We have previously demonstrated that acute third ventricle injections of both Pb 2+ and Cd 2+ impair the dipsogenic response elicited by three different situations: dehydration and central cholinergic or angiotensinergic stimulation. ß-Adrenergic activation is part of the multifactorial integrated systems operating in drinking behavior control in the central nervous system. In the present study acute third ventricle injections of Pb 2+ (3, 30 and 300 pmol/rat) or Cd 2+ (0.3, 3 and 30 pmol/ rat) blocked the dipsogenic response induced by third ventricle injections of isoproterenol (ISO; 160 nmol/rat) in a dose-dependent manner. Normohydrated animals receiving ISO + NaAc (sodium acetate) or saline (controls) displayed a high water intake after 120 min (ISO + saline = 5.78 ± 0.54 ml/100 g; ISO + NaAc = 6.00 ± 0.6 ml/100 g). After the same period, animals receiving ISO but pretreated with PbAc at the highest dose employed (300 pmol/rat) drank 0.78 ± 0.23 ml/100 g while those receiving ISO and pretreated with the highest dose of CdCl 2 (30 pmol/rat) presented a water intake of 0.7 ± 0.30 ml/100 g. Third ventricle injections of CdCl 2 (3 nmol/rat) or PbAc (3 nmol/rat) did not modify food intake in rats deprived of food for 24 h. Thus, general central nervous system depression explaining the antidipsogenic action of the metals can be safely excluded. It is concluded that both Pb 2+ and Cd 2+ inhibit water intake induced by central ß-adrenergic stimulation. Received April 11, 1996 Accepted December 17, 1996 Key wordsHuman exposure to heavy metals such as cadmium (Cd 2+ ) and lead (Pb 2+ ) may bring about several adverse reactions. Neurotoxicity induced by heavy metals is well-documented in humans and experimental animals (1). Both Cd 2+ and Pb 2+ reach the central nervous system either by crossing the bloodbrain barrier or via retrograde axonal transport (2,3).The presence of heavy metals in the central nervous system disrupts the functional integrity of several neurotransmitter pathways. Many independent reports confirm alterations in brain monoaminergic receptors and uptake after Pb 2+ (4) and Cd 2+ (5,6) intoxication.We have recently used a new approach to study the acute actions of heavy metals on
Vanilla is the most well-known and economically important genus of Orchidaceae in the world. Vanilla bahiana is restricted to Brazil and its conservation status was recently assessed as ‘Endangered’. The species is phylogenetically closely related to V. planifolia, whose pods are the main natural source of vanillin. The primary desirable traits for vanilla production are high fruit set and great resistance to abiotic stress. High temperatures (> 32ºC) and heavy rain favor fungal infection, and thus are indirectly responsible for fruit drop by V. planifolia in cultivation. The aim of the present study was to follow the process of pod ripening of V. bahiana in a restinga fragment in an Environmental Protection Area of Bahia State, and to highlight implications for vanilla crop improvement. Fieldwork was carried out from April 2016 to January 2017. A total of nine manual self-pollinations and nine manual cross-pollinations were successfully carried out. Fruit length, diameter and girth were recorded every two weeks. Fruit permanence in the infrutescence was measured as consecutive days from pollination. Descriptive statistics were calculated and Pearson correlation analysis performed among all attributes per pollination method. The influence of temperature and rainfall was also analyzed. Pod measurements and fruit permanence in the infrutescence were higher for cross-pollination than self-pollination. Higher rainfall results in fruit drop. The use of V. bahiana in breeding efforts for the genus is here strongly suggested and supported by previously published studies that allowed us to highlight several desirable traits: vanillin production, its wide geographical distribution and occurrence in a variety of habitats; substantial populations; resistance to conditions of drought and high luminosity and temperature; extensive blooming period; high number of flowers per raceme; possible synchronised flowering with V. planifolia, and fruiting throughout the year. These prospects are promising and should be further evaluated, not only for V. bahiana but for other vanilla crop wild relatives. Studies of pollination ecology can be used to set guidelines for the conservation of the V. planifolia group and to encourage the development of strategies to increase the production of fruit and, consequently, vanillin for its culinary uses and medical applications.
We have previously demonstrated that acute third ventricle injections of both lead and cadmium prevent the dipsogenic response elicited by dehydration or by central injections of dipsogenic agents such as angiotensin II, carbachol and isoproterenol in rats. We have also shown that the antidipsogenic action of cadmium may be due, at least in part, to activation of thirst-inhibitory central serotonergic pathways. In the present paper we show that in Wistar male rats the antidipsogenic effect of both lead acetate (3.0 nmol/rat) and cadmium chloride (3.0 nmol/rat) may be partially dependent on the activation of brain opiatergic pathways since central injections of naloxone (82.5 nmol/ rat), a non-selective opioid antagonist, blunt the thirst-inhibiting effect of these metals. One hundred and twenty minutes after the second third ventricle injections, dehydrated animals (14 h overnight) receiving saline + sodium acetate displayed a high water intake (7.90 ± 0.47 ml/100 g body weight) whereas animals receiving saline + lead acetate drank 3.24 ± 0.47 ml/100 g body weight. Animals receiving naloxone + lead acetate drank 6.94 ± 0.60 ml/100 g body weight. Animals receiving saline + saline drank 8.16 ± 0.66 ml/100 g body weight whilst animals receiving saline + cadmium chloride drank 1.63 ± 0.37 ml/100 g body weight. Animals receiving naloxone + cadmium chloride drank 8.01 ± 0.94 ml/100 g body weight. It is suggested that acute third ventricle injections of both lead and cadmium exert their antidipsogenic effect by activating thirst-inhibiting opioid pathways in the brain.
Correspondence
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.