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Journal Article 2012; 33(6): 631-635 PubMed PMID: 23160224 Citation  Keywords:  Animals, Catecholamines:biosynthesis, Chronic Disease, Dopamine beta-Hydroxylase:metabolism, Functional Laterality:physiology, Hippocampus:enzymology, Male, Norepinephrine Plasma Membrane Transport Proteins:metabolism, Rats, Rats, Wistar, Social Isolation.   

OBJECTIVES: Right-left asymmetry of human brain function has been known for a century. Brain asymmetry and lateralization has been observed at the neurochemical level. At the neurochemical level, it is important to further correlate changes in monoaminergic activity with the synthesis and reuptake of these monoamines. The aim of the present study was to analyze the effect of social isolation on catecholamine stores as well as on the regulation of catecholamine synthesis and uptake in the right and left hippocampus.

METHODS: We examined changes in protein levels of dopamine-β-hydroxylase (DBH), norepinephrine transporter (NET) and vesicular monoamine transporter 2 (VMAT 2) in the right and left hippocampus of socially isolated adult male rats during 12 weeks by Western blot analysis.

RESULTS: Chronic isolation stress reduced norepinephrine content in the right hippocampus. No changes were observed in protein levels of DBH and NET in the right hippocampus, whereas expression of this norepinephrine synthetizing enzyme and transporter were elevated in the left hippocampus. On the other hand, chronic isolation stress caused reduction of VMAT2 protein in the right hippocampus.

CONCLUSION: Our results reveale not only the lateralization of stress regulatory system but they also show that long-term isolation stress produces right-left asymmetry of the hippocampus norepinephrine, different regulation of the catecholamines synthesis and reuptake....

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Journal Article 2011; 32(2): 170-175 PubMed PMID: 21552201 Citation  Keywords:  Animals, Cell Proliferation:drug effects, Dopamine:metabolism, Dose-Response Relationship, Drug, Ethanol:pharmacology, Female, Glutamic Acid:metabolism, Hypothalamus:drug effects, Models, Animal, Neurotransmitter Agents:metabolism, Norepinephrine:metaboli.   

OBJECTIVES: Alcohol induces hyperprolactinemia in both alcoholic men and women, but the mechanism is not fully established. The aim is to investigate the mechanism involved in elevation of serum prolactin level after chronic alcohol administration.

METHODS: In this study, healthy female SD rats were given alcohol for 8 weeks and checked for serum prolactin level by radioimmunoassay. Interior pituitary cell proliferation was determined by immunohistochemistry score of Ki-67, and hypothalamic neurotransmitters were detected by Coulomb HPLC electrochemical array.

RESULTS: We demonstrated that serum prolactin level and wet pituitary weight of alcohol-fed rats were significantly increased. Interior pituitary cell proliferation was significantly enhanced; hypothalamic dopamine, 5-HT and GABA levels were reduced while glutamate level was increased by chronic alcohol administration; hypothalamic noradrenalin level remained unchanged.

CONCLUSION: Our study suggested that chronic alcohol administration resulted in elevated serum prolactin level in normal SD rats probably through enhancing pituitary gland cell proliferation combined with altered hypothalamic neurotransmitters that regulate prolactin level....

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Journal Article 2010; 31(6): 807-813 PubMed PMID: 21196910 Citation  Keywords:  Absorptiometry, Photon:methods, Animals, Bone Density, Bone Remodeling, Bone Resorption, Calcium:blood, Disease Models, Animal, Electric Stimulation:methods, Foot, Injections, Intraperitoneal, Male, Neuropsychological Tests, Norepinephrine:blood, Osteocla.   

OBJECTIVES: Bone remodeling has recently been revealed to be under sympathetic nerve control. The role of the sympathetic nerve system is not clearly understood. The present study aim to explore the effect of chemical sympathectomy and stress on bone remodeling in adult rats.

METHODS: 24 twelve-month-old Wistar rats were divided into three group (sympathectomy, stress and control). The sympathectomy and stress group rats were administered 6-hydroxydopamine (150 mg/kg each day) and saline (1 ml/kg each day) intraperitoneal respectively for one week and exposed to stress procedure for another three weeks. The stress procedure was mild, unpredictable footshock, administered for one hour once daily. Analysis of serum chemistry, microcomputed tomography, dual energy X-ray absorptiometry, biomechanical testing and bone histomorphometry were employed.

RESULTS: The stress group rats showed increased bone resorption in contrast to the sympathectomy and control group rats. The serum level of calcium and phosphorus cations and norepinephrine were enhanced, the cancellous bone volume and bone mineral density were reduced, bone mechanical property such as strength, ductility and toughness were weakened, the osteoclast counts and osteoclast surfaces were increased and the bone formatin rate were decreased significantly in the stress group rats in contrast to the other two groups rats. There was no significant difference of bone remodeling between the sympathectomy group and control group rats.

CONCLUSION: Our study showed stress-increased sympathetic nerve system activity enhanced bone resorption while chemical sympathectomy inhibited bone resorption under stress. We postulate sympathetic neurotransmitter and neuropepitide may play a role in regulating bone remodeling....

