of the present study was to analyze the effects of neonatal handling (from the 1st to the 10th day after delivery) on the number of cells and volume of locus coeruleus (LC) nucleus in male and female rats at 4 different ages: 11, 26, 35, and 90 days. Results showed significant reductions in the number of cells and the volume of the LC nucleus in neonatally handled males and females compared with nonhandled rats. Environmental stimulation early in life induced a stable structural change in a central noradrenergic nucleus, which could be one of the causal factors for the behavioral and hormonal alterations observed in adulthood.
“…Previous studies (1-3) have shown that several procedures which stimulate pups during the neonatal period appear to affect the animal's reaction to stress stimulation in adult life, but not the basal quantities of hormones (5,6) or the number of corticotroph cells in the pituitary (17). Similarly, our results showed that neonatal handling induced no change in the number of neurons immunoreactive to tyrosine hydroxylase in hypothalamic nuclei of animals that were not submitted to new stressful stimuli before the cell count.…”
Neonatal handling has long-lasting effects on behavior and stress reactivity. The purpose of the present study was to investigate the effect of neonatal handling on the number of dopaminergic neurons in the hypothalamic nuclei of adult male rats as part of a series of studies that could explain the long-lasting effects of neonatal stimulation. Two groups of Wistar rats were studied: nonhandled (pups were left undisturbed, control) and handled (pups were handled for 1 min once a day during the first 10 days of life). At 75-80 days, the males were anesthetized and the brains were processed for immunohistochemistry. An anti-tyrosine hydroxylase antibody and the avidin-biotinperoxidase method were used. Tyrosine hydroxylase-immunoreactive (TH-IR) neurons were counted bilaterally in the arcuate, paraventricular and periventricular nuclei of the hypothalamus in 30-µm sections at 120-µm intervals. Neonatal handling did not change the number of TH-IR neurons in the arcuate (1021 ± 206, N = 6; 1020 ± 150, N = 6; nonhandled and handled, respectively), paraventricular (584 ± 85, N = 8; 682 ± 62, N = 9) or periventricular (743 ± 118, N = 7; 990 ± 158, N = 7) nuclei of the hypothalamus. The absence of an effect on the number of dopaminergic cells in the hypothalamus indicates that the reduction in the amount of neurons induced by neonatal handling, as shown by other studies, is not a general phenomenon in the brain. Environmental stimuli during the neonatal period have lasting effects on emotional behavior and reactivity to stress in adult animals (1,2). Neonatal handling has been used as an experimental model to examine the mechanisms by which early environmental changes could affect neural systems, leading to stable behavioral and neuroendocrine changes (3-6). This apparently harmless procedure in infancy reduces fear in novel environments (5-7) and the secretion of corticosterone, adrenocorticotrophin and prolactin in response to stressors in adulthood (4-6). Furthermore, preliminary results from our laboratory showed that neonatal manipulation reduced the number of neurons in the medial amygdala, the prefrontal cortex (8) and the locus coeruleus (9), and decreased the number of somatostatinergic neurons in the hypothalamic periventricular nucleus
“…First-Episode Psychosis (FEP) groups were reported to have larger PGs than healthy controls in several (Atmaca 2014;Pariante et al 2004;Takahashi et al 2013) but not all (Gruner et al 2012;Habets et al 2012) studies, and so were their first-degree relatives (Aiello et al 2012;Mondelli et al 2008). One hypothesis is that larger PG volume is due to increased number and size of corticotropes and HPA hyperreactivity (Axelson et al 1992;Pariante et al 2004), although support for this hypothesis from animal studies is limited (Aguiar et al 1997;Füchsl et al 2013). HPA hyperreactivity, in turn, could affect the expression of genes critical in brain development like brain-derived neurotrophic factor (BDNF), especially during puberty, and lead to the onset of psychosis (Aiello et al 2012;Borges et al 2013).…”
Section: Inconsistencies In Mri Studies Of Psychopathologiesmentioning
The pituitary gland (PG) is a key component of the essential endocrine systems in humans and animals, including the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-gonadal, and hypothalamic-pituitary-thyroid axes. Structural changes in the PG are observed in a number of psychiatric disorders. Psychiatric disorders are typically characterized by subtle, time-dependent anatomical changes in the brain, and their study necessitates highly powered, longitudinal investigations. Structural magnetic resonance imaging (MRI) is a non-invasive technology that is ideally suited to detect changes in anatomical structures over time. In this paper, we will review the main findings on pituitary function and structure in the context of healthy development and of psychiatric disorders, with particular emphasis on MRI studies. The latter have not always succeeded in providing a clear theoretical framework of mental disorders, which may be explained by low resolution and differences in preprocessing methods, imprecise segmentation rules that do not account for the anatomical and functional specificity of the anterior and posterior lobes of the PG, and inadequate categorization of clinical subjects. We review those limitations and propose solutions for future research.
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