Long term effects of morphine on mesangial cell proliferation and matrix synthesis

P. C. Singhal, N. Gibbons, M. Abramovici

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48 Scopus citations

Abstract

Since focal glomerulosclerosis is the predominant glomerular lesion in heroin nephropathy and since mesangial expansion is considered to be a precursor of glomerulosclerosis, we have evaluated the effect of opiates on mesangial cell (MC) proliferation and matrix synthesis. We showed, using a fluorometric assay, that MC are not capable of metabolizing heroin to its active metabolite morphine. Cells exposed to morphine (10-5 M or 10-4 M) in prolonged cultures either continuously (Group A) or intermittently (Group B) showed enhanced incorporation of [3H]thymidine when compared to control cells (control, 88600 ± 26303 cpm/well vs. morphine 10-4 M - Group A, 321203 ± 52867, P < 0.001; control vs. morphine 10-4 M - Group B, 223126 ± 46866 cpm/well, P < 0.01; control, 107593 ± 42284 cpm/well vs. morphine 10-5 M - Group A, 267108 ± 41866 cpm/well, P < 0.001; control vs. morphine 10-5 M - Group B, 202317 ± 24325 cpm/well, P < 0.05). However, MC incubated with a lower concentration of morphine (10-6 M) enhanced DNA synthesis when exposed intermittently only (control, 107593 ± 42284 cpm/well vs. Group B, 219164 ± 15552 cpm/well, P < 0.05). This growth stimulating effect of morphine (10-6 M and 10-5 M) was also observed at earlier time points, that is, one- and one-and-a-half-week old cultures. However, in one-week-old cultures, morphine in a higher concentration (10-4 M) showed a suppressive effect (P < 0.05) on MC proliferation (morphine, 3620 ± 220 cpm/well vs. control, 4668 ± 410 cpm/well). This effect not only subsided by one and a half weeks but morphine (10-4 M) treated cells enhanced MC proliferation. An opioid antagonist, naloxone attenuated the effect of morphine in one and half week old cultures. Morphine at 10-6 M to 10-4 M concentrations enhanced incorporation of [3H]proline in the extracellular proline pool (a component of mesangial matrix) when compared to control (control, 309661 ± 3992 vs. morphine 10-4 M, 363104 ± 10539 cpm/well, P < 0.05 or morphine 10-5 M, 397954 ± 31008 cpm/well, P < 0.001 or morphine 10-6 M, 384630 ± 26369 cpm/well, P < 0.01). In addition, MC incubated with morphine (10-6 M and 10-4 M) also enhanced (P < 0.001) synthesis of laminin. MC incubated with morphine (10-5 M or 10-4, 12 weeks) had a greater number of hillocks (foci of cell proliferation and aggregated matrix) when compared with untreated cells. Morphine treated MC synthesized a decreased amount of PGE2 (129 ± 48 pg/mg protein, P < 0.02) when compared to PGE2 production by untreated cells (493 ± 123 pg/mg protein). Morphine pretreated MC when stimulated with arginine vasopressin (AVP, 10-6 M) also produced a lesser amount of PGE2 (214 ± 51 pg/mg protein, P < 0.05) when compared to PGE2 production by control cells under stimulation with AVP (1393 ± 451 pg/mg protein). Our results suggest that morphine may be playing a direct role in mesangial expansion in opiate addicts.

Original languageEnglish
Pages (from-to)1560-1570
Number of pages11
JournalKidney International
Volume41
Issue number6
DOIs
StatePublished - 1992
Externally publishedYes

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