A sex comparison of serotonin immunoreactivity and content in the ferret preoptic area/anterior hypothalamus

Previous studies with rats raised the possibility that sexually dimorphic features of the medial preoptic area/anterior hypothalamus (POA/AH) may result, in part, from a sex difference in the serotonergic innervation of this region. We asked whether a similar phenomenon may occur in a carnivore, the ferret. A sexually dimorphic male nucleus of the dorsal POA/AH (Mn-POA/AH) has previously been characterized in Nissl-stained sections of the male ferret forebrain; this nucleus is absent in females. A nondimorphic ventral nucleus of the POA/AH is found in both sexes. In the present study numerous serotonin (5-HT) immunoreactive (ir) fibers were observed in the dorsal POA/AH of gonadectomized adult ferrets of both sexes. By contrast, in both sexes the ventral nucleus of the POA/AH had many fewer 5-HTir fibers. A similar difference in the distribution of immunoreactivity between dorsal and ventral POA/AH was observed for tyrosine hydroxylase (TH) localized in cell bodies and in nerve fibers and for H222ir estrogen receptors localized in cell nuclei. Likewise, in both sexes the content of 5-HT and dopamine (DA), measured by high pressure liquid chromatography with electrochemical detection, were significantly higher in the dorsal than the ventral POA/AH, thereby corroborating observed regional differences in 5-HTir and THir fibers, respectively. The present findings provide no support for the notion that sexually dimorphic cytoarchitectonic features of the dorsal POA/AH in ferrets are associated with a sex difference in the serotonergic innervation of this region.     

Lipoic acid effects on lipid peroxidation level,superoxide dismutase activity and monoamines concentration in rat hippocampus

The purposes of the present work were to verify lipid peroxidation level, superoxide dismutase (SOD) activity and monoamines (dopamine (DA), norepinephrine (NE), serotonin (5-HT)), and their metabolites (3,4-hydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA)) contents in rat hippocampus after lipoic acid (LA) administration. Wistar rats were treated with 0.9% saline (i.p., control group) and LA (10, 20 or 30 mg/kg, i.p., LA10, LA20 and LA30 groups, respectively). After the treatments all groups were observed for 24 h. In LA20 group only there was a significant decrease in lipid peroxidation level. However, no alteration was observed in SOD activity in groups treated with LA. The NE and DA levels were increased only in 20 mg/kg dose of LA in rat hippocampus. Serotonin content and their metabolite 5-HIAA levels was decreased in same dose of LA. On the other hand, DOPAC and HVA levels did not show any significant change. The reduction in lipid peroxidation level and alterations in hippocampal monoamines can be suggested as a possible brain mechanism from this antioxidant. The outcome of the study may have therapeutic implications in the neurodegenerative diseases.     

Monoamines and seizures: microdialysis findings in locus ceruleus and amygdala before and during amygdala kindling

We used microdialysis to determine extracellular concentrations of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) before and during a 1-day amygdala kindling paradigm. Subjects were young cats (<1 year old; n=8; 6 female, 2 male). Consecutive 5-min samples (2 microl/min infusion rate) were obtained from left amygdala and ipsilateral locus ceruleus complex (LC) under 3 experimental conditions lasting 1-h each (n=12 samples per cat per condition): (1) just before amygdala stimulation (baseline), (2) during focal afterdischarge (AD) and (3) during generalized AD. ADs were elicited by electrical stimulation applied to establish thresholds immediately before dialysate collection as well as during each sample collected in focal vs. generalized AD conditions. Sample concentrations were time-adjusted to correspond with sleep vs. waking state and/or focal vs. generalized ADs. Seizure activity was indexed by AD threshold (mA) and duration (s) as well as number and duration of specific clinically evident (behavioral) seizure manifestations. Main results were: (1) Lower baseline concentrations (fmoles per sample) of NE, DA and 5-HT correlated with subsequent increases in duration of focal and generalized AD as well as number of behavioral seizure correlates. (2) When compared to baseline levels, NE, DA and 5-HT concentrations significantly increased only in amygdala during focal AD and in both amygdala and LC during generalized AD. (3) NE and 5-HT concentrations were higher than DA at both collection sites and were selectively associated with increased wakefulness throughout the study.     