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Journal Article 2010; 31(1): 103-112 PubMed PMID: 20150881 Citation  Keywords:  Animals, Female, GABA Antagonists:pharmacology, Ganglia, Sympathetic:drug effects, Gonadal Hormones:secretion, Nerve Growth Factor:metabolism, Neuropeptides:pharmacology, Nitric Oxide:metabolism, Nitric Oxide Synthase Type II:metabolism, Norepinephrine:ph.   

OBJECTIVE: Ovarian steroids are modulated by neural influences. In this work we investigate whether norepinephrine (NE) modifies the vasoactive intestinal peptide (VIP) or neuropeptide Y (NPY) actions in coeliac ganglion (CG) on the ovarian hormone release, and evaluate the participation of nitric oxide (NO), measured as nitrite, and of inducible nitric oxide synthetase (iNOS) protein, nerve growth factor (NGF) and its trkA receptor gene expression in the ovarian response.

METHODS: The study was performed in the ex vivo CG-superior ovarian nerve (SON)-ovary system of rats on diestrus day 2 (D2). CG and ovary were placed in separate compartments connected by the SON and incubated with Krebs-Ringer buffer. After addition of 50 ng/ml VIP, 50 ng/ml NPY, 10-6 M NE, or a mix of VIP+NE or NPY+NE in ganglion, samples from the ovarian compartment were taken at different times throughout 180 minutes to measure progesterone, androstenedione and nitrite levels.

RESULTS: VIP and NPY in ganglion induced an increase of progesterone release that was associated for VIP, but not NPY, with a decrease of ovarian nitrite levels, iNOS protein, and NGF/trkA receptor mRNA expression. By contrast, NE in ganglion decreased progesterone, an effect that was suppressed by addition of propranolol in ganglion, and increased nitrites/iNOS and NGF/trkA receptor expression in ovary. GABA A receptor antagonist bicuculline (20 muM) added in ovarian compartment prevented the inhibitory effect on progesterone caused by NE in CG. Androstenedione was not modified under neuropeptides or NE ganglionic stimulation.

CONCLUSIONS: Finally, results from VIP+NE or NPY+NE in ganglion showed that ovarian response on D2 induced by VIP or NPY alone is moderated by the opposite action of NE, and occurs only on progesterone, the most sensitive steroid to neural action....

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Journal Article 2005; 26(5): 515-520 PubMed PMID: 16264408 Citation  Keywords:  Adrenal Medulla:physiopathology, Adrenocorticotropic Hormone:blood, Animals, Cold Temperature, Corticosterone:blood, Epinephrine:blood, Luminescence, Male, Norepinephrine:blood, Pituitary-Adrenal System:physiopathology, Rats, Rats, Wistar, Restraint, Phys.   

OBJECTIVE: The effects of three different long-term (21 days) stresses: isolation(LTI), forced swimming (LTS) and isolation accompanied by forced swimming (LTI+LTS) on the level of plasma noradrenaline (NA), adrenaline (A), corticosterone (CORT) and adrenocorticotropic hormone (ACTH), both under basal conditions and in response to short-term immobilization and cold as heterotypic additional stressors, were compared.

METHODS: Plasma NA and A were assayed by the radioenzymatic method. Plasma CORT was measured using RIA kits. Plasma ACTH was determined by chemiluminescent method.

RESULTS: LTI produced a significant elevation of basal plasma CORT and ACTH, while basal plasma NA and A concentrations remained unchanged. Combination of long-term isolation and forced swimming, produced a significant elevation of basal plasma ACTH content only, while LTS did not influence the basal level of this hormone. When LTI rats were exposed to immobilization and cold, a significant elevation of plasma NA and A level was recorded. In LTS and LTI+LTS groups of rats exposed to immobilization or cold, increased plasma NA and A levels were observed, but this increase was lower in comparison with that found in LTI rats. No difference in plasma CORT content between the three long-term stressed groups of animals was observed, while plasma ACTH level was significantly more elevated in LTS and LTI+LTS than in LTI rats.

CONCLUSION: Based on these results, it may be concluded that LTI as a psychosocial stress represents a stronger stressor than LTS. Also, daily short-term (15 min, 21 days) swimming stress seems to attenuate the effect of long-term isolation on the activity of sympatho-adrenomedullary system....

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Journal Article 2005; 26(5): 581-592 PubMed PMID: 16264397 Citation  Keywords:  Animals, Arylalkylamine N-Acetyltransferase:antagonists & inhibitors, Data Interpretation, Statistical, Depression, Chemical, Female, In Vitro Techniques, Melatonin:metabolism, Norepinephrine:antagonists & inhibitors, Perfusion, Pineal Gland:cytology, Rad.   

OBJECTIVES: Cell-permeable and specific inhibitors of melatonin secretion are sill lacking among tools of the pineal research. Recently, a large effort has been made in the development of arylalkylamine N-acetyltransferase inhibitors, but in most cases the new drugs were tested exclusively using cell-free assays or non-pineal cells. The aim of the present study was to characterize the effect of N-bromoacetyltryptamine (BAT), the first synthesized cell-permeable inhibitor of arylalkylamine N - acetyltransferase, on melatonin secretion from rat and pig pineal glands.

