The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated
The present study examines the effect of concanavalin A (Con A) on the blood insulin and glucose levels of rats. Male and female rats treated with Con A (62.5-500 µg/kg) for three days showed a dose- and time-dependent hyperinsulinemia that lasted more than 48 h. Male rats were more sensitive to Con...
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| Format: | Article |
| Language: | English |
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Associação Brasileira de Divulgação Científica
1998-05-01
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| Series: | Brazilian Journal of Medical and Biological Research |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000500015 |
| _version_ | 1818559165874831360 |
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| author | J. Francisco-DoPrado J.E. Zambelli M.H. Melo-Lima G. Ribeiro-DaSilva |
| author_facet | J. Francisco-DoPrado J.E. Zambelli M.H. Melo-Lima G. Ribeiro-DaSilva |
| author_sort | J. Francisco-DoPrado |
| collection | DOAJ |
| description | The present study examines the effect of concanavalin A (Con A) on the blood insulin and glucose levels of rats. Male and female rats treated with Con A (62.5-500 µg/kg) for three days showed a dose- and time-dependent hyperinsulinemia that lasted more than 48 h. Male rats were more sensitive to Con A. Thus, 6 h after treatment with Con A the circulating insulin levels in male rats had increased by 85% (control: 10.2 ± 0.9 mU/l and Con A-treated: 18.8 ± 1 mU/l) compared to only 38% (control: 7.5 ± 0.2 mU/l; Con A-treated: 10.3 ± 0.9 mU/l) in females. An identical response was seen after 12 h. Con A (250 µg/kg) produced time-dependent hypoglycemia in both sexes but more pronounced in males. There was no correlation between the hypoglycemia and hyperinsulinemia described above. The Con A-induced hyperinsulinemia in rats of both sexes was abolished in gonadectomized animals (intact males: +101 ± 17% vs orchiectomized males: -5 ± 3%; intact females: +86 ± 23% vs ovariectomized females: -18 ± 7.2%). Pretreating intact male and female rats with human chorionic gonadotropin also significantly inhibited the Con A-induced hyperinsulinemia. Estradiol (10 µg/kg, im) significantly blocked the Con A-induced increase in circulating insulin in male rats (101 ± 17% for controls vs 32 ± 5.3% for estradiol-treated animals, P<0.05) while testosterone (10 mg/kg, im) had no similar effect on intact female rats. Pretreating Con A-injected rats with opioid antagonists such as naloxone (1 mg/kg, sc) and naltrexone (5 mg/kg, sc) blocked the hyperinsulinemia produced by the lectin in males (control: +101 ± 17% vs naloxone-treated: +5 ± 14%, or naltrexone-treated: -23 ± 4.5%) and females (control: +86 ± 23% vs naloxone-treated: +21 ± 20%, or naltrexone-treated: -18 ± 11%). These results demonstrate that Con A increases the levels of circulating insulin in rats and that this response is opioid-dependent and hormonally regulated. |
| first_indexed | 2024-12-14T00:21:50Z |
| format | Article |
| id | doaj.art-28e5bb58ba88442185b2889021d51f09 |
| institution | Directory Open Access Journal |
| issn | 0100-879X 1414-431X |
| language | English |
| last_indexed | 2024-12-14T00:21:50Z |
| publishDate | 1998-05-01 |
| publisher | Associação Brasileira de Divulgação Científica |
| record_format | Article |
| series | Brazilian Journal of Medical and Biological Research |
| spelling | doaj.art-28e5bb58ba88442185b2889021d51f092022-12-21T23:25:11ZengAssociação Brasileira de Divulgação CientíficaBrazilian Journal of Medical and Biological Research0100-879X1414-431X1998-05-0131569710.1590/S0100-879X1998000500015The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulatedJ. Francisco-DoPradoJ.E. ZambelliM.H. Melo-LimaG. Ribeiro-DaSilvaThe present study examines the effect of concanavalin A (Con A) on the blood insulin and glucose levels of rats. Male and female rats treated with Con A (62.5-500 µg/kg) for three days showed a dose- and time-dependent hyperinsulinemia that lasted more than 48 h. Male rats were more sensitive to Con A. Thus, 6 h after treatment with Con A the circulating insulin levels in male rats had increased by 85% (control: 10.2 ± 0.9 mU/l and Con A-treated: 18.8 ± 1 mU/l) compared to only 38% (control: 7.5 ± 0.2 mU/l; Con A-treated: 10.3 ± 0.9 mU/l) in females. An identical response was seen after 12 h. Con A (250 µg/kg) produced time-dependent hypoglycemia in both sexes but more pronounced in males. There was no correlation between the hypoglycemia and hyperinsulinemia described above. The Con A-induced hyperinsulinemia in rats of both sexes was abolished in gonadectomized animals (intact males: +101 ± 17% vs orchiectomized males: -5 ± 3%; intact females: +86 ± 23% vs ovariectomized females: -18 ± 7.2%). Pretreating intact male and female rats with human chorionic gonadotropin also significantly inhibited the Con A-induced hyperinsulinemia. Estradiol (10 µg/kg, im) significantly blocked the Con A-induced increase in circulating insulin in male rats (101 ± 17% for controls vs 32 ± 5.3% for estradiol-treated animals, P<0.05) while testosterone (10 mg/kg, im) had no similar effect on intact female rats. Pretreating Con A-injected rats with opioid antagonists such as naloxone (1 mg/kg, sc) and naltrexone (5 mg/kg, sc) blocked the hyperinsulinemia produced by the lectin in males (control: +101 ± 17% vs naloxone-treated: +5 ± 14%, or naltrexone-treated: -23 ± 4.5%) and females (control: +86 ± 23% vs naloxone-treated: +21 ± 20%, or naltrexone-treated: -18 ± 11%). These results demonstrate that Con A increases the levels of circulating insulin in rats and that this response is opioid-dependent and hormonally regulated.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000500015concanavalin Ahyperinsulinemiablood glucose alterationssex hormonesendogenous opioidscanatoxin |
| spellingShingle | J. Francisco-DoPrado J.E. Zambelli M.H. Melo-Lima G. Ribeiro-DaSilva The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated Brazilian Journal of Medical and Biological Research concanavalin A hyperinsulinemia blood glucose alterations sex hormones endogenous opioids canatoxin |
| title | The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated |
| title_full | The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated |
| title_fullStr | The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated |
| title_full_unstemmed | The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated |
| title_short | The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated |
| title_sort | hyperinsulinemia produced by concanavalin a in rats is opioid dependent and hormonally regulated |
| topic | concanavalin A hyperinsulinemia blood glucose alterations sex hormones endogenous opioids canatoxin |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000500015 |
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