Document k9o43jYV7rmjZV845NBbnq6aB

c/t V Fxpcncnlin 35 (1979), Birkhauser Vcrlag, Basel (Schweiz) the mode of action of substances causing neuronal depolar ization. For inslancc, ouabaine, an inhibitor of Na+-K4ATPase" in conlrasl (o MDP, did not cause any shape change in plaicleis. This indicates that (he MBP-induced shape change cannot be due lo inhibition of Na+-K+ATPase, and that the depolarizing effects of ouabaine* and of MBP in neuronal cells may well have different natures. Platelets might also be used to screen for substances able to antagonize the effects of MBP on membranes, which would be of potential intcrcsl for dcmyclinaling diseases e.g. multiple sclerosis. In these disorders proteins seem to be liberated from the myelin sheaths, whose content of MBP, but not of histones, is quite high1' Indeed, increased amounts of MBP-like material have been found in the cerebrospinal fluid of patients with demyclinating disor ders20 22 If these proteins were to act on neuronal mem branes this might cause neurological manifestations e.g, during episodes of acute exacerbation of the disease. Final ly, it may be of interest to investigate whether there is a difference between platelets of patients with demyelinaling disorders and those from healthy controls in their reaction to MBP. 1 Acknowledgment. We thank Miss B. Gieux and Miss M. Hatidschin for skilful technical assistance. 2 M. Graf and A. Fleischer, Br. J .Pharmac.,in press (1979). 3 M. Graf, A. Laubsclier, J.G. Richards and A. Fleischer, J.clin. l.ab. Invest., in press (1979). loro F. Michal and G. Bom, Naiure 2.;/. 220 (1971) G.F.. Deiblcr, RE. Marlenson and M W Kirs prr,, n.,t chem.2, 139(1972). p P R. Dunkicy and P^R. Carnegie, in: R ,,mh Methods ,n Neurochenustry, vol.3. p.219. Ed. N. Mar,, and R. Kodmal," Plenum Press. New York 1974. * 52^1^(1977) P ^ Borgerding and D. L. CraP). Slain 7. _hm.l 8 H. J. Weiss, New Engl. J. Med 2PJ. 531 (1975) 9 BT3^)Gahwiler 0,,d c.G- Honegger. Neurosci. l.eti. II. 317 10 C.G. Honegger, B.H. Gahwiler and H. Klcr, Neuroses Lett 4 303 (1977). ' 11 K.A. GrflUurt.lKiromb Diath. haemorrh. 21. 450 (1969). 12 C S P. Jankins, M.A. I', - kliain, R.L. Kinlough-Rathbrmc and J.F. Mustard, Bldtod 37. 395 (1971). 13 J.G. White, Am. J. Path. (W?. 447 (1972). 14 H.J Ryser, Science 139. 390(1968). 15 R. T. T.adlcy and C. Trachtenberg Brain Res. /5. I (1978) 16 Y. 7 ietomi and A. Kuramoto, i rombos, Hacmostas ] I (19V ,. ' 17 P. Massini, L. C. Metcalf, U. Nttf and E. F. I.Uscher Haemos tasis 3, 8(1974). 18 J.L. Moake, K. Ahmed. N.R. Bacbur and 13 E. Gutfrcund, Biochim. biophys. Acta 211. 337 (1970). 19 PE. Braun and S.W. Brostoff, in: Myelin, p 201. Ld P. Moreli. Plenum Press, New York 1977. 20 S. R. Cohen, R.M. Herndon and G.M. McKhann New Engl J. Med 295, MSS (1976). 21 S.R. Cohen and H.S. Gutstein. Science 199. 301 (1978) 22 J.H. Carson, E. Barbarese, P.E. Braun and T.A. McPherson Proc. nat. Acad. Sa. USA 75. 1976 (1978). EfTccl of (he polychlorinated biphenyl preparation, Aroclor 1242, on the quantity of neurosecretory material in the medulla tcrminalis X-organ of the Tiddler crab, Ucapugiiator1 R. Nagabhushanam, S.W. Fingerman and M. Fingerman2 Department of 'Zoology, Marathwada University, Aurangabad (India) and Department of Biology, Tulane University, Sew Orleans (Louisiana 70118, USA), 20 October 1978 Summary. Exposure of the fiddler crab, Uca pugitaior. to the PCB preparation, Aroclor 1242, produces an increase in the quantity of neurosecretory material in the medulla terminalis X-organ. This Aroclor apparently inhibits release, but noi synthesis, of one or more neurohormones. Polychlorinated biphenyls (PCBs) arc extremely persistent, globally distributed pollutants3. Many animals, including the fiddler crab, Uca pugiiator, the species used in this investigation, have been found to accumulate PCBs in their tissues^ Exposure of this crab to the PCB preparation, Arocloi 1242, results in decreased dispersion of the pigment in its mclanophores3. Those crahs