Archives of Andrology Journal of Reproductive Systems
ISSN: 0148-5016 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/iaan19
Effect of pimozide on the response of LH-RH in intact adult male rats V. Rettori, S. Goijman & R. Rozados To cite this article: V. Rettori, S. Goijman & R. Rozados (1979) Effect of pimozide on the response of LH-RH in intact adult male rats, Archives of Andrology, 3:2, 135-138, DOI: 10.3109/01485017908985060 To link to this article: http://dx.doi.org/10.3109/01485017908985060
Published online: 09 Jul 2009.
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Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iaan19 Download by: [Australian National University]
Date: 08 June 2016, At: 21:43
Effect of Pimozide on the Response of LH-RH in Intact Adult Male Rats
V. RETTORI,S. GOIJMAN, and R. ROZADOS
Downloaded by [Australian National University] at 21:43 08 June 2016
The effect of Pimozide on serum and pituitary concentration of LH was studied in adult male intact rats. Also the release of LH under stimulation of exogenous LH-RH was measured. The treatment for 5 days with pimozide did not alter the serum LH levels, decreased the release of LH by exogenous LH-RH stimulation, and increased the pituitary LH concentration. These results would indicate that blocking the dopaminergic receptors alters pituitary LH release mechanism. Key Words: Pimozide; Dopamine receptors; Pituitary; Gonadotropins; LH-RH.
INTRODUCTION
Pimozide, a clinically effective neuroleptic drug that specifically blocks dopaminergic receptors [7], increases serum prolactin levels in rats [ 141. This drug is also able to alter serum gonadotropin levels in rats [ 1,141 and humans [ 101, and to inhibit the release of LH by LH-RH but it does not alter the basal release of LH in a culture of dispersed rat anterior pituitary cells [4]. The present investigation was undertaken to study the effect of Pimozide on serum and pituitary LH levels in intact adult male rats, and the release of LH by exogenously administered LH-RH in animals treated with Pimozide. Prolactin levels were also measured. MATERIAL AND METHODS Forty male rats of the Wistar strain (mean weight 250 g) were maintained on a diet of laboratory chow, vegetables, and water ad libidum. The photoperiod was 14 hr light every 24 hr. One group of 20 rats were injected subcutaneously for 5 days with 15 mgl100 g/day of Pimozide dissolved in 0.1 M tartaric acid. Another group of 20 rats was injected with vehicle (0.1 M tartaric acid) also for 5 days. On the 5th day the rats treated with Pimozide or with the control vehicle were injected with LH-RH (dissolved in 0.2 ml acidified saline) I.V. at a dose of 100 mglrat or with 0.2 ml acidified saline alone. Twenty minutes after the injection of LH-RH or acidified saline, the rats were sacrificed by decapitation. Blood was collected from the trunk and the serum was separated by centrifugation and kept frozen until assayed. The pituitary glands were dissected free from the neural lobe, weighed, homogenized in saline and kept frozen. Levels of LH were measured by the double antibody method [ 131. An ovine LH preparation was used for labelling with The first antibody was an antiovine L H serum. NIAMDD-Rat-LH RPl was used as the standard preparation. Received April 1979; revised June 11, 1979. From the Centro de Investigaciones en Reproduccion, Buenos Aires, Argentina. Address reprint requests to: V. Rettori, Centro de Investigaciones en Reproduccion, Facultad de Medicina, Paraguay 2155 piso 10, 1121 Buenos Aires, Argentina.
135 D Elsevier North Holland, Inc.. ARCHIVES OF ANDROLOGY 3, 135-138 (1979)
o14a~o1~~/o6o13~~oo4/5o2.25
136
V. Rettori, S. Goijman, and R. Rozados TABLE 1 The Inhibitory Effect of Pimozide on LH-RH Induced Release of RH as Analyzed by the Factorial Variance Test
fv
d.
OF
between animals pimozide LH-RH interaction pim. LH-RH
9 1
I 1
F
SIGNIF. N.S.
0.95 (7.14) (119.4) 10.5
p p p
< 0.05 Q
0.0001
< 0.01
27
error
Downloaded by [Australian National University] at 21:43 08 June 2016
f.
