Activation of tuberoinfundibular and tuberohypophysial dopamine neurons following intracerebroventricular administration of bombesin.

The effect of bombesin on the activity of dopamine (DA) neurons comprising the nigrostriatal, mesolimbic, tuberoinfundibular and tuberohypophysial systems in the male rat was determined by measuring: (1) the accumulation of 3,4-dihydroxyphenylalanine (DOPA) after administration of a decarboxylase inhibitor, and (2) the concentration of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in brain (striatum, nucleus accumbens, median eminence) and pituitary regions (intermediate and neural lobes) containing terminals of these neurons. Intracerebroventricular (i.c.v.) injection of bombesin caused a dose- and time-related increase in the activity of DA neurons projecting to the median eminence and intermediate lobe of the pituitary, and a corresponding decrease in the concentrations of prolactin and alpha-melanocyte-stimulating hormone (alpha MSH) in the plasma. In contrast, doses of bombesin up to 10 ng i.c.v. failed to alter the activity of DA neurons terminating in the striatum, nucleus accumbens or neural lobe of the pituitary gland. Equimolar doses of bombesin and gastrin-releasing peptide (GRP), a bombesin-like peptide, increased the concentrations of DOPAC in the median eminence and intermediate lobe of the pituitary, suggesting that GRP-preferring receptors may be responsible for the stimulatory effects of bombesin on DA neuronal activity in these regions. The results of these studies suggest that bombesin increases the activity of tuberoinfundibular and tuberohypophysial DA neurons projecting to the median eminence and intermediate lobe of the pituitary, respectively, and thereby inhibits the secretion of prolactin and alpha MSH.     

Biogenic amine levels in the mid-term human fetus

Spectrophotofluorometric assays were used to measure concentrations of DA, NA, 5-HT and 5-HIAA present in extracts of brain tissue and CSF taken from midterm gestational fetuses of both sexes. The presence of biogenic amines was demonstrated in fetuses as early as 10.5 weeks gestation. In the hypothalamus, the concentrations (expressed in ng/100 mg tissue) ranged from 10.2 to 62.2 for NA, 11.6 to 258.8 for DA, 7.6 to 38.6 for 5-HT and 56.6 to 114.1 for 5-HIAA. Concentrations of DA and 5-HT were found to be significantly (P less than 0.05) higher in the hypothalamus than in the cortex, but those of NA and 5-HIAA were similar in both areas. No sex difference was observed. The concentrations of biogenic amines in the CSF (expressed in ng/ml) were 63.1-286.7 for NA, 43.2-108.1 for DA, 30.9-87.5 for 5-HT and 8.0-42.8 for 5-HIAA.     

Atrial natriuretic peptide-induced suppression of basal and dehydration-induced vasopressin secretion is not mediated by hypothalamic tuberohypophysial or tuberoinfundibular dopaminergic neurons

The purpose of this study was to examine the effects of atrial natriuretic peptide (ANP) on the secretion of vasopressin and the activities of hypothalamic tuberohypophysial and tuberoinfundibular dopaminergic neurons in normal and dehydrated male rats. Neuronal activity was estimated by measuring the concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) and dopamine (DA) in brain and posterior pituitary regions containing terminals of tuberohypophysial (neural lobe; intermediate lobe) and tuberoinfundibular (median eminence) DA neurons. Intracerebroventricular (icv) administration of 20 micrograms ANP decreased basal arginine vasopressin concentrations in the plasma, but had no effect on the concentrations of DOPAC or DA in any region examined. Water deprivation caused a time-dependent increase in plasma arginine vasopressin concentrations, with maximal levels measured 2 days after removal of water bottles. Water deprivation had no effect on DOPAC concentrations in the neural lobe, intermediate lobe or median eminence, but increased DA concentrations in the neural lobe. ANP (20 micrograms/rat; icv) decreased arginine vasopressin concentrations in the plasma of water-deprived rats without altering DOPAC or DA concentrations in the neural lobe, intermediate lobe or median eminence. These results indicate that ANP-induced suppression of basal and dehydration-induced vasopressin secretion is not mediated by tuberohypophysial or tuberoinfundibular DA neurons.     