exposed to Aroclor 1242 had up to 4 times more melanin-dispersing hormone (MI3H), a ncurohormone, in their eyestalks than did con trol crahs. The PCB preparation appeared to inhibit MDH release but not its synthesis. In the evesialk of the fiddler crab, MDH is released from (he sinus glands. These glands are neurohcmal organs. Most, if not all, of the neurosecre tory axons that enter a sinus gland originate in the medulla terminalis X-organ of each eyestalk. In a recent study of the eyestalk of the crayfish, Orconectes virilis, the investigators could find no evidence that neurosecretory axons came from any other area than the medulla terminalis X-organ6. The object of this investigation was to determine whether cytological evidence of an effect of Aroclor 1242 on the neuroendocrine system of the fiddler crab could be ob tained. Materials and methods. Malice female specimens of Uca pugiiator. having a carapace width of 1.5-1.6 cm, from the area of Panacea, Florida, were used. At noon, crabs were selected from the stock supply and placed in white enam eled pans (18 cm diameter) containing artificial sea waicr (Instant Ocean, Aquarium Systems) . '.one, and placed under a constant illumination of 2100 lux at 24 "C. 24 h later those crabs whose mclanophores were at HogbcnSlome stage 3 were selected for further use1. According to the Hogben-Slome scheme stage 3 represents an interme diate degree of pigment dispersion with stage I represent ing maximal concern ration of the pigment and stage 5 maximal dispersion. The selected CTabs were then divided into 2 groups and placed into white enameled pans which contained either 8 ppm Aroclor 1242 (Monsanto Lot Num ber G26cK) in a solution of 0.1% acetone in artificial sea water or only 0.1% acetone in artificial sea water. The Aroclor had first been dissolved in acetone which explains the presence of acetone in both the experimental and control containers. The volume of liquid in each pan was 400 ml. The 2 groups of crabs were again exposed to the constant illumination of 2100 lux at 24 *C for 24 h after which their melanophore stages were again determined and their eyestalks were removed. The internal tissues of both eyestalks from 5 experimental and 5 control crabs wrre then dissected out, fixed in Bouin's solution, embedded in paraffin, cut into longitudinal serial sections 8 pm thick. and stained with Gomori's chrome-alum hematoxylin and 7 DSW 031762 STLCOPCB4015724 Neurosecretory activity in the medulla (erminalis X-organ PC'B-trealcd Crab number 1 2 3 4 5 Staining index 2 3 2 3 3 Control 1 2 3 4 5 Average 2.6* 1 1 2 2 I "Significantly greater than control (pr0 05) Average 1.4 phloxin*. The secretory activity of the neurosecretory cell bodies in the medulla Icmiinaiis X-organ of the sectioned eycsiulks was then evaluated by using the following index rumbers to stage the cells: 0, neurosecretory granules absent; 1, very few granules; 2, intermediate between ! and 3; 3, a large number of granules. This system is essentially that of Mutsumoto, but he numbered his stages 0, I, 3, and 5". A cell whose cytoplasm is crowded with neurosecretory granules presumably contains more neurohormone than does a cell with cw or no granules. Statistical evaluation of the dulu was performed using the Student's t-lest. Remits and discussion. When the eyestalks were removed, the mean melanophore stage of the crabs that had been in the acetone-sea water for 24 b was 3.4 whereas that of the crabs in the PCB preparation was 1.7. This difference (3.4 versus 1.7) and the decrease from the initial melanophore stage (1.7 versus 3.0) were not only statistically significant (p< 0.01 for both) but were also consistent with the pre vious observation that Aroclor 1242 prevents the pigment in the melanophoivs from remaining as dispersed as in con trol crabs'. The slightly increased level of melanin disper sion, up fror-* the original 3.0 to 3.4, in the control crabs was presumably due in large measure to the continuous expo sure