The prolactin was measured by radioimmunoassay using the NIAMDD rat prolactin RPl. The results were evaluated statistically by means of Student's t Test and Factorial approach to Analysis of Variance [16]. Pimozide (1(-4,4,-bis(p-fluorophenyl)butyl-4-piperidyl)-2-benzimidazolinone) was a gift from Johnson & Johnson Laboratories and LH-RH was a gift from Dr. J. Sandow, Hoechst AG, Frankfurt.
RESULTS The treatment with Pimozide of adult intact male rats for 5 days did not alter the basal serum LH levels. The release of LH after stimulation with LH-RH was significantlydecreased in Pimozide treated rats (p < 0.001) (Fig. 1). The factorial variance test demonstrated that interaction of Pimozide and LH-RH was highly significant (Table 1). The hypophyseal LH concentration in Pimozide treated rats was significantly higher than in control animals ( p < 0.001) (Fig. 2). Pimozide increased prolactin serum levels almost fourfold: Pimozide treated group 190.2 k 12.5 ng/ml, n = 20 as compared to control group 49.7 & 2.6 ng/m (p < 0.001). DISCUSSION These results indicate that the treatment with Pimozide can affect the release of LH in response to LH-RH and can modify pituitary LH concentration. This study confirms
1251
"
T
CONTROL
PlMOZlDE
FIGURE 1. Effect of Pimozide on serum LH levels before and after LH-RH stimulation in adult male rats.
Effect of Pimozide on LH-RH in Adult Male Rats 137
200 1
T
Downloaded by [Australian National University] at 21:43 08 June 2016
FIGURE 2. Effect of Pimozide on pituitary LH concentration in adult male rats.
the results obtained by Debeljuk et al. [4] on pituitary cultured cells in vitro where Pimozide did not alter basal secretion of LH but inhibited the response to LH-RH. Choubhury et al. [2] showed that the administration of Pimozide to immature female rats treated with HCG decreased the ovarian weight. This work suggested that the blocking of dopaminergic receptors decreased the secretion of gonadotropins. Dopamine has an inhibitory role in the control of prolactin release [8, 111 and DA antagonists increase prolactin secretion [6, 12,151. Our results confirm previous findings that blocking of DA receptors increases serum prolactin levels and also indicate that Pimozide in the dose administered was indeed effective. Neurotransmitters intervene at each of the hypothalamic or extrahypothalamic levels responsible for hormonal control [9]. Fuxe [5] demonstrated that the tubero-infundibular DA neurons to the lateral palisade zone can probably inhibit the secretion of LH via an inhibitory axo-axonic influence on the LH-RH containing nerve terminals. The report by Corbin et al. [3] also described a rise in SME-GnRH activity when hypophysectomized rats were treated with Pimozide, suggesting that this drug can inhibit the release of hypothalamic Gn-RH. Beattie et al. [l] described a reduction of proestrum LH in Pimozide treated rats. Leppaluoto et al. 1101 reported reduced LH values in serum after Pimozide treatment in humans and could not detect any changes of LH response to synthetic LH-RH. Therefore, blocking of DA receptors at hypothalamic and pituitary levels could explain the increased pituitary concentration of LH after treatment with Pimozide. The diminished response to exogenous administration of LH-RH could be due to altered sensitivity or alteration in the release mechanism of the pituitary cells in the presence of Pimozide.
Acknowledgments. The authors thank Dr. Niswender and Dr. Reichert and NIAMDD, Bethesda, for gifts of the reagents used in the radioimmunoassays, and to Johnson &Johnson Laboratories for their support.
138 V. Rettori, S. Goijman, and R. Rozados REFERENCES 1. Beattie CW, Gluckman MI, Corbin A (1976): A
2.
Downloaded by [Australian National University] at 21:43 08 June 2016
3.
4.
5.
6.
7.
