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The cocaine-induced elevation of plasma corticosterone is mediated by endogenous corticotropin-releasing factor (CRF) in rats
Brain Research, 589 (1992) 154-156 © 1992 Elsevier Science Publishers B.V. All rights reserved 0006-8993/92/$05.00
154
BRES 25328
The cocaine-induced elevation of plasma corticosterone is mediated by endogenous corticotropin-releasing factor (CRF) in rats Zoltfin Sarnyai a, l~va Bir6 a, B o t o n d P e n k e b a n d G y u l a T e l e g d y
a
u Institute of Pathophysiology and h h~stitute of Medical Chemistry, Albert Szent-Gyiirgyi Medical Unil'ersity, Szeged (Hungary) (Accepted 2 June 1992)
Key words: Cocaine; Corticosterone; Corticotropin-releasing factor
The role of endogenous corticotropin-releasing factor (CRF) in the cocaine-induced corticosterone response was investigated by using the immunoncutralization and receptor blockade of endogenous CRF. Pretreatment with different dilutions (1:5, 1:10 and 1:20, i.c.v.) of CRF antibody and different doses of an antagonist for CRF receptors, o~-helicalCRFg_4t (oeh-CRF, 0.001-1.0 p.g, i.c,v.), dose-dependently prevented the cocaine-induced increase in corticosterone level. These results support the hypothesis that the activation of the hypothalamo-pituitary-adrenal (HPA) axis by cocaine is mediated through the release of endogenous CRF.
Recent evidence suggests that cocaine alters neuroendocrine functions. Cocaine has been demonstrated to stimulate the secretion of ACTH ts'~, corticosterone TM (CORT) and /3-endorphin II in rats. Although the site of action of cocaine on the HPA axis is currently unknown, it does not appear to act directly on the pituitary, as cocaine did not stimulate ACTH release from cultured pituitary cells ~'~.In addition, CRF immunoncutralization studies suggest that this effect of cocaine is dependent on endogenous CRF ~5. Cocaine has also been reported to stimulate the release of CRF from a rat hypothalamic organic culture system in vitro 2. The following experiments were therefore designed to investigate the role of endogenous CRF in the activation of the HPA axis by cocaine, with the inl'dbition of endogenous CRF by the immunoneutralization and receptor blockade of CRF in rats. Male rats of the Wistar strain (LATI, G/~d/Sll6, Hungary) weighing 180-200 g were used. Five animals were housed per cage and kept at room temperature under a constant light-dark cycle (lights on between 06.00 and 18.00 h). Five days prior to the experimental session, the animals were subjected to the surgical
procedure. For the i.c.v, injection, animals were operated on under sodium pentobarbital (Nembutal, CEVA, Paris, France, 40 mg/kg, i.p.) anesthesia using a stereotaxic apparatus. A 23-gauge steel guide cannula was inserted unilaterally into the right lateral cerebral ventricle according to the coordinates of Pellegrino et al. ~2 Thus, the tip of the cannula rested 1 mm above the intended site of injection, Cannula placement was verified by visual inspection following injection of blue dye through the cannula after the experiment. Only data from animals with accurate placement were considered for further investigations. Different dilutions of CRF antibody (CRF-Ab) (kindly donated by Paul Vecsei, Department of Pharmacology, University of Heidelberg, Germany) and normal rabbit serum were injected i.c.v. 24 h prior to cocaine (cocaine hydrochloride, E. Merck, Darmstadt, FRG). ah-CRF (synthetized and kindly donated by J. Riv[er, La Jolla, CA, USA) was administered 30 min before the cocaine treatment. The i.c.v, treatments were performed by Hamilton microsyringe in a volume of 2 pl/animai with a 2 min/injection velocity. 30 rain after the cocaine or vehicle treatment, animals were decapitated, and the trunk blood was col-
Correspondence: Z. Sarnyai, Alcohol and Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA, USA.
