Sex differences in dopaminergic neurons of substantia nigra pars compacta of adult and aged rats: a histological and immunohistochemical study

Substantia nigra pars compacta [SNC] is the main source of dopaminergic [DA] input to the striatum. Parkinson's disease is a neurodegenerative disease affecting DA neurons in SNC, with a higher incidence in men. To study the effect of sex on the structure of DA neurons in adult and aged rat SNC. The brains of 22 adult [11 males and 11 females] and 22 aged [11 males and 11 females] albino rats were processed for histological and immunohistochemical examination of DA neurons in the right SNC. Golgi-Cox staining of adult male SNC neurons showed more varicosities and less extension of their dendrites than adult female SNC. Adult male SNC showed a nonsignificant increase in tyrosine hydroxylase-positive neurons than adult female SNC. Aging-related changes were more marked in aged male rats. Aged SNC showed decreased packing density of neurons, some of which appeared irregular and deeply stained. A reduction in Nissl staining was observed. Golgi-Cox staining showed a marked decrease in extension and branching of the dendrites with loss of spines. Ultrastructurally, accumulation of lipofuscin pigment, membranous whorls, dilated Golgi bodies, decreased rough endoplasmic reticulum, and destroyed cristae of mitochondria were observed. A significant reduction in tyrosine hydroxylase-positive neurons was evident in aged SNC. Sex differences in DA neurons of SNC were more apparent in aged rats, with more degenerative changes in the aged male group, which may underlie the predisposition of males to Parkinson's disease

Influence of isotretinoin treatment on monoamines in different brain areas of male rats

Despite widespread use of isotretinoin for its anti-acne effects and its current evaluation in clinical trials as a cancer treatment, little is known about its effect on brain function and neuronal pathways in adult animals, particularly after oral administration which mimics the human route. Here, adult male rats were gavaged daily with olive oil and 1.5mg/kg/day isotretinoin for 4 weeks during which body weight was measured and changes in food intake and locomotor activity were observed. After decapitation, the concentrations of dopamine [DA], norepinephrine [NE], serotonin [5-HT] and 5-hydroxyindoleacetic acid [5-HIAA] were measured in different brain areas of rats after 2 and 4 weeks of repeated injection. The results show that, following isotretinoin administration body weight, food intake and locomotor activity were generally decreased. Treatment with isotretinoin produced marked increases in the concentrations of DA and 5-HIAA after 2 and 4 weeks and of NE after 4 weeks in the various brain regions examined. However, level of 5-HT was significantly decreased in most of the brain areas studied after 2 and 4 weeks following isotretinoin treatment. The results also show that all of these effects induced by isotretinoin treatment were tended to resolve within one week of drug cessation. It is possible to conclude that such alteration in monoamine systems could contribute to the isotretinoin induced increase in depression related behavior

Effect of sildenafil (Viagra®) on the genital reflexes of paradoxical sleep-deprived male rats

Since there is evidence that paradoxical sleep deprivation (PSD) elicits penile erection (PE) and ejaculation (EJ), and that the erectile response of rats is mediated by nitric oxide, the present study sought to extend the latter finding by assessing the effects of sildenafil on the genital reflexes of male Wistar rats subjected to PSD. We also determined the influence of sildenafil on hormone concentrations. In the first experiment, sildenafil at doses ranging from 0.08 to 0.32 mg/kg was administered intraperitoneally to rats that had been deprived of sleep for 4 days and to home cage controls (N = 8-10/group). The frequency of PE and EJ was measured for 60 min. PSD alone induced PE in 50 percent of the animals; however, a single injection of sildenafil did not significantly increase the percentage of rats displaying PE compared to PSD-saline or to home cage groups. PSD alone also induced spontaneous EJ, but this response was not potentiated by sildenafil in the dose range tested. Testosterone concentrations were significantly lower in PSD rats (137 ± 22 ng/dL) than in controls (365 ± 38 ng/dL), whereas progesterone (0.9 ± 0.1 vs 5.4 ± 1 ng/mL) and plasma dopamine (103.4 ± 30 vs 262.6 ± 77 pg/mL) increased. These changes did not occur after sildenafil treatment. The data show that although sildenafil did not alter the frequency of genital reflexes, it antagonized hormonal (testosterone and progesterone) and plasma dopamine changes induced by PSD. The stimulation of the genital reflexes by sildenafil did not result in potentiating effects in PSD rats.

Influence of dietary omega-3 and omega-6 containing oils on the neurobehavioral responses in male rats

Omega-3 and Omega-6 fatty acids affect growth vitality and mental state. They favorably affect atheroscieorosis, coronary heart diseases, inflammatory diseases and perhaps even behavioral disorders. The aim of the present study was to elucidate the possible effect of feeding rats a diet enriched with 5% of each flaxseed oil or sun flower oil [for 10 weeks]on the levels of brain monoamines and on the parameters of two behavioral tests[open field and swimming tests].90 male rats pups after weaning[21 days of age]were divided into 3 groups: group[1]control untreated, group [2] and [3] subjected to a diet containing [5% flaxseed oil or sun flower oil] respectively for 10 weeks. The results showed that both Omega-3 and 6 produced a significant increase in the levels of serotonin and dopamine. In the open field test omega-3 and omega-6 oils induced a significant increase in the grooming number whereas, induced a significant decrease in the rearing number. Application of swimming test to tested groups revealed that both Omega-3 and Omega-6 induced a significant decrease in latency time, The data showed that both Omega-3 and Omega-6 containing oils cause alterations In the brain functions and behavior in rats

Effect of simulated ascent to 3500 meter on neuro-endocrine functions.

