Browsing by Subject "Neurotensin"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    Open Access
    Different effects of neurotensin and neuromedin-N on the proliferative activity of rat adrenal cortex
    (Murcia : F. Hernández, 1994) Markowska, A.; Nussdorfer, G.G.; Malendowicz, L.K.
    Evidence indicates that neurotensin (NT) and neuromedin-N (NMN) exerts an adrenocorticotropic effect in the rat. The present study aimed to investigate whether these neuropeptides are able to stimulate the proliferation of rat adrenocortical cells in vivo and to compare their mode of action. Adrenocortical proliferative activity was assessed by the metaphasearrest technique and metaphases were counted per medulla-containing adrenal section. A bolus administration of NT (3 pglrat) resulted in a significant increase in the number of metaphases in both zona fasciculata and the entire cortex, an effect observed 48 h after the in.jection. The administration of NMN (3 yglrat) induced a notable rise in the number of metaphases in the zona fasciculata and the entire cortex within 12 h, followed by a subsequent drop after 24 h and a return to normal values at 48 h. These findings indicate that NT and NMN enhance rat adrenal growth in vivo acting via different mediators.
  • Thumbnail Image
    Publication
    Open Access
    Effects of neurotensin and bombesin on the secretory and proliferative activity of regenerating rat adrenal cortex
    (Murcia : F. Hernández, 1999) Hochol, A.; Markowska, A.; Meneghelli, V.; Jedrzejczak, N.; Majchrzak, M.; Nowak, M.; Nussdorfer, G.G.; Malendowicz, L.K.
    Neurotensin (NT) and bombesin (BM)-like peptides are known to be involved in the regulation of the rat hypothalamo-pituitary-adrenal axis. By using selective NT- and BM-receptor antagonists (NT-A and BM-A, respectively) we investigated whether endogenous NT and BM-like peptides play a role in the control of rat adrenal secretion and growth during enucleation-induced regeneration. At day 5 of regeneration, NT-A did not affect the plasma concentrations of aldosterone (PAC) and corticosterone (PBC), but at day 8, it raised both PAC and PBC over the respective baseline value; the simultaneous administration of NT abolished this effect of NT-A. BMA did not alter PAC and PBC at day 5 of regeneration, while at day 8 it enhanced PBC, an effect reversed by BM. NT-A did not alter mitotic index, and BM-A lowered it at both day 5 and day 8 of regeneration, an effect suppressed by the simultaneous administration of BM. Collectively, these findings allow us to draw the following conclusions: 1) endogenous NT and BM-like peptides influence adrenocortical regeneration in rats; 2) NT exerts a tonic inhibitory action on both aldosterone and corticosterone secretion, without affecting cellproliferation rate; and 3) BM-like peptides exert a tonic suppressive effect on corticosterone production, coupled with a clear-cut stimulating effect on cell proliferation.
  • Thumbnail Image
    Publication
    Open Access
    Studies on the involvement Histology and Histopathology Cellular and Molecular Biology of endogenous neuropeptides in the control of thymocyte proliferation in the rat
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2001) Trejter, M.; Warchol, J. B.; de Caro, R.; Brelinska, R.; Nussdorfer, G. G.; Malendowicz, L. K.
    The possible involvement of endogenous vasoactive intestinal peptide (VIP), cholecystokinin (CCK) and neurotensin (NT) in the control of thymocyte proliferation ha s been investigated in vivo in the immature rat. For this task, we have studied the effects of the administration of selective antagonists of the receptors of the three neuropeptides on the mitotic index (%0 of metaphase-arrested cells after vincristin injection) of thymocytes. Both CCK- and TN-receptor antagonists were ineffective. In contrast, two VIP receptor antago nists (VIP-As) enhanced the mitotic index of thymocytes. VIP reversed the effect of VIP-As, but when administered alone it did not alter the mitotic activity of thymocytes. In light of these findings, we conclude that endogenous VIP exerts a maximal tonic inhibitory influence on the basal proliferative activity of rat thymocytes, while endogenous CCK and NT do not play a relevant modulatory role in thi process.