155 lected in a heparinized glass tube and the plasma CORT level was measured by fluorimetry as described earlier 6J6. Statistical analysis of the data was performed by one-way ANOVA, followed by Tukey's tests for multiple comparison. A probability level of 0.05 was accepted as indicating a significant difference. Pretreatment with different dilutions of CRF antiserum (1"5, 1" 10 and 1:20, but not 1" 100) totally blocked the CORT level elevation induced by cocaine (dilution 1" 5 F3,42 - 214.78, P < 0.0001, P < 0.05 NRS + COC vs. CRF-Ab + COC; dilution 1" 10 F3,40 = 110.94, P < 0.0001, P < 0.05 NRS + COC vs. CRF-Ab + COC; dilution 1" 20 F3.4= - 101.76, P < 0.0001, P < 0.05 NRS + COC vs. CRF-Ab + COC, dilution 1" 100 F3,34 = 155.62, P < 0.0001, P > 0.05 NRS + COC vs. CRF-Ab + COCk as depicted in Fig. 1. None of the dilutions of CRF-Ab produced any alterations in the CORT level in saline-treated control rats. Fig. 2 demonstrates the effect of a h-CRF on the cocaine-induced elevation of the plasma CORT level. a h-CRF itself did not modifythe CORT levels of the saline treated controls. The CORT response was inhibited dose-dependently (FtM2 s = 102.84; P < 0.0001, P < 0.05) by pretreatment with the CRF-receptor antagonist. Our results clearly show that the action of cocaine on the HPA axis depends on the presence of endogenous CRF. This observation is consistent to the result
I
1:5
I
20
1:10
20
I u 2o ,~
NRS CRF-Ab Sol Coc Sol Coc
NRS CRF-Ab Sal Coc Sal Coc .1,20 •
NRS CRF-Ab Sol Coc Sol Coc
I
.1:100
20
NRS CRF-Ab Sol Coc Sol Coc
Fig. 1. Effects of different dilutions of C R F antiserum on cocaine-induced elevation of plasma corticosterone. Corticosterone values are expressed in /~g/100 ml plasma (mean+S.E.M.). Numbers in bars are the numbers of animals per group. NRS, normal rabbit serum; CFR-Ab, corticotropin-releasing factor antibody; Sal, 0.9% NaCI; Coc, cocaine (7.5 m g / k g , s.c.). * P <0.05 vs. NRS+Sal-treated control; • P < 0.05 vs. NRS + Coc-treated animals.
O
E
ol O CL
Coc ~-
(16)
E O O
E
ok..
Sol
:16)
ul O
"-g.,.-,
0.001
0.01
0.1
1.0 .ug ,/,h-CRF
0 u Fig. 2. Effects of different doses of CRF receptor antagonist (ahCRF) on cocaine-induced plasma corticosterone response. Abbreviations: Sal, 0.9%NaCI; Coc, cocaine (7.5 m g / k g , s.c.); open bars represent animals treated with different doses of a h - C R F plus saline; shaded bars represent animals treated with a h - C R F plus cocaine; numbers in bars and in brackets indicate the numbers of animals per group; * P < 0.05 vs. saline-treated c o n t r o l ; ° p < 0.05 vs. cocaine-treated animals.
of Rivier and Vale =5 who demonstrated the inhibitory effect of intravenously (i.v.) administered CRF antiserum on the ACTH response to cocaine. In that experiment, the i.v. route of administration of CRF antiserum allowed neutralization of the endogenous CRF in the hypophyseal portal blood. The i.c.v, injection of CRF antiserum 24 h before cocaine treatment may neutralize the CRF locally in the hypothalamus. The dose-dependent inhibitory effect of ah-CRF, as an antagonist for CRF receptors, on the elevation of plasma CORT by cocaine could be explained in that t~h-CRF might reach the CRF receptors on the anterior pituitary through the median eminence and the portal circulation. The activation of the HPA axis is the most important mediator of the neuroendocrine response to stress =4. There is certain evidence of possible connections between stress and psychostimulant addiction. Cole and co-workers 4 demonstrated that the intact HPA axis may be essential for the development of amphetamine sensitization in rats. The behavioral sensitization to repeated stress may also be mediated by the activation of endogenous CRF a. The close relations between the individual reactivity to novelty, which predicts the probability of psychostimulant self-administration, the CORT level and the hippocampal CORT receptor affinity have also been demonstrated ~3. The cocaine-CRF interaction seems to be important not only in the etiology of psychostimulant addiction, but also in the consequence of the chronic use of cocaine. Cocaine produces behavioral anxiety in rats 7'9 and the