Selective changes in the contents of noradrenaline, dopamine and serotonin in rat brain areas during aging

This study examines the age-associated changes in noradrenaline (NA), dopamine (DA), 3,4-dihydroxyphenyl-acetic acid (DOPAC), serotonin (5-HT) and 5-hydroxy-3-indoleacetic acid (5-HIAA) in different brain areas of rats. DA and DOPAC concentrations in striatum increased at third month of age, remaining without significant variations until 12th month of age, and decreasing in 24-month-old rats. DA concentration dropped in hippocampus, amygdala and brainstem of 24-month-old-rats, whereas DOPAC levels decreased only in hippocampus. These changes suggest an age-dependent deficit of the dopaminergic system, presumably related to a reduced number/activity of DA nigrostriatal and mesolimbic neurons. An age-induced decline in NA content was found in the pons-medulla, the area containing NA neuronal bodies. Concentrations of 5-HT were reduced with aging in frontal cortex, showing a tendency to decrease in all brain areas examined. The increased 5-HIAA/5-HT ratio found in frontal cortex, amygdala and striatum suggests an age-related decreased synthesis and an accelerated 5-HT metabolism. The 5-HIAA content decreased in brainstem of the oldest rats. These findings point to a selective impairment of nigrostriatal and mesolimbic DA in aging rats, whereas reductions in NA were restricted to cell bodies region and 5-HT showed changes of different extent in areas of terminals and neuronal cell bodies.     

Regional differences in the effect of pargyline on dopamine concentrations in the rat hypophysis

Summary Dopamine concentrations were estimated in different regions of the infundibular-pituitary system of the rat. The highest values were found in the pituitary stalk where they are comparable to the concentrations in the striatum, and higher than in the median eminence.In the anterior lobe the dopamine (DA) concentrations of the upper pole (10% of the lobe tissue) were 2–5 times higher than in the rest of the lobe. Anterior lobe DA was significantly higher in rats about 6 months old than in rats about 3 months old.After inhibition of MAO, the DA concentrations in the isolated neural lobe (NL) were more than doubled. In contrast there was no increase in the DA concentrations of the intermediate lobe, an observation which is in agreement with our previous finding that DA synthesis in the intermediate lobe after electrical stimulation of the pituitary stalk is much slower than in the neural lobe.Pargyline treatment caused an increase in the DA concentrations in the anterior lobe by about 150%. This rise (together with a DA increase in the stalk-infundibulum) may be related to the decrease in circulating prolactin which occurs in pargyline treated rats.     

The ontogenic appearance of tyrosine hydroxylase-, serotonin-, gamma-aminobutyric acid-, calcitonin gene-related peptide-, substance P-, and synaptophysin-immunoreactivity in rat pituitary gland

The initial appearance of tyrosine hydroxylase (TH)-, serotonin (5-HT)-, gamma-aminobutyric acid (GABA)-, calcitonin gene-related peptide- (CGRP), substance P-, and synaptophysin-immunoreactivity in the rat pituitary gland, and in the related brain regions was investigated. Several groups of TH-immunoreactive neurons were first detected in the brain stem on day E17, and in the hypothalamus on day E18, followed by TH-immunoreactivity in the median eminence and infundibulum on E19–E20. TH-positive fibers appeared in the posterior lobe on day E20 and in the intermediate lobe on day P0. 5-HT-immunoreactivity was first detected on day E17 in neurons and nerve fibers in the brain stem and in the median eminence, respectively. On day E18, a few 5-HT-immunoreactive fibers were detected in the posterior lobe of the pituitary, although they were consistently seen in the infundibulum from day E19. In newborn rats, some 5-HT-immunoreactive fibers, but no neurons, were seen in the hypothalamus. GABA immunoreactivity appeared on day E17 in several nerve fibers of the infundibulum and the posterior lobe. Some neurons in the cortex and ventral hypothalamus transiently expressed GABA immunoreactivity on day E17. In newborn rats, a plexus of GABA-immunoreactive fibers was detected for the first time in the intermediate lobe. No CGRP-immunoreactive fibers could be detected in the prenatal pituitary. On day P10, CGRP-immunoreactive fibers were first observed in the anterior lobe. Later their number considerably increased, while only sporadic fibers could be found in the intermediate or posterior lobes. No substance P-immunoreactivity could be detected in any of the lobes in the embryonic or developing postnatal rat pituitary, instead the adult anterior lobe occasionally showed some substance P-immunoreactive fibers. Synaptophysin-immunoreactivity was first detected in the posterior lobe on day E20, followed shortly by its expression in the intermediate lobe in newborn rats. The time course of GABA and 5-HT expression revealed in the present study suggests that these transmitters, which are initially expressed in the developing pituitary clearly before synaptic maturation, may act as trophic molecules during the prenatal period.     

