Hypothalamic regulation of histidyl-proline diketopiperazine binding sites in the rat liver

The effects of hypothalamic hormones and electrolytic lesioning of the ventromedial hypothalamic nuclei (VMH) on histidyl-proline diketopiperazine (cyclo(His-Pro] binding in the rat liver were studied. VMH-lesioning markedly decreased cyclo(His-Pro) binding in the liver. Scatchard analysis revealed that the loss of cyclo(His-Pro) binding induced by VMH lesioning was due to a decrease in the number and affinity of binding sites. Somatostatin (SS) administration decreased cyclo(His-Pro) binding. The SS-induced changes in cyclo(His-Pro) binding were due to changes in the binding affinity. On the other hand, the administration of TRH or LH-RH did not affect cyclo(His-Pro) binding in the liver, although cyclo(His-Pro) has been proposed to be a metabolite of TRH. These findings suggest that the hypothalamus may regulate the cyclo(His-Pro) binding sites in the liver probably by controlling pancreatic SS secretion, since a VMH-lesion is reported to cause hypersecretion of pancreatic SS.     

Multiple neurinoma of the spinal cord: case report

The patient, a 72-year-old female, was admitted with an 11-year history of progressive dysesthesia in the left leg. Neurological findings on admission revealed weakness in the bilateral legs, hyperreflexia of left leg, hypalgesia and hypesthesia under the Th 8 level, and urinary incontinence. Plain lumber X-ray showed enlargement of the intervertebral foramen of L 1/2. Myelography disclosed block age at the level of Th 9 and filling defect at the level of Th 10/11 and L1/2. CT myelography revealed a cord swelling and partially exophytic tumor from Th 8 to Th 9, another tumor located posterior-laterally at the level of Th 11, and another tumor located extra and intradural at the level of L1/2. Laminectomy was performed from Th 8 to L 3. A tumor of the Th 9 was located intramedullary, another tumor of the Th 11 was located intradural extramedullary, and another tumor of the L1/2 was located in the epidural space (so-called dumb-bell type tumor). These tumors were removed completely except the extra-canal part of L1/2 tumor. Histopathological examination revealed typical Antoni type A schwannoma in all tumors. This case was considered multiple neurinomas of the spine in which tumors were located in three separate anatomical sites, intramedullary, intradural extramedullary, and epidural sites. This patient did not show café-au-lait spot, and neurofibroma in her body. The authors considered the patient might be a case of central neurofibromatosis. The authors stressed that multiple neurinomas of the spine is not rare, so careful study of the whole spine is necessary including its intramedullar space.     

Neurofibromatosis associated with retinoblastoma: case report.

A case of neurofibromatosis is presented in a 3-year-old male with leucokoria in his left eye. Enucleation was performed, and on pathological examination the mass filling the globe proved to be retinoblastoma. We believe ours to be the first reported case of this rare association.     

A novel cognition enhancer NS-105 modulates adenylate cyclase activity through metabotropic glutamate receptors in primary neuronal culture

The effect of (+)-5-oxo-D-prolinepiperidinamide monohydrate (NS-105), a novel cognition enhancer, on adenylate cyclase activity was investigated in cultured neurons of the mouse cerebral cortex. NS-105 (10^–7 and 10^–6 M) inhibited forskolin-stimulated cyclic AMP formation, an action that was dependent on pertussis toxin-sensitive G proteins. Conversely, in pertussis toxin-pretreated neurons, NS-105 (10^–7 –10^–5 M) significantly enhanced the forskolin-stimulated cyclic AMP formation, and this action was completely reversed by cholera toxin. A metabotropic glutamate receptor agonist (1S, 3R)-1-aminocyclopentane-1, 3-dicarboxylic acid (1S, 3R-ACPD) produced similar bi-directional actions on the cyclic AMP formation. Both of these inhibitory and facilitatory actions of NS-105 and 1S, 3R-ACPD were blocked by L(+)-2-amino-3-phosphopropinoic acid (L-AP3). NS-105 (10^–6 M) and 1S, 3R-ACPD (10^–4 M) significantly enhanced isoproterenol- and adenosine-stimulated cyclic AMP formation. The enhancement of such Gs-coupled receptor agonists-stimulated cyclic AMP formation was also produced by quisqualate but not by L(+)-2-amino-4-phosphonobutanoate (L-AP4). The phosphoinositides hydrolysis was enhanced by 1S, 3R-ACPD (10^–4 M) but not by NS-105 (10^–6 M), however, 1S, 3R-ACPD-induced increase in phosphoinositides turnover was attenuated by NS-105. These findings suggest that NS-105 stimulates metabotropic glutamate receptor subclasses that are coupled both negatively and positively to adenylate cyclase, but it acts as an antagonist at the receptor subclasses that are linked to phosphoinositides hydrolysis. Received: 3 February 1997 / Accepted: 25 April 1997