to the bright illumination (2100 lux) in contrast to the 422 lux the cr.'bs had been exposed to in the stock tank prior to the Sturt of the experiment. Bright illumination induces melanin dispersion in the fiddler crab10 Examination of the eyestalk sections revealed that the quantity of neurosecretory material in the neurosecretory cell bodies in the medulla terminalis X-organs of the crabs exposed to the PCB preparation was significantly greater than in the control crabs (table). This observation is consis tent with the previously obtained data which showed that eyestalks of crabs exposed to Aroclor 1242 contained more MDH than did eyestalks of control crabs3. Ol cou- se, all of the neurosecretory granules stained were not MDH-containing alone. The eyestalk secretes several different neuro hormone:.". Additional experiments are being perlormed to determine what eyestalk neurohormoncs in addition to MDH are also affected by PCBs. 1 This investigation was supported by grant PCM75-03029 A0I from the National Science Foundation. 2 Reprint requests should be addressed to M F 3 R.W. Risebrough, P. Rieche, D.P. Pcakall, S.G. Herman and M.N. Kirven, Nature 220. 1098 (1968). 4 D.R. Nimmo, P.D. Wilson, R.R. Blackman and A.J. Wilson. Jr, Nature 231. 50 (1971). 5 S.W. Fingcrman and M. Fingerinan, Mar. Biol. 50. 37 (1978). 6 R.D. Andrew, I. Orchard and A.S. M. Saleuddin, Cell Tiss. Res. 190, 235(1978). 7 L. Hogben and D. Slome, Proc. r. Soc. Lond. 10SB. 10 (1931) 8 G. Gomori, Am. J. Path. 57. 395 (1941). 9 K. Matsumoto, Gen. comp. Endocr. 2, 4 (1962). 10 F.A. Brown, Jr, and M.I. Sandcen, Physiol. Zool. 21, 361 (1948). 11 L.H. KJeinholz, Am. Zool. 16, 151 (1976). DSW 031763 Glomerular filtration rate and kidney Wood flow in alloxan and streptozotocin diabetic rats J. M. Foy and A. K.M. Salih School ofStudies in Pharmacology, University of Bradford, Bradford West, Yorkshire BD71 DP (England). 3 November i 978 Summary. C 'omcrular f!tration rate (GFR), cardiac output, regional blood flow and kidney weight were measured in alloxan anti streptozotocin diabetic rats at different times after the administration of diabetogen. A high GFR was found together with increased kidney weight and reduced blood flow. The role of diabetic nephropathy as a cause of death in late diabetes mellitus underlines the importance of studying changes in renal structure and function early in the disease. A measurable thickening of the basement membrane and mesangial region has been clearly shown in recent studies using the electron microscope. It takes place long before the advent of any clinvat evidence of nephropathy1"3. It is thought that this thickening is the forerunner of more advanced disease which leads to renal failure. Recent clinical studies arc agreed in showing an increase in the glomerular filtration rate (GFR) in early diabetes4 7. This elevation of GFR is accompanied by normal or slightly increased renal plasma flow (RPF) in some reports3-1' and reduced RPF in others4. The exact mechanism behind this high GFR is not known. It has been variously suggested that it might be related to an increase in RPF, a decrease in RPF and hence a higher filtration pressure or to an increase in the permeability of the glomeruli. Increased kidney size was also reported to be behind this abnormality,v. All the previously mentioned studies were carried out on human beings where ethical considerations limit the nature of the investigations capable of being executed In particular, simultaneous estimation of cardiac output and renal blood flow, while extremely difficult in humans, is quite feasible in experimental animals, using the labelled microsphere technique previously described 10 Previous work on experimental diabetes has been mainly directed to the toxic effects of the diabetogenic agents on the kidney itself. Alloxan and streptozotocin were both reported to cause renal lesions" 14. However, these lesions were also shown to be due to the diabcMic condition or to STLCOPCB4015725