Pituitary 5-hydroxytryptamine nerves—A possible link with pituitary hormone secretion

Summary A short review of the present knowledge on the innervation of the pituitary gland by 5-hydroxyptramine (5-HT) containing nerves is given.This is followed by results of recent experiments in which the concentrations of 5-HT in different lobes of the rat hypophysis were measured under conditions in which pituitary hormone secretion was increased. A prolonged increase in hormone secretion induced by dehydration and increased sodium chloride intake resulted in a decrease in the 5-HT concentrations in the anterior lobe (AL). The 5-HT content of the neural (NL) and the intermediate lobe (IL) of these rats was hardly changed whereas that of DA was about doubled. Acute stimulation of pituitary hormone secretion by exsanguination under ether anaesthesia also caused a fall in the 5-HT content of the AL. In contrast, in the NL and in the IL of these rats, the 5-HT concentrations were significantly increased. This indicates that the 5-HT system in the AL reacts differently from those in the NL and IL. Pituitary dopamine (DA) contents were not affected by ether and exsanguination. Thus, the pituitary DA and the pituitary 5-HT neuronal systems are activated independently in different endocrine states.The concentrations of 5-HT were also measured in 10 groups of normal male or female rats in the course of 2 years and compared with those of DA. The concentrations of 5-HT were lowest in the AL with little variation between the different groups. In the rest of the tubero-hypophyseal system the concentrations of 5-HT were at least 3, and up to 10 times, higher than in the AL, with larger inter group variations. The DA concentrations in the AL were only 10–20% of those of 5-HT; in the other regions they were equal to or higher than those of 5-HT.     

5-Hydroxytryptamine is synthesized in neurons terminating in the neural and intermediate lobes of the rat pituitary gland

Immunocytochemistry has revealed that nerve fibers within the neural and intermediate lobes of the rat pituitary gland contain 5-hydroxytryptamine (5-HT). Recent anatomical evidence suggests that the content of this amine in the intermediate but not the neural lobe of the pituitary gland may represent 5-HT that has been taken up from the blood rather than synthesized intraneuronally. The purpose of this study was to determine if 5-HT is synthesized in neurons of the neurointermediate lobe of the pituitary gland. 5-HT synthesis was estimated by measuring the accumulation of the 5-HT precursor, 5-hydroxytryptophan (5-HTP), in the neurointermediate lobe of male Long-Evans rats following the administration of NSD 1015, an inhibitor of aromatic L-amino acid decarboxylase. Thirty min following the injection of NSD 1015 (100 mg/kg, i.p.), 5-HTP accumulated in the neurointermediate lobe and the rate of this accumulation was increased by the administration of the 5-HTP precursor, tryptophan, and by electrical stimulation of the pituitary stalk. In addition, repeated injections of the 5-HT uptake inhibitor, fluoxetine (10 mg/kg, i.p., every 12 h for a total of 7 injections), induced a marked depletion of platelet 5-HT but did not alter the concentration of 5-HT in either the neural or intermediate lobes of the pituitary gland. Taken together these results indicate that much of the 5-HT in the neurointermediate lobe of the pituitary gland does not represent 5-HT taken up from the blood, but rather the amine is synthesized in neurons projecting to this region.(ABSTRACT TRUNCATED AT 250 WORDS)     

Innervation of the pituitary gland by supraependymal neurons

Retrograde transport of horseradish peroxidase (HRP) was used to identify supraependymal neurons projecting to the pituitary gland in the hamster. Supraependymal neurons overlying the median eminence were labeled by HRP injections into the neural and intermediate lobes of the pituitary gland; no neurons were labeled following HRP injections confined to the anterior lobe. Supraependymal neurons innervating the pituitary gland may provide a means whereby cerebrospinal fluid-borne substances modulate neuro-intermediate lobe function.     