Ascent to extreme High Altitude (HA) is in steps and it entails acclimatization at moderately HA locations. In terms of acclimatization, it is pertinent to understand the physiological changes, which occur on immediate ascent to moderate HA. The study aimed to evaluate the effect of ascent to 3500 m on neuro-endocrine responses in the first hour of induction. The plasma levels of catecholamines and cortisol were measured before and after one hour of ascent to high altitude. The peripheral oxygen saturation (SpO2), Galvanic Skin Resistance (GSR), Heart Rate (HR) and Blood Pressure (BP) were simultaneously monitored. The plasma epinephrine, norepinephrine, dopamine and cortisol were increased after one-hour exposure to 3500 m altitude as compared to before exposure. The SpO2 showed a significant decrease during and after high altitude induction. The heart rate and diastolic BP increased at 3500 m whereas the GSR did not show significant changes. There are changes in neuroendocrine responses, which reflect a sympathetic over activity in the first hour of exposure to 3500 m.

Altered dopamine levels induced by the parasite Profilicollis antarcticus on its intermediate host, the crab Hemigrapsus crenulatus

A serotonergic pathway is apparently involved in parasite-host interactions. Previous studies conducted in our laboratory showed increased rates in oxygen consumption and alterations in body posture in the crab Hemigrapsus crenulatus parasitized by the acanthocephalan, Profilicollis antarcticus. Such changes may be related to the functions described for biogenic amines in crustaceans. During the infective stage the acanthocephalans live freely in the hemocelomic cavity, suggesting that the possible alteration induced by biogenic amines may be related to their neurohormonal function in crustaceans. To test whether the presence of P. antarcticus produced neurohormonal changes in its intermediate host, H. crenulatus, we analyzed serotonin and dopamine levels in the host using HPLC with electrochemical detection. Two groups of 11 female crabs were studied; one group was artificially inoculated with two cystacanths while the other was used as the control. Our results show a dramatic increase in hemolymph dopamine, but not serotonin in H. crenulatus parasitized by the acanthocephalan P. antarcticus. Our results, along with those reported by Maynard (1996), suggest a parasite-specific strategy involved in the behavior alteration caused by the acanthocephalans on their intermediate host. The use of a biogenic amine as a mechanism of interaction by the parasites gives them an endless number of alternative potential actions on their intermediate hosts.

Dopamine: pharmacologic and therapeutical aspects / Dopamina: aspectos farmacologicos y terapeuticos

Dopamine is a biogenic amine synthesized in the hypothalamus, in the arcuato and caudate nuclei and in several areas of the central peripheral nervous system. It has been widely established that dopamine and its agonists play an important role in cardiovascular, renal hormonal and central nervous system regulation through stimulation of alpha and beta adrenergic and dopaminergic receptors. There are several agonists of DA2 dopaminergic receptors such as: bromocriotine, pergolide, lisuride, quinpirole, and carmoxirole, which inhibit nerepinephrine release, and produces a decrease of arterial blood pressure and, in some cases, bromocriptine and pergolide reduce heart rate. From a therapeutical point of view, the abone mentined agonists are used for treatment od Parkinson's disease, acting on DA2 dopaminergic receptors of the nigrostriatal system. Bromocriptine and the other domaminergic agonists mentioned act on DA2 receptor of the tuberoinfundibular system inhibiting prolactin release, decreasing hyperprolactinemia and tumor size. Among DA1 receptor agonists we can mention: fenoldopan, pirebedil, ibopamine, SKF 3893, apomorphine (non specific). Activation of these receptors decreases peripheral resistance and reduces arterial blood pressure, increases heart rate and sympathetic tone and the renin aldosterone system activity. Among DA2 receptor antagonists we can mention: metoclopramide, domperidone, sulpiride and haloperidol. From a therapeutic point of view, metoclopramide and domperidone are used in gastric motility disorders and haloperidol in psychotic alterations. Antagonists of DA1 receptors are: SCH23390 and clozapine. Clozapine is used for traating schizophrenia

Separación de aminas biogénicas mediante cromatografía líquida de alta resolución / High-performance liquid chromatographic determination of biogenic amines

En este trabajo se han compilado los distintos modos cromatográficos y sistemas de detección utilizados en la cromatografía líquida de alta resolución de aminas biogénicas. Se indican las características generales del intercambio catiónico, fase reversa, fase reversa de pares iónicos y cromatografía de partición con fase reversa de pares iónicos. También se analizan comparativamente la detección UV, detección fluorimétrica usando fluorescencia nativa o bien derivatización pre- y postcolumna y detección electroquímica de gran utilidad para esta extensa familia de compuestos. Se dan ejemplos de aplicación de interés en el campo bioquímico-clínico, con el análisis de ácido homovainillínico, ácido 3,4-dihidroxifenilacético y ácido 5-hidroxiindolacético en líquido cefalorraquídeo, metanefrinas, ácido 3,4-dihidroxifenilacético, catecolaminas, ácidos urinarios y 3-metoxi-4-hidroxifenilglicol en orina, catecolaminas y 3-metoxi-4-hidroxifenilglicol en plasma, catecolaminas, 3-metoxi-4-hidroxifenilglicol y otros neurotransmisores en cerebro de rata. Se discuten, también, los tratamientos previos requeridos especialmente para orina y plasma, así como las condiciones de conservación y su incidencia en los resultados obtenidos