156
anxiogenic property of CRF has also been demonstrated in rats s and in primates ~°. Chronic cocaine treatment resulted in a significant decrease in CRF receptor labeling primarily in brain areas associated with the mesolimbic/mesocorticai dopaminergic systems 8, which suggests an increased level of endogenous CRF as an initiator for cocaine-induced anxiety. These data raise the possibility of the putative role of endogenous CRF in the mediation of neurobiologicai consequences of cocaine addiction. Our present ~csult provides further strong evidence of the role of endogenous CRF released from the hypothalamus and the CRF receptors in the mediation of the cocaine-induced activation of the HPA axis, and suggests the possible use of the modulation of CRF and/or glucocorticoid receptors in the treatment of neuroendocrine and behavioral consequences of cocaine abuse. ! Borowsky, B. and Kuhn, C.M., Monoamine mediation of cocaine-induced hypothalamopituitary-adrenal activation, J. Pharmacol. Exp. Ther., 256 (19ql) 204-210. 2 Calogero, A.E., Gallucci, W.T., Kling, M.A., Chrousos, G.P. and Gold, P.W., Cocaine stimulates rat hypothalamic corticotropin-releasing hormone secretion in vitro, Brain Res., 505 (1989) 7-11. 3 Cole. BJ., Cador, M., Stinus, L., Rivier, C., Rivier, J., Vale, W., Koob, G.F. and LeMoal, M., Central administration of a CRF antagonist blocks the development of stress-induced behavioral sensitization, Braht R~:s'.,512 (1990) 343-346. 4 Cole, BJ., Cador, M., Stinus, L., Rivier, C., Rivier, J., Vale, W., LcMoal, M. and Koob, G.F., Critical role of hypothalamic pitu-
5
6
7 8 9 10
11 12 13
14 15 16
itary adrenal axis in amphetamine-induced sensitization of behavior, Life ScL, 47 (19~) 1715-1720. Dunn, AJ. and Berridge, C.W., Physiological and behavioral response to corticotropin-releasing factor administration: is CRF a mediator of anxiety or stress responses?, Brain Res. Ret'., 15 (1990) 71-100. Fekete, M., Bokor, M., Penke, B., Kovfics, K. and Telegdy, G., Effects of cholecystokinin octapeptide and its fragments on brain monoamines and plasma corticosterone, Neurochem. Int., 3 (1981) 165-169. Fontana, D.J. and Commissaris, R.L., Effects of cocaine on conflict behavior in rat, Life Sci., 45 (1989) 819-827. Goeders, N.E., Bienvenu, O.J. and De Souza, E.B., Chronic cocaine administration alters corticotropin-releasing factor receptors in the rat brain, Brain Res., 531 (1990) 322-328. Gorman, A.L., Yang, X.M., Dunn, A.J. and Goeders, N.E., Anxiogenic effects of cocaine, Soc. Neurosci. Abstr., in press. Kalin, N.H., Shelton, S.E., Kraemer, G.W. and McKinney, W.T., Associated endocrine, physiological and behavioral changes in rhesus-monkeys after intravenous corticotropin-releasing factor administration, Peptides, 4 (1983) 211-215. Moldow, R.L. and Fischman, A.J., Cocaine induced secretion of ACTH, /3-endorphin, and corticosterone, Peptides, 456 (1987) 819-822. Pellegrino, UJ., Pellegrino, A.S. and Cushman A.J., A Stereotactk" Atlas of the Rat Brain, Plenum, New York, 1979. Piazza, P.V., Maccari, S., Deminiere, J.-M., LeMoal, M., Mormede, M. and Simon, H., Corticosterone levels determine individual vulnerability to amphetamine self-administration, Proc. Natl. Acad. Sci. USA, 88 (1991) 2088-2092. Rivier, C.L. and PIotsky, P.M., Mediation by corticotropin-releasing factor (CRF) of adenohypophyseal hormone secretion, Annu. Rel'. Physiol., 48 (I 986) 475-494. Rivier, C. and Vale, W., Cocaine stimulates adrenocorticotropin (ACTH) secretion through a corticotropin-releasing factor (CRF)-mediated mechanism, Brain Res., 422 (1987) 403-406. Zenker, N. and Bernstein, D.E., The estimation of small amounts of corticosterone in rat plasma, J. Biol, Chem., 231 (I 958) 695-701.