METHODS: The studies were performed in the superfusion cultures of rat and pig pineal explants. Melatonin secretion was determined by radioimmunoassay (RIA).

RESULTS: BAT strongly inhibited the non-stimulated and norepinephrine - stimulated melatonin secretion from the pig and rat pineal explants, with ED50 0.3 - 0.7 microM. The adrenergic stimulation did not modify significantly the inhibitory potency of BAT on the melatonin release. The decline in melatonin secretion induced by the BAT - treatment was biphasic in both rat and pig pinealocytes, with an initial rapid phase followed by a slow one. The half-time of BAT-induced decline in the non - stimulated and norepinephrine-stimulated melatonin secretion was ca. 25 - 35 minutes. The inhibitory effect of BAT was reversible in pinealocytes of both investigated mammals.

CONCLUSIONS: The results show that BAT is a potent and reversible inhibitor of the melatonin secretion in the mammalian pineal gland and open the way for the use of this inhibitor in investigations on the pinealocyte physiology performed in vitro....

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Journal Article 2005; 26(1): 43-49 PubMed PMID: 15726019 Citation  Keywords:  Adrenergic alpha-Agonists:pharmacology, Adrenergic alpha-Antagonists:administration & dosage, Animals, Atmosphere Exposure Chambers, Atmospheric Pressure, Hypoxia:drug therapy, Injections, Intraventricular, Male, Median Eminence:drug effects, Norepinephri.   

OBJECTIVE: We have previously found that chronic hypoxia inhibited thyrotropin-releasing hormone (TRH) mRNA expression in rat paraventricular nucleus (PVN). This study presented the effects of hypoxia on TRH secretion in rat hypothalamus, and the norepinephrine (NE) involvement in the modulation of TRH secretion during acute hypoxia exposure.

SETTING AND DESIGN: Hypoxia was simulated at altitudes of 5 km (10.8% O2) or 7 km (8.2% O2) in a ventilated hypobaric chamber, and control group was set at local altitude of 2.3 km (15.8% O2). The duration of hypoxia exposure was designed acutely and chronically for 0.5, 2, 24 h, 5, 10, and 30 d, respectively. TRH levels were measured by specific radioimmunoassay.

RESULTS: The results showed that hypoxia of 5 km or 7 km significantly enhanced TRH levels of the ME and PVN, and reduced serum T3 levels in most hypoxia-exposed groups. Intraventricular injection (icv) of NE (4 nmol/L) induced a decrease in TRH levels in the median eminence (ME) and PVN, and an increased serum T3 levels following hypoxia of 7 km exposure for 2 h, compared with icv saline control, indicating TRH release increased. The stimulating effect of NE on the TRH secretion was abolished by icv antagonist of adrenergic alpha2-receptor, yohimbine (40 nmol/L).

CONCLUSIONS: We conclude that acute and chronic hypoxia exposure produces an inhibition of hypothalamic TRH secretion from the ME and PVN. Central adrenergic system may play a stimulating role through alpha2-receptor in the acute hypoxia-modulating TRH release from rat hypothalamus....

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Journal Article 2003; 24(1-2): 46-49 PubMed PMID: 12743531 Citation  Keywords:  Animals, Baclofen:pharmacology, Catecholamines:metabolism, Dopamine:metabolism, Female, GABA Agonists:pharmacology, Hypothalamus:growth & development, Muscimol:pharmacology, Norepinephrine:metabolism, Rats, Rats, Wistar, Receptors, GABA-A:drug effects, Re.   

OBJECTIVES: The aim of the present investigation was to determine whether the catecholaminergic system is involved in gabaergic and serotoninergic effects on gonadotrophin secretion during sexual development. To this end, we studied the effect of GABAergic and serotoninergic systems on hypothalamic catecholamine content at different stages of sexual development.

METHODS: The effect of GABA A and GABA B agonists and 5-hydroxy-L-tryptophan on hypothalamic noradrenaline and dopamine content were determined in prepubertal (16 days old) and peripubertal (30 days old) rats.

RESULTS: At 16 days of age GABA agonists did not modify hypothalamic noradrenaline content, whereas a significant decrease in catecholamine concentration was observed in peripubertal rats at 30 days of age. Similar changes were observed with GABA agonists administration on dopamine hypothalamic levels, i.e no effects at 15 days of age and a significant decrease at 30 days. The administration of 5-hydroxy-l-tryptophan (5-HTP) induced a decrease of hypothalamic concentration of noradrenaline and dopamine at both ages.

CONCLUSION: Results indicate that the GABAergic system modifies the hypothalamic catecholamine content in peripubertal but not in prepubertal rats while serotonin has an inhibitory effect at both stages of sexual maturation. Even though both systems induce similar ontogenic modifications on the gonadotrophin axis (stimulatory effect in prepubertal and inhibitory action in peripubertal and adult rats) the present results appear to indicate that GABAergic and serotoninergic systems regulate gonadotrophin secretion by different hypothalamic mechanisms....

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