Central monoamines and antinociceptive drug action

Experiments were perfomed in rats to elucidate the role of central 5-HT and catecholamines in the mediation of the antinociceptive effects of d-amphetamine, d-p-chloroamphetamine, morphine and aminopyrine. The method of Randall and Selitto (1957) was used for determining the antinociceptive effect.     

The development of monoaminergic brainstem-spinal systems in the North American opossum

Summary Evidence is presented for an early appearance of monoaminergic neurites within the spinal cord of the developing opossum. They are present within the marginal zone before hindlimb movements begin (stage I) and they start to grow into the intermediate zone by the time hindlimb movements are first observed (stage II). Monoaminergic neurites grow first into the dorsolateral intermediate zone and the intermediolateral cell column where they can be found by the beginning of stage II. Shortly thereafter, fluorescent varicosities can be traced into the area dorsal to the central canal presumed to become lamina X. Fluorescent processes extend in to the ventral intermediate zone (ventral horn) somewhat later in development. Monoaminergic axons have grown into all of the areas they occupy in the adult animal, except for laminae I and II, by the time immature hindlimb movements can be altered by cutting all brainstem projections to the lumbosacral cord (stage III). Monoaminergic innervation of laminae I and II is the last to develope, but it is present by the time thoracic transection produces complete spinal shock.This investigation was supported by U.S.P.H.S. Grant NS-07410     

Some perspectives on monoamine-opioid peptide interaction in rat central nervous system

Light microscopic immunocytochemistry was employed to investigate possible sites of interaction between the endogenous opioid peptides and monoamines in the rat central nervous system. The opioid and related peptides examined included beta-endorphin (beta-END), alpha-MSH (alpha-MSH) and leucine-enkephalin (Leu-ENK). The monoamines were examined using antisera generated against tyrosine hydroxylase, dopamine-beta-hydroxylase as well as serotonin. Due to the long-tract nature of the central monoamine projections as well as beta-END/alpha-MSH fiber systems, serial section analyses were performed utilizing parasagittal brain sections. Many areas rich in both the monoamines as well as opioid peptides were investigated. These included several thalamic and hypothalamic nuclei, several limbic structures, mesencephalic periaqueductal gray, brain stem noradrenergic cell groups and their rostral projections, the dopaminergic nigrostriatal system, and the serotonergic raphe nuclei and their projections. The results suggest a more intimate linkage between the monoamines and the opioid peptides than previously realized. Some of the intricacies of monoamine-opioid peptide interaction, in particular those pertaining to their possible role in pain and analgesia, catalepsy, and neuroendocrine effects are also discussed.     

Retrograde study of hypocretin-1 (orexin-A) projections to subdivisions of the dorsal raphe nucleus in the rat

A retrograde tracer, WGA-apo-HRP-gold (WG), was injected into each subdivision of the dorsal raphe (DR) nucleus, and subsequent orexin-A immunostaining was performed for the tuberal region of the hypothalamus in order to investigate orexin projections to the DR. Similar to previous studies, the majority of orexin-single-labeled neurons were observed at the dorsal half of the lateral hypothalamus (LH), the circle around the fornix, i.e., perifornical nucleus (PeF), and the area dorsal to the fornix. The present study reports that hypothalamic neurons exhibited differential projections to each subdivision of the DR. Following WG injections into rostral DR, WG-single-labeled cells were observed at the dorsal half of the LH as well as dorsomedial hypothalamic nucleus. The major input to the intermediate DR originates from the ventromedial portion of the LH, PeF, and the area dorsal to the PeF, whereas one to lateral wing DR derived from PeF as well as the ventrolateral portion of the LH. Following WG injections into caudal DR, WG-single-labeled cells were located at ventromedial LH and the ventrolateral portion of the posterior hypothalamus. Following WG injections into each DR subdivision, WG/orexin-double-labeled neurons were observed at LH, PeF, and the area dorsal to the PeF. Only a few double-labeled cells were observed in dorsomedial and posterior hypothalamic nuclei. Our observations suggest that various hypothalamic neurons differentially project to each subdivision of the DR, a portion of which is orexin-immunoreactive. These orexin-immunoreactive DR-projecting hypothalamic neurons might have wake-related influences over a variety of brain functions subject to DR efferent regulation, including affective behavior, autonomic control, nociception, cognition, and sensorimotor integration.     