Dopaminergic neuronal function, anterior pituitary dopamine content, and serum concentrations of prolactin, luteinizing hormone and progesterone in the aged female rat

The serum concentrations of prolactin (PRL), progesterone and luteinizing hormone (LH), and the content and rate of synthesis of dopamine (DA) in selected brain regions were determined in young (3–6 months), intermediate (13–15 months) and aged (24–25 months) female Long-Evans rats. Young rats were examined on the days of diestrus 2 and estrus. Intermediate rats were divided into 2 groups, a group which was cycling regularly (examined on the day of estrus) and a group which exhibited constant estrus. Aged rats were divided into 3 groups one which cycled regularly (examined on day of estrus), one which exhibited constant estrus, and one which exhibited repetitive pseudopregnancies.Serum PRL was increased in all intermediate and aged rats when compared to values in young animals. Serum LH was increased and progesterone decreased in those intermediate and aged rats which exhibited constant estrous reproductive patterns. The DA content was generally decreased in the median eminence, posterior pituitary, striatum, nucleus accumbens and olfactory tubercle of all aged rats, while the rate of DA synthesis was decreased only in the median eminence of aged, non-cycling rats. This suggests that all DA neuronal systems except those in the tuberoinfundibular system are able to compensate for the age-related loss. Despite the apparent reduction of tuberinfundibular DA neuronal function the concentration of DA in the anterior pituitary, which is believed to represent amine released from the neurons, is dramatically increased in intermediate age rats in constant estrus, and in all groups of aged rats. The maintenance of high PRL secretion despite the elevated content of DA in the anterior pituitary suggests in age-related defect in the dynamics of DA in this gland; this defect may contribute to the loss of reproductive function in the aging rat.     

Measurement of 5-hydroxytryptamine synthesis and metabolism in selected discrete regions of the rat brain using high performance liquid chromatography and electrochemical detection: Pharmacological manipulations

High performance liquid chromatography coupled with electrochemical detection (LCEC) was employed to measure 5-hydroxytryptamine (5-HT), 5-hydroxyindole-3-acetic acid (5-HIAA) and 5-hydroxytryptophan (5-HTP) in the suprachiasmatic (SCN), medial preoptic (MPO) and arcuate (AN) nuclei as well as the median eminence (ME) and striatum (ST) of individual rat brains. Biochemical estimations of changes in 5-HT neuronal activity were made by measuring: (1) concentrations of 5-HT and 5-HIAA and (2) the rate of 5-HT synthesis (5-HTP accumulation following the administration of NSD 1015, an inhibitor of aromatic L-amino acid decarboxylase) after the administration of pharmacological agents known to influence these neurons. Pargyline increased the concentration of 5-HT and decreased the concentration of 5-HIAA while probenecid increased the concentration of 5-HIAA in all 5 brain regions. At both 2 and 24 hours after reserpine the concentration of 5-HT decreased, 5-HIAA increased or did not change, and the rate of 5-HT synthesis increased. In most of the brain regions blockers of 5-HT neuronal uptake (fluoxetine, chlorimipramine) did not influence 5-HT or 5-HIAA concentrations dramatically, but increased the rate of 5-HT synthesis. L-tryptophan generally increased the concentrations of 5-HT and 5-HIAA as well as the rate of accumulation of 5-HTP in all regions except the ME where 5-HIAA and 5-HTP concentrations both were unaffected. These results reveal that the method using LCEC is sensitive enough to detect pharmacologically-induced changes in 5-HT metabolism and synthesis in discrete regions of rat brain. The drugs examined in the present study generally caused similar changes in 5-HT dynamics in all 5 brain regions examined.     

