Diego Lipari

The hypothalamic magnocellular neurosecretory system in developing rats

Studies concerning the development of the magnocellular system are scarce and discordant in literature. We carried out an immunohistochemical study on supraotic and paraventricular hypothalamic nuclei using antivasopressin and antioxytocin antibodies in developing rats between the 15th day of intrauterine life and the 6th day of postnatal life. In addition, we performed RT-PCR experiments to establish the stage at which these hormones appear and neurosecretory activity commences. The results showed that supraoptic and paraventricular nuclei appear, respectively, on the 16th and the 18th day of intrauterine life and both immediately synthetize vasopressin neurohormone. By contrast, synthesis of oxytocin takes place from the 2nd day after birth. Probably, these nuclei synthetize oxytocin in conjunction with the decline of placental maternal oxytocin.

Presence of atrial natriuretic factor in normal and hyperplastic human prostate and its relationship with oxytocin localisation

In this work, we showed the presence of atrial natriuretic factor (ANF) in human prostate and compared its localisation in normal and hyperplastic conditions. ANF was localised in epithelial and stromal cells, being increased in hyperplasia, mainly in the stromal component. Moreover, we compared ANF and oxytocin positivity in the same glands, focusing on the possible relationship between the paracrine effects of these two hormones.

Atrial natriuretic peptide secretion during development of the rat supraoptic nucleus

Since a relationship between atrial natriuretic peptide and oxytocin was recently demonstrated in the heart (Gutkowska et al., 1997), the aim of this study was to determine whether a relationship between the two peptides is present also in the rat hypothalamus. For this purpose, we measured ANP-ontogeny in the rat hypothalamus immunohistochemically and compared it with oxytocin-ontogeny which we previously studied. The results showed that the ANP-peptide and mRNA-ANP start at the 18th day of the fetal life. Our earlier data for oxytocin in the rat hypothalamus showed that only mRNA-oxytocin appeared the 18th day of foetal life (Farina Lipari et al., 2001); thus, at the 18th day of foetal life, mRNA-ANP, ANP-peptide and mRNA-oxytocin are present. We conclude that in the hypothalamus, differently from that in the heart, ANP might play a role on the synthesis of the oxytocin since ANP and its mRNA appear earlier than oxytocin.

Modifications of atrial natriuretic peptide and vasopressin peptides in the rat hypothalamic supraoptic nucleus during resistance training

Many studies have demonstrated the involvement of atrial natriuretic peptide (ANP) and vasopressin (VP) in the homeostasis of body fluids, but few studies have regarded the hypothalamic magnocellular neurosecretory system during physical exercises. The aim of the present immunohistochemical work is to study the activity of ANP and VP secreting neurons of the hypothalamic supraoptic nucleus during and after resistance training. The study was carried out in Wistar rats trained by a physical resistance-type exercise, using a rung ladder and a varying load fastened to the tail of each rat; the exercise lasted 20 min everyday for periods of 15, 30 and 45 days. Animal groups were sacrificed at the end of each training period and one group was sacrificed after 60 days from the beginning of training, i.e.15 days after completing a 45 day training. The results show that ANP and VP-immunopositivity is at first lesser in the trained rats than in the corresponding controls and then increases from the 15th to the 45th day of training; the increase of the immunopositivity in the trained rats indicates a decreased degranulation of the neurons. The comparison between VP and ANP-immunopositivity suggests that in the early phase of training VP-release in the bloodstream is higher than ANP-release, therefore the antidiuretic action of VP is expected to prevail on ANP action and an electrolyte unbalance may occur.

ANP(Atrial natriuretic peptide) presence in the heart of a tunicate, Ciona intestinalis

Atrial natriuretic peptide was found in the heart of vertebrates, we studied the ANP presence in the heart of Ciona intestinalis. This is animal is very important because of the its evolutionary position between invertebrates and vertebrates. ANP presence was only revealed in myoepithelial cells of the myocardium. Results suggest the hypothesis that ANP is present not only in the vertebrates but also in the invertebrates and in Ciona heart ANP might play a similar role like in the heart of vertebrates.

Cordon ombilical. Nouvelles sur l’acétylcholine

Introduction L’acetylcholine (Ach) fut la premiere substance impliquee dans la transmission synaptique. Elle est synthetisee a partir de l’enzyme acetyl-choline transferase (ChAT) et est degradee par l’acetyl-choline esterase (AchE). Il existe des anticorps specifiques diriges contre la ChAT et l’AchE qui ont permis de mettre en evidence la distribution de ce neurotransmetteur au niveau des systemes nerveux central et peripherique. Il faut rappeler que les neurones somato-moteurs, pre-ganglionnaires du tronc cerebral et de la moelle epiniere, les neurones post-ganglionnaires visceraux des ganglions parasympathiques et de quelques ganglions orthosympathiques sont cholinergiques. Ces donnees montrent comme l’Ach est impliquee dans la regulation neuronale de l’hemoreologie cerebrale ainsi que dans d’autres regions jusqu’a la microcirculation. Il est interessant de reprendre le vieux probleme de la presence de l’Ach dans le cordon ombilical ou, a differentes reprises, la mediation cholinergique a ete confirmee ou niee. Materiels et Methodes Des fragments de cordon ombilical humain en fin de grossesse ont ete fixes en solution de Bouin alcoolique pour une preparation histologique ; d’autres fragments ont ete fixes dans du liquide de Karnowsky pour mettre en evidence les activites ChAT et AchE (Martinez-Rodriguez E et al, Trab. Inst. Cajal Invest. Biol., 56 ; 27 : 1964 ; Sakamoto T et al., Nip. San. Fuj. Gak. Zas., 1996). Resultats Le probleme de la mediation du cordon ombilical est plein d’interrogations. La presence de la ChAT et de l’AchE dans le sarcoplasme des parois vasculaires est demontrable par methode histochimique dans la veine et les deux arteres du cordon ombilical. Ceci suggere que ces enzymes jouent un role dans la contraction myogenique. Ces donnees sont a mettre en relation avec d’autres signaux qui provoquent la contraction tels la NOS.