154
BRES 25328
The cocaine-induced elevation of plasma corticosterone is mediated by endogenous corticotropin-releasing factor (CRF) in rats Zoltfin Sarnyai a, l~va Bir6 a, B o t o n d P e n k e b a n d G y u l a T e l e g d y
a
u Institute of Pathophysiology and h h~stitute of Medical Chemistry, Albert Szent-Gyiirgyi Medical Unil'ersity, Szeged (Hungary) (Accepted 2 June 1992)
Key words: Cocaine; Corticosterone; Corticotropin-releasing factor
The role of endogenous corticotropin-releasing factor (CRF) in the cocaine-induced corticosterone response was investigated by using the immunoncutralization and receptor blockade of endogenous CRF. Pretreatment with different dilutions (1:5, 1:10 and 1:20, i.c.v.) of CRF antibody and different doses of an antagonist for CRF receptors, o~-helicalCRFg_4t (oeh-CRF, 0.001-1.0 p.g, i.c,v.), dose-dependently prevented the cocaine-induced increase in corticosterone level. These results support the hypothesis that the activation of the hypothalamo-pituitary-adrenal (HPA) axis by cocaine is mediated through the release of endogenous CRF.
Recent evidence suggests that cocaine alters neuroendocrine functions. Cocaine has been demonstrated to stimulate the secretion of ACTH ts'~, corticosterone TM (CORT) and /3-endorphin II in rats. Although the site of action of cocaine on the HPA axis is currently unknown, it does not appear to act directly on the pituitary, as cocaine did not stimulate ACTH release from cultured pituitary cells ~'~.In addition, CRF immunoncutralization studies suggest that this effect of cocaine is dependent on endogenous CRF ~5. Cocaine has also been reported to stimulate the release of CRF from a rat hypothalamic organic culture system in vitro 2. The following experiments were therefore designed to investigate the role of endogenous CRF in the activation of the HPA axis by cocaine, with the inl'dbition of endogenous CRF by the immunoneutralization and receptor blockade of CRF in rats. Male rats of the Wistar strain (LATI, G/~d/Sll6, Hungary) weighing 180-200 g were used. Five animals were housed per cage and kept at room temperature under a constant light-dark cycle (lights on between 06.00 and 18.00 h). Five days prior to the experimental session, the animals were subjected to the surgical
procedure. For the i.c.v, injection, animals were operated on under sodium pentobarbital (Nembutal, CEVA, Paris, France, 40 mg/kg, i.p.) anesthesia using a stereotaxic apparatus. A 23-gauge steel guide cannula was inserted unilaterally into the right lateral cerebral ventricle according to the coordinates of Pellegrino et al. ~2 Thus, the tip of the cannula rested 1 mm above the intended site of injection, Cannula placement was verified by visual inspection following injection of blue dye through the cannula after the experiment. Only data from animals with accurate placement were considered for further investigations. Different dilutions of CRF antibody (CRF-Ab) (kindly donated by Paul Vecsei, Department of Pharmacology, University of Heidelberg, Germany) and normal rabbit serum were injected i.c.v. 24 h prior to cocaine (cocaine hydrochloride, E. Merck, Darmstadt, FRG). ah-CRF (synthetized and kindly donated by J. Riv[er, La Jolla, CA, USA) was administered 30 min before the cocaine treatment. The i.c.v, treatments were performed by Hamilton microsyringe in a volume of 2 pl/animai with a 2 min/injection velocity. 30 rain after the cocaine or vehicle treatment, animals were decapitated, and the trunk blood was col-
Correspondence: Z. Sarnyai, Alcohol and Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA, USA.