Effect of electrical stimulation of the arcuate nucleus on neurochemical estimates of tuberoinfundibular and tuberohypophysial dopaminergic neuronal activities

The activity of nigrostriatal dopaminergic neurons has been estimated biochemically by measuring the rates of dopamine (DA) synthesis (accumulation of dihydroxyphenylalanine (DOPA) after NSD 1015) and turnover (decline of DA concentrations after alpha-methyltyrosine) in the striatum. It has been assumed that the activities of tuberoinfundibular dopaminergic (TIDA) and tuberohypophysial dopaminergic (THDA) neurons can also be estimated by making the same measurements in the terminals of these neurons in the median eminence and the posterior pituitary, respectively. In the present study, this assumption was tested directly by measuring the rates of DA synthesis and turnover in the median eminence and posterior pituitary following electrical stimulation of TIDS and THDA cell bodies in the arcuate nucleus. Electrical stimulation of the arcuate nucleus increased the rate of DOPA accumulation and the alpha-methyltyrosine-induced decline of DA concentrations in the median eminence and in the neural and intermediate lobes of the posterior pituitary. gamma-Butyrolactone (GBL), an anesthetic that selectively inhibits DA impulse flow, reduced the rates of DA synthesis and turnover in the median eminence. GBL also increased prolactin secretion which is tonically inhibited by DA released from TIDA neurons. Serum prolactin levels were significantly decreased by arcuate nucleus stimulation in GBL-anesthetized rats. These results indicate that the rates of DA synthesis and turnover within the median eminence and posterior pituitary reflect the activities of TIDA and THDA neurons, respectively.     

精神分裂症患者的中枢多巴胺和5—羟色胺浓度及其性别差异

目的 了解精神分裂症中枢多巴胺（DA）与5－羟色胺（5－HT）相互作用的变化及其性别影响的程度。方法 应用高效液相色谱对符合CCMD－2精神分裂症诊断标准的30例男性病人、37例女性病人、21例男性对照组、9例女性对照组脑脊液中DA、5－HT及其代谢产物高香草酸（HVA）、5－羟吲哚乙酸（5－HIAA）进行测试,并应用5－HT／DA、5－HIAA／HVA作为它们的相互作用的指标。结果 5－HT／DA、5－HIAA／HVA在4组中有显著性差异（F＝3．567,P＝0．032;F＝12．464,P＝0．001）,进一步分析提示;女性分裂症5－HT／DA显著低于男性对照组,且男性、女性分裂症及男性对照组5－HIAA／HVA均显著低于女性对照组。在男性病例组的相关分析中,5－HT／DA与BPRS及其阳性症状呈显著负漠、非特异性症状呈显著负、正相关;5－HIAA／HVA与思维形式障碍呈显著正相关。结论 精神分裂症患者存在中枢DA和5－HT相互作用的失平衡,这种失平衡与某些重要精神症状有关,且受性别因素的影响。     

Neurotensin-like immunoreactivity and neurotensin receptors in the rat hypothalamus and in the neurointermediate lobe of the pituitary gland

In the rat hypothalamus, cell bodies containing neurotensin-like immunoreactivity were mainly found in the medial preoptic area, the periventricular nucleus, the paraventricular nucleus, the supraoptic nucleus and the arcuate nucleus. [3H]neurotensin binding sites were observed throughout the hypothalamus with a dense accumulation of silver grains over the paraventricular nucleus, the arcuate nucleus and the median eminence region. By radioimmunoassay neurotensin-like immunoreactivity was also found in the neurointermediate lobe of the pituitary gland of various mammalian species and in human postmortem posterior pituitary glands. In the rat studies involving pituitary stalk transections and the neurotoxin monosodium glutamate indicated the presence of a neurotensinergic pathway from the arcuate nucleus to the neurointermediate lobe of the pituitary gland. [3H]neurotensin binding sites were found to be concentrated over the intermediate lobe of the pituitary gland and their presence was not affected by pituitary stalk transection, indicating their localization on endocrine cells of the intermediate lobe of the pituitary gland.     

