Changes In Neuropeptide Gene Expression Research Articles

Analysis of primary visual cortex in dementia with Lewy bodies indicates GABAergic involvement associated with recurrent complex visual hallucinations.

Dementia with Lewy bodies (DLB) patients frequently experience well formed recurrent complex visual hallucinations (RCVH). This is associated with reduced blood flow or hypometabolism on imaging of the primary visual cortex. To understand these associations in DLB we used pathological and biochemical analysis of the primary visual cortex to identify changes that could underpin RCVH. Alpha-synuclein or neurofibrillary tangle pathology in primary visual cortex was essentially absent. Neurone density or volume within the primary visual cortex in DLB was also unchanged using unbiased stereology. Microarray analysis, however, demonstrated changes in neuropeptide gene expression and other markers, indicating altered GABAergic neuronal function. Calcium binding protein and GAD65/67 immunohistochemistry showed preserved interneurone populations indicating possible interneurone dysfunction. This was demonstrated by loss of post synaptic GABA receptor markers including gephyrin, GABARAP, and Kif5A, indicating reduced GABAergic synaptic activity. Glutamatergic neuronal signalling was also altered with vesicular glutamate transporter protein and PSD-95 expression being reduced. Changes to the primary visual cortex in DLB indicate that reduced GABAergic transmission may contribute to RCVH in DLB and treatment using targeted GABAergic modulation or similar approaches using glutamatergic modification may be beneficial.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-016-0334-3) contains supplementary material, which is available to authorized users.

Enhanced maternal aggression and associated changes in neuropeptide gene expression in multiparous rats.

Although it has often been speculated that prior reproductive experience improves subsequent maternal care, few studies have examined specific changes in behavior during a 1st versus 2nd lactation. During lactation, mothers display heightened aggression toward male intruders, purportedly to protect vulnerable young. In the current study, maternal aggression was examined in primiparous and age-matched multiparous females on postpartum days 5 (PPD5) and PPD15. Expression of oxytocin, oxytocin receptor, arginine vasopressin, arginine vasopressin V1a receptors, and corticotrophin-releasing hormone mRNA was measured following aggression testing at both time points using real-time quantitative PCR in brain regions previously implicated in the regulation of maternal aggression. Multiparity significantly enhanced maternal aggression on PPD5 but not on PPD15. In addition, this increased aggression was associated with region- and gene-specific changes in mRNA expression. These findings indicate that reproductive experience enhances maternal aggression, an effect that may be mediated by region-specific alterations in neuropeptidergic activity. The adaptations observed in multiparous females provide an innate model for the study of neuroplasticity in the regulation of aggression.

Neuroendocrine changes in adult female rats prenatally exposed to phenytoin

Neuroendocrine changes in fetal hydantoin syndrome have not been described yet. This study was aimed to verify the hypothesis that prenatal exposure to phenytoin influences the stress response of adult female offspring in an animal model. To study possible development of depression like state, hedonic behavior and long-term changes in neuropeptide gene expression in the hypothalamus were investigated. Treatment consisted of per os administration of 150 mg/kg of phenytoin or water daily, from day 7–18 of gestation. Adult female offspring (6 animals per group) were acutely stressed by 1 min handling. Blood was collected in conscious rats via tail artery cannulas before, 1, 15 and 30 min after the handling. Exposure to phenytoin in uterus resulted in increased catecholamine and corticosterone concentrations in response to a mild stressor of 1min handling in adult offspring. The gestational treatment used in this study did not induce a depression like state nor long-term changes in neuropeptide gene expression in the adult offspring. In conclusion, prenatal exposure to phenytoin treatment enhanced the stress response of adult female offspring. Possible new component of fetal hydantoin syndrome is the increase in catecholamine release in response to a mild stressor in adulthood.

Leptin sensitive neurons in the hypothalamus.

A major paradigm in the field of obesity research is the existence of an adipose tissue-brain endocrine axis for the regulation of body weight. Leptin, the peptide mediator of this axis, is secreted by adipose cells. It lowers food intake and body weight by acting in the hypothalamus, a region expressing an abundance of leptin receptors and a variety of neuropeptides that influence food intake and energy balance. Among the most promising candidates for leptin-sensitive cells in the hypothalamus are arcuate nucleus neurons that co-express the anabolic neuropeptides, neuropeptide Y (NPY) and agouti-related peptide (AGRP), and those that express proopiomelanocortin (POMC), the precursor of the catabolic peptide, alphaMSH. These cell types contain mRNA encoding leptin receptors and show changes in neuropeptide gene expression in response to changes in food intake and circulating leptin levels. Decreased leptin signaling in the arcuate nucleus is hypothesized to increase the expression of NPY and AGRP. Levels of leptin receptor mRNA and leptin binding are increased in the arcuate nucleus during fasting, principally in NPY/AGRP neurons. These findings suggest that changes in leptin receptor expression in the arcuate nucleus are inversely associated with changes in leptin signaling, and that the arcuate nucleus is an important target of leptin action in the brain.

Suckling-induced changes in neuropeptide Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat: evaluation of a putative intervention of prolactin.

Hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC)-derived peptides located in the arcuate nucleus (ARC) have been postulated to be good candidates to play a modulatory role during lactation. In the present study, we first quantified, by in situ hybridization, lactation-induced changes in NPY and POMC gene expression throughout the ARC. In a second phase of the study, we attempted to determine whether any relationship exists between neuropeptide gene expression and the suckling stimulus itself. For this, we used experimental groups of animals submitted to suppression of the suckling stimulus by removal of pups and the subsequent restoration of the suckling stimulus by the return of the litter. Since lactation is characterized by an estrogen-deficient status [15], we attempted using ovariectomized (2 or 21 days) diestrous females to describe the changes in NPY gene expression observed during lactation. Since the suckling stimulus induces a strong prolactin (PRL) release, we completed this study by using an intravenous injection of PRL antiserum in order to discriminate the effects of PRL per se on the observed suckling-induced changes in neuropeptide gene expression. Freely nursing lactating females exhibited a large increase in NPY mRNA expression as compared to diestrous females (10.10 +/- 0.50 vs. 4.51 +/- 0.35). After suppression of the suckling stimulus by removal of pups, this increase intensified during short-term suppression of 16 h (15.37 +/- 0.67) and was reversed following long-term suppression of 36 h (12.35 +/- 0.61). Ovariectomized diestrous animals showed significant changes in NPY mRNA expression as compared to lactating females (5.25 +/- 0.42 vs. 10.10 +/- 0.50). Lactating females submitted to PRL immunoneutralization by PRL antiserum showed a slight increase in NPY mRNA expression as compared to non-injected lactating females (13.75 +/- 0.51 vs. 12.95 +/- 0.59). Freely nursing lactating females showed a decrease in POMC mRNA expression (8.27 +/- 0.33) whereas suppression of suckling by removal of the pups (9.52 +/- 0.45) resulted in a return to diestrous POMC mRNA levels (10.77 +/- 0.36). We showed that restoration of suckling by the return of the litter induced an increase in POMC gene expression (12.55 +/- 0.66). By lowering circulating levels of PRL with PRL antiserum after restoration of suckling, we observed a decrease in POMC mRNA expression (9.81 +/- 0.46). Results of this study showed that the increase in NPY mRNA in the medial ARC during lactation did not appear to be due either to gonadal steroid-deficient status or to the suckling-induced hyperprolactinemia. If freely nursing lactating females showed a moderate decrease in POMC gene expression, restoration of the suckling stimulus by return of the pups provoked an increase in POMC gene expression which seemed to depend on high endogenous levels of PRL.

Effects of l-DOPA on preproenkephalin and preprotachykinin gene expression in the MPTP-treated monkey striatum

The cellular expression of the genes encoding the neuropeptides enkephalin and substance P were examined in the caudate nucleus and putamen of parkinsonian 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated cynomolgus monkeys by in situ hybridization using radioactive antisense oligonucleotides coupled with computer-assisted image analysis. Behavioural evaluation of the animals revealed two levels of motor impairment; one group moderately impaired and the other severely disabled. A marked increase in the cellular content of preproenkephalin A messenger RNA was observed in medium-sized (106 +/- 9 microns2) cells in the caudate-putamen of all MPTP animals when compared with controls, the increase being greatest in the most severely impaired animals. By contrast, a marked reduction in the cellular abundance of preprotachykinin gene expression was detected in striatal cells (101 +/- 16 microns2) of these same MPTP animals. These changes in neuropeptide gene expression were not associated with a change in the density (approximately 10 cells per mm2) of messenger RNA-expressing cells. L-DOPA treatment of two of the severely-impaired MPTP monkeys resulted in a dissociation of expression of these two genes: the cellular abundance of preproenkephalin A remained elevated whilst preprotachykinin levels were normalized and comparable with controls. No change in the cellular abundance of preprotachykinin messenger RNA was observed in cells of the insular cortex or a small discrete population of large cells (208 +/- 27 microns2) in the ventral putamen. These results demonstrate that MPTP treatment of primates results in a marked potentiation in preproenkephalin messenger RNA coupled with a attenuation in preprotachykinin messenger RNA in the dopamine-denervated caudate-putamen. L-DOPA therapy given on an intermittent schedule reverses the decrease in preprotachykinin messenger RNA, but fails to reverse the increase in preproenkephalin messenger RNA in the same animal. These observations suggest that a dissociation of the activity of these two neuropeptide systems may underlie the improvement in motor skill that accompanies dopamine replacement therapy and that this dissociation may be instrumental in the long-term complications associated with L-DOPA therapy.

Local anaesthesia prevents acute inflammatory changes in neuropeptide messenger RNA expression in rat dorsal root ganglia neurons

Sensory neuropeptides, synthesised in dorsal root ganglia (DRG), are implicated in neurogenic inflammation and nociception in arthritis. Adjuvant monoarthritis increases primary afferent activity and alters expression of neuropeptide genes in DRG We investigated the role of neural discharge in the early changes in neuropeptide gene expression. Adjuvant injection increased preprotachykinin (PPT) and calcitonin gene-related peptide (CGRP) messenger RNA (mRNA) after 8 h, whereas somatostatin mRNA expression remained unchanged, in innervating L5 DRG neurons. The changes in PPT mRNA expression were prevented by concurrent local anaesthesia of the sciatic nerve. Our results suggest that electrical activity mediates, in part, the changes in DRG gene expression in response to acute inflammation.

Isolation- and dehydration-induced changes in neuropeptide gene expression in the sheep hypothalamus

Changes in neuropeptide gene expression in the hypothalami of sheep subjected to psychological stress (isolation, 1 h; n = 3) or dehydration (48 h; n = 3) were examined using in-situ hybridization histochemistry. Compared with non-stressed euhydrated control animals (n = 3), isolation induced significant accumulation of mRNA for corticotrophin-releasing hormone, pro-enkephalin and pro-dynorphin (DYN) in the paraventricular nucleus (PVN), but no change in mRNA content within the supraoptic nucleus (SON). By contrast, dehydration significantly increased DYN mRNA in the magnocellular neurones of the PVN and SON. However, neither isolation nor dehydration altered the expression of mRNA for vasopressin (AVP) in either the PVN or the SON. These results indicate that in the ovine hypothalamus (1) stress represents a powerful stimulus to co-ordinated neuropeptide synthesis and (2) expression of DYN mRNA and AVP mRNA may be independently regulated during changes in plasma osmolality.