155 lected in a heparinized glass tube and the plasma CORT level was measured by fluorimetry as described earlier 6J6. Statistical analysis of the data was performed by one-way ANOVA, followed by Tukey's tests for multiple comparison. A probability level of 0.05 was accepted as indicating a significant difference. Pretreatment with different dilutions of CRF antiserum (1"5, 1" 10 and 1:20, but not 1" 100) totally blocked the CORT level elevation induced by cocaine (dilution 1" 5 F3,42 - 214.78, P < 0.0001, P < 0.05 NRS + COC vs. CRF-Ab + COC; dilution 1" 10 F3,40 = 110.94, P < 0.0001, P < 0.05 NRS + COC vs. CRF-Ab + COC; dilution 1" 20 F3.4= - 101.76, P < 0.0001, P < 0.05 NRS + COC vs. CRF-Ab + COC, dilution 1" 100 F3,34 = 155.62, P < 0.0001, P > 0.05 NRS + COC vs. CRF-Ab + COCk as depicted in Fig. 1. None of the dilutions of CRF-Ab produced any alterations in the CORT level in saline-treated control rats. Fig. 2 demonstrates the effect of a h-CRF on the cocaine-induced elevation of the plasma CORT level. a h-CRF itself did not modifythe CORT levels of the saline treated controls. The CORT response was inhibited dose-dependently (FtM2 s = 102.84; P < 0.0001, P < 0.05) by pretreatment with the CRF-receptor antagonist. Our results clearly show that the action of cocaine on the HPA axis depends on the presence of endogenous CRF. This observation is consistent to the result
I
1:5
I
20
1:10
20
I u 2o ,~
NRS CRF-Ab Sol Coc Sol Coc
NRS CRF-Ab Sal Coc Sal Coc .1,20 •
NRS CRF-Ab Sol Coc Sol Coc
I
.1:100
20
NRS CRF-Ab Sol Coc Sol Coc
Fig. 1. Effects of different dilutions of C R F antiserum on cocaine-induced elevation of plasma corticosterone. Corticosterone values are expressed in /~g/100 ml plasma (mean+S.E.M.). Numbers in bars are the numbers of animals per group. NRS, normal rabbit serum; CFR-Ab, corticotropin-releasing factor antibody; Sal, 0.9% NaCI; Coc, cocaine (7.5 m g / k g , s.c.). * P <0.05 vs. NRS+Sal-treated control; • P < 0.05 vs. NRS + Coc-treated animals.
O
E
ol O CL
Coc ~-
(16)
E O O
E
ok..
Sol
:16)
ul O
"-g.,.-,
0.001
0.01
0.1
1.0 .ug ,/,h-CRF
0 u Fig. 2. Effects of different doses of CRF receptor antagonist (ahCRF) on cocaine-induced plasma corticosterone response. Abbreviations: Sal, 0.9%NaCI; Coc, cocaine (7.5 m g / k g , s.c.); open bars represent animals treated with different doses of a h - C R F plus saline; shaded bars represent animals treated with a h - C R F plus cocaine; numbers in bars and in brackets indicate the numbers of animals per group; * P < 0.05 vs. saline-treated c o n t r o l ; ° p < 0.05 vs. cocaine-treated animals.
of Rivier and Vale =5 who demonstrated the inhibitory effect of intravenously (i.v.) administered CRF antiserum on the ACTH response to cocaine. In that experiment, the i.v. route of administration of CRF antiserum allowed neutralization of the endogenous CRF in the hypophyseal portal blood. The i.c.v, injection of CRF antiserum 24 h before cocaine treatment may neutralize the CRF locally in the hypothalamus. The dose-dependent inhibitory effect of ah-CRF, as an antagonist for CRF receptors, on the elevation of plasma CORT by cocaine could be explained in that t~h-CRF might reach the CRF receptors on the anterior pituitary through the median eminence and the portal circulation. The activation of the HPA axis is the most important mediator of the neuroendocrine response to stress =4. There is certain evidence of possible connections between stress and psychostimulant addiction. Cole and co-workers 4 demonstrated that the intact HPA axis may be essential for the development of amphetamine sensitization in rats. The behavioral sensitization to repeated stress may also be mediated by the activation of endogenous CRF a. The close relations between the individual reactivity to novelty, which predicts the probability of psychostimulant self-administration, the CORT level and the hippocampal CORT receptor affinity have also been demonstrated ~3. The cocaine-CRF interaction seems to be important not only in the etiology of psychostimulant addiction, but also in the consequence of the chronic use of cocaine. Cocaine produces behavioral anxiety in rats 7'9 and the