Topographical dopamine and serotonin distribution and turnover in rat striatum

Topographic distribution of dopamine (DA), serotonin (5-HT), dihydroxyphenylacetic acid (DOPAC), hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) was determined in rat striatum using high-pressure liquid chromatography (HPLC) with electrochemical detection. The ratios of DOPAC:DA and 5-HIAA:5-HT were calculated as indices of turnover of DA and 5-HT. There was a rostro-caudal gradient for both DA and 5-HT, with DA highest in rostral striatum and 5-HT highest in caudal striatum (P less than 0.01). DA concentrations in the coronal plane showed a homogeneous distribution except at the level of the globus pallidus. DOPAC also showed a rostro-caudal gradient and concentrations were significantly increased in the nucleus accumbens (P less than 0.01). DOPAC:DA ratios were significantly increased in both the nucleus accumbens and the ventromedial striatum as compared to the remaining striatal punches. 5-HT was more heterogeneously distributed in the coronal plane with concentrations highest in the ventromedial and the ventrolateral quadrants, where they were 2-3-fold higher than in dorsal striatum (P less than 0.01). Concentrations of 5-HIAA were highest in the nucleus accumbens and ventromedial striatum but HIAA-5-HT ratios were highest in the dorsolateral striatum (P less than 0.01). DA turnover is therefore highest in limbic innervated (n. accumbens and ventromedial) striatum while 5-HT turnover is highest in sensorimotor innervated (dorsolateral) striatum. These findings provide further evidence for functional compartmentalization within the striatum.     

The effect of neurointermediate lobe denervation on hypothalamic neuroendocrine dopaminergic neurons

The contribution of tuberohypophyseal and periventricular-hypophyseal dopaminergic neurons to the regulation of the secretion of prolactin (PRL) has yet to be clarified. In this study, we used pituitary stalk compression to disrupt hypothalamic neural input to the neurointermediate lobe (NIL). Neurointermediate lobe denervation (NIL-D) selectively disrupts the axons of tuberohypophyseal and periventricular-hypophyseal dopaminergic neurons, while leaving tuberoinfundibular dopaminergic neurons and the vascular supply of the pituitary gland intact. NIL-D was performed in ovariectomized (OVX) rats. The concentration of DA and 3,4-dihydroxyphenylacetic acid (DOPAC) in the median eminence (ME) and various regions of the pituitary gland of OVX and OVX+NIL-D rats were measured by HPLC-EC. The concentration of PRL, α-melanocyte stimulating hormone (α-MSH), and luteinizing hormone (LH) in serum were determined by radioimmunoassay. Successful NIL-D was confirmed by increased water intake. One week after NIL-D, serum PRL and α-MSH were elevated, but there was no change in the concentration of LH in serum. The concentration of DA was increased in the median eminence (ME), decreased in the outer zone of the anterior lobe (AL-OZ), as well as the intermediate (IL) and neural lobes (NL), and remained unchanged in the inner zone of the anterior lobe (AL-IZ). The concentration of DOPAC was increased in the ME and NL, decreased in the IL, and remained unchanged in both the AL-IZ and AL-OZ. These data confirm that pituitary stalk compression denervates the NIL. Moreover, decreases in the concentration of DA in the IL and AL-OZ, coupled with elevation of serum PRL and α-MSH indicate that DA from the NIL contributes to the increased inhibition of the secretion of PRL and α-MSH in OVX rats.     