Effects of repeated hyperbaric nitrogen-oxygen exposures on the striatal dopamine release and on motor disturbances in rats

Previous studies have demonstrated disruptions of motor activities and a decrease of extracellular dopamine level in the striatum of rats exposed to high pressure of nitrogen. Men exposed to nitrogen pressure develop also motor and cognitive disturbances related to inert gas narcosis. After repetitive exposures, adaptation to narcosis was subjectively reported. To study the effects of repetitive exposures to hyperbaric nitrogen-oxygen, male Sprague-Dawley rats were implanted in the striatum with multifiber carbon dopamine-sensitive electrodes. After recovery from surgery, free-moving rats were exposed for 2 h up to 3 MPa of nitrogen-oxygen mixture before and after one daily exposure to 1 MPa of nitrogen-oxygen, for 5 consecutive days. Dopamine release was measured by differential pulse voltammetry and motor activities were quantified using piezo-electric captor. At the first exposure to 3 MPa, the striatal dopamine level decreased during the compression (-15%) to reach -20% during the stay at 3 MPa. Motor activities were increased during compression (+15%) and the first 60 min at constant pressure (+10%). In contrast, at the second exposure to 3 MPa, an increase of dopamine of +15% was obtained during the whole exposure. However, total motor activities remained unchanged as compared to the first exposure. Our results confirm that nitrogen exposure at 3 MPa led to a decreased striatal dopamine release and increased motor disturbances in na?ve rats. Repetitive exposures to 1 MPa of nitrogen induced a reversal effect on the dopamine release which suggests a neurochemical change at the level of the neurotransmitter regulation processes of the basal ganglia. In contrast, motor activity remained quantitatively unchanged, thus suggesting that dopamine is not involved alone in modulating these motor disturbances.     

The effects of sodium arsenite exposure on behavioral parameters in the rat

Arsenic is a metalloid widely present in the environment. It is found in well water, soil, and air, and is also released from mining residues and industrial debris, among other anthropogenic sources. It has been previously reported that the content of catecholamines in striatum, hippocampus, and other cerebral regions changes in mice and rats exposed to arsenic. Few studies have examined behavioral alterations after intoxication with arsenic, and both increased and decreased locomotor activity, as well as learning deficits, have been described. In order to characterize the behavioral alterations induced by arsenic exposure, we exposed adult male Sprague-Dawley rats to 5, 10, and 20 mg/kg of arsenic by intragastric route for 2 or 4 weeks. Exposed rats showed reduced locomotor activity, which returned to control levels at the end of the intoxication period. We also found an increase in the number of errors in an egocentric task, alterations in monoamine content in midbrain and cortex, and increases in arsenic brain concentration, which were related to time of the exposure but not dose. These results indicate that short-term arsenic exposure induces neural and behavioral changes that may reflect a neurotoxic effect, and that these alterations are correlated to dose, time of exposure, and experimental conditions.     

氟对大鼠子代脑单胺类神经介质的影响

Ｗｉｓｔａｒ大鼠自查到阴栓起，分别自由饮用０．６ｍｇ／Ｌ（对照组）、１ｍｇ／Ｌ、５ｍｇ／Ｌ、２５ｍｇ／Ｌ含氟水，其仔鼠饮用同浓度含氟水至９０ｄ，观察胚胎期及生长发育期接触氟对仔鼠大脑功能的影响。采用高压液相色谱－电化学法对大脑单胺类神经介质测定结果显示，除多巴胺的代谢产物之一－３，４－二羟乙酸（ＤＯＰＡＣ）的含量在高剂量组显著降低外，去甲肾上腺素（ＮＥ）、多巴胺（ＤＡ）、高香草酸（ＨＶＡ）、５－羟色胺（５－ＨＴ）和５－羟吲哚乙酸（５－ＨＩＡＡ）的含量与对照组比较均无显著差异，表明氟可抑制ＤＡ的代谢转化，对单胺氧化酶（ＭＡＯ）的活性有一定的抑制作用。提示氟对仔鼠的大脑功能有一定的不良影响。