156
anxiogenic property of CRF has also been demonstrated in rats s and in primates ~°. Chronic cocaine treatment resulted in a significant decrease in CRF receptor labeling primarily in brain areas associated with the mesolimbic/mesocorticai dopaminergic systems 8, which suggests an increased level of endogenous CRF as an initiator for cocaine-induced anxiety. These data raise the possibility of the putative role of endogenous CRF in the mediation of neurobiologicai consequences of cocaine addiction. Our present ~csult provides further strong evidence of the role of endogenous CRF released from the hypothalamus and the CRF receptors in the mediation of the cocaine-induced activation of the HPA axis, and suggests the possible use of the modulation of CRF and/or glucocorticoid receptors in the treatment of neuroendocrine and behavioral consequences of cocaine abuse. ! Borowsky, B. and Kuhn, C.M., Monoamine mediation of cocaine-induced hypothalamopituitary-adrenal activation, J. Pharmacol. Exp. Ther., 256 (19ql) 204-210. 2 Calogero, A.E., Gallucci, W.T., Kling, M.A., Chrousos, G.P. and Gold, P.W., Cocaine stimulates rat hypothalamic corticotropin-releasing hormone secretion in vitro, Brain Res., 505 (1989) 7-11. 3 Cole. BJ., Cador, M., Stinus, L., Rivier, C., Rivier, J., Vale, W., Koob, G.F. and LeMoal, M., Central administration of a CRF antagonist blocks the development of stress-induced behavioral sensitization, Braht R~:s'.,512 (1990) 343-346. 4 Cole, BJ., Cador, M., Stinus, L., Rivier, C., Rivier, J., Vale, W., LcMoal, M. and Koob, G.F., Critical role of hypothalamic pitu-
5
6
7 8 9 10
11 12 13
14 15 16
itary adrenal axis in amphetamine-induced sensitization of behavior, Life ScL, 47 (19~) 1715-1720. Dunn, AJ. and Berridge, C.W., Physiological and behavioral response to corticotropin-releasing factor administration: is CRF a mediator of anxiety or stress responses?, Brain Res. Ret'., 15 (1990) 71-100. Fekete, M., Bokor, M., Penke, B., Kovfics, K. and Telegdy, G., Effects of cholecystokinin octapeptide and its fragments on brain monoamines and plasma corticosterone, Neurochem. Int., 3 (1981) 165-169. Fontana, D.J. and Commissaris, R.L., Effects of cocaine on conflict behavior in rat, Life Sci., 45 (1989) 819-827. Goeders, N.E., Bienvenu, O.J. and De Souza, E.B., Chronic cocaine administration alters corticotropin-releasing factor receptors in the rat brain, Brain Res., 531 (1990) 322-328. Gorman, A.L., Yang, X.M., Dunn, A.J. and Goeders, N.E., Anxiogenic effects of cocaine, Soc. Neurosci. Abstr., in press. Kalin, N.H., Shelton, S.E., Kraemer, G.W. and McKinney, W.T., Associated endocrine, physiological and behavioral changes in rhesus-monkeys after intravenous corticotropin-releasing factor administration, Peptides, 4 (1983) 211-215. Moldow, R.L. and Fischman, A.J., Cocaine induced secretion of ACTH, /3-endorphin, and corticosterone, Peptides, 456 (1987) 819-822. Pellegrino, UJ., Pellegrino, A.S. and Cushman A.J., A Stereotactk" Atlas of the Rat Brain, Plenum, New York, 1979. Piazza, P.V., Maccari, S., Deminiere, J.-M., LeMoal, M., Mormede, M. and Simon, H., Corticosterone levels determine individual vulnerability to amphetamine self-administration, Proc. Natl. Acad. Sci. USA, 88 (1991) 2088-2092. Rivier, C.L. and PIotsky, P.M., Mediation by corticotropin-releasing factor (CRF) of adenohypophyseal hormone secretion, Annu. Rel'. Physiol., 48 (I 986) 475-494. Rivier, C. and Vale, W., Cocaine stimulates adrenocorticotropin (ACTH) secretion through a corticotropin-releasing factor (CRF)-mediated mechanism, Brain Res., 422 (1987) 403-406. Zenker, N. and Bernstein, D.E., The estimation of small amounts of corticosterone in rat plasma, J. Biol, Chem., 231 (I 958) 695-701.