Effects of chronic oral nicotine treatment and its withdrawal on locomotor activity and brain monoamines in mice

The effects of chronic nicotine and its withdrawal on locomotor activity and brain monoamines were studied using a new animal model of administering nicotine in the drinking water to male NMRI mice as the sole source of fluid. Locomotor activity as well as cerebral concentrations of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), noradrenaline (NA) and 3-methoxy-4-hydroxyphenylethyleneglycol (MOPEG) were measured post mortem on the 50th day of nicotine administration or at 12-14 or 23-25 h after withdrawal. On the 50th day of drug administration the chronically nicotine-treated mice were more active than the control mice drinking tap water and after withdrawal from nicotine the locomotor activity dropped to the level of the controls. In chronically nicotine-treated mice the striatal concentrations of DOPAC, HVA and 5-HIAA, hypothalamic 5-HIAA and NA as well as cortical NA were elevated. The concentrations of DOPAC, HVA and 5-HIAA reversed to control levels within 23-25 h after withdrawal from nicotine. The nicotine-induced elevation of the hypothalamic NA concentration was still significant at 23-25 h after withdrawal. At 12-14 h after withdrawal the hypothalamic concentration of MOPEG was increased. In conclusion, our findings on locomotor activity suggest that administration of nicotine in the drinking water to mice for several weeks seems to be a relevant method to study nicotine dependence. Furthermore, the alterations found in cerebral DA, NA and 5-HT metabolism during chronic nicotine administration indicate that all three cerebral transmitter monoamines might be involved in nicotine dependence and withdrawal.     

Brain monoamines in cases with Down's syndrome with and without dementia

Summary Three cases of Down's syndrome, one of which had a clinical history of a presenile dementia during final years, were analyzed for the content of tyrosine (Tyr), dopamine (DA), noradrenaline (NA), tryptophan (Try), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in the following regions: the caudate nucleus, the putamen, the thalamus, the mesencephalon, and the hippocampus. A rather generalized reduction of DA, NA, 5-HT, and 5-HIAA was noted in the demented DS case.     

Brain monoaminergic and neuropeptidergic variations in human aging

Summary The effect of age on the monoamines 5-hydroxytryptamine (5-HT), noradrenaline (NA) and dopamine (DA), their metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), 3,4-dihydr-oxyphenylacetic acid (DOPAC), and the 5-HT precursor 5-hydroxy-L-tryptophan (5-HTP), together with the peptides neuropeptide Y (NPY), somatostatin (SOM), and corticotropin-releasing factor (CRF), was studied in frontal cortex, gyrus cinguli and hypothalamus from 23 healthy control subjects, aged 16–75 years. After correcting for postmortem interval, significant decreases in gyrus cinguli NA, NPY and CRF, and hypothalamic DA, HVA, and 5-HIAA concentrations were obtained with advancing age. The involvement of the monoaminergic system in several functional abnormalities appearing in senescence is suggested. Furthermore, evidence is given of the participation of the peptidergic systems in the aging process.     

Determination of the source of 5-hydroxytryptaminergic neuronal projections to the neural and intermediate lobes of the rat pituitary gland through the use of electrical stimulation and lesioning experiments

5-Hydroxytryptamine (5-HT)-containing axons and terminals have been visualized in the neural and intermediate lobes of the rat pituitary gland, but the origin of these fibers remains in question. This study was designed to determine if 5-HT cell bodies in the brainstem or in the dorsomedial nucleus of the hypothalamus project to either of these pituitary lobes. Since lesions and electrical stimulation of 5-HT cell bodies decrease and increase, respectively, the rate of 5-HT synthesis in regions innervated by these cells, these techniques were employed. The in vivo rate of 5-HT synthesis was determined by quantifying the rate of accumulation of the 5-HT precursor, 5-hydroxytryptophan (5-HTP), in the neural and intermediate lobes of the pituitary gland 30 min after the administration of a decarboxylase inhibitor (NSD 1015, 100 mg/kg, i.p.). The application of 30 min of stimulating current (monophasic cathodal pulses of 1 ms duration and 0.3 mA current delivered at a frequency of 10 Hz) to electrodes implanted in the dorsal and median raphe nuclei increased the rate of 5-HT synthesis in both the neural and intermediate lobes of the pituitary gland. 5,7-Dihydroxytryptamine lesions of these nuclei altered neither 5-HTP accumulation nor 5-HT concentrations in the neural and intermediate lobes, but similar lesions of the nuclei raphe pontis and raphe magnus decreased both the concentration of 5-HT and the accumulation of 5-HTP in these pituitary regions.(ABSTRACT TRUNCATED AT 250 WORDS)