8.
comparison of a-p-utyrolactone and pimozide on serum gonadotropins and ovulation in the rat. Proc SOCExp Biol Med 153: 147-150 Choubhury SAR, Sharpe RM, Brown PS (1973): Pituitary follicle-stimulating hormone activity in rats treated with apomorphine pimozide, and drugs that modify catecholamine levels. Neuroendocrinology 12: 272-283 Corbin A, Beattie CW, Upton GV (1975): Effect of pimozide, a dopaminergic blocking agent, on hypothalamic luteinizing hormone-releasing hormone activity in hypophysectomized rats. Experientia 31: 613-614 Debeljuk 1, Kher A and Jutisz M (1978): Effect of pimozide and sulpiride on the release of LH and FSH by pituitary cells in culture. Mol Cell Endocr 10: 159-202 Fuxe K, Anderson K, Hokfelt T (1978): Prolactin-monoamine interactions in rat brain and their importance in regulation of LH and prolactin secretion. In: Progress in Prolactin Physiology and Pathology, Robyn C and Harter M (Eds.). Amsterdam: ElseviedNorth-Holland, pp 95- 109 Enjalbert A, Ruberg A, Kordon C (1978): Neuroendocrine control of prolactin secretion. In: Progress in Prolactin Physiology and Pathology, Robyn C and Harter M (Eds.). Amsterdam: ElseviedNorth-Holland, pp 83-94 Janssen P, Brugmans J, Dony J, Shuermans V (1972): An international double-blind clinical evaluation of pimozide. J Clin Pharmac 12: 26-34 Kamberi IA, Mica1 RS, Porter JC (1970): Effect of anterior pituitary perfusion and intraventricu-
9.
10.
11.
12.
13.
14.
15.
16.
lar injection of catecholamines and indoleamines on LH release. Endocrinology 87: 1- 12 Kordon C, Glowinski J (1972): Roles of hypothalamic monoaminergic neurons in the gonadotropin release in healthy women by pimozide and fusaric acid. Acta endocrinologica 81: 455-460 Leppaluoto J, Mannisto P, Ranta T, Linnoila M (1976): Inhibition of mid-cycle gonadotropin release in healthy women by pimozide and fusaric acid. Acta Endocr 81: 455-460 Lu KH, Amenomori Y, Chen CL, Meites J (1970): Effects of central acting drugs on serum and pituitary prolactin levels in rats. Endocrinology 87: 667-672 McLeod RM, Lehmeyer JE (1974): Studies on the mechanism of the dopamine-mediated inhibition of prolactin secretion. Endocrinology 94: 1077- 1085 Niswender GD, Midgley AR, Monroe SE, Reichert LE (1968): Radioimmunoassay for rat luteinizing hormone with anti-ovine LH serum and ovine LH (IS1I). Proc SOC Exp Biol Med 136: 1115-1118 Ojeda SR, Harms PG,McCann SM (1974): Effect of blockade of dopaminergic receptors on prolactin and LH release: Median eminence and pituitary sites of action. Endocrinology 94: 1650- 1657 Quijada M, Illner P, Krulech L, McCann SM (1974): The effect of catecholamines on hormone release from anterior pituitaries and ventral hypothalami incubated in vitro. Neuroendocrinology 13: 151-163 Snedecor GW, Cochran WG (Eds.) (1967): Factorial Experiments. In: Statistical methods. Ames. Iowa: Iowa State University Press, pp 339-380
ISSN: 0148-5016 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/iaan19
Effect of pimozide on the response of LH-RH in intact adult male rats V. Rettori, S. Goijman & R. Rozados To cite this article: V. Rettori, S. Goijman & R. Rozados (1979) Effect of pimozide on the response of LH-RH in intact adult male rats, Archives of Andrology, 3:2, 135-138, DOI: 10.3109/01485017908985060 To link to this article: http://dx.doi.org/10.3109/01485017908985060
Published online: 09 Jul 2009.
Submit your article to this journal
Article views: 3
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iaan19 Download by: [Australian National University]
Date: 08 June 2016, At: 21:43
Effect of Pimozide on the Response of LH-RH in Intact Adult Male Rats
V. RETTORI,S. GOIJMAN, and R. ROZADOS
Downloaded by [Australian National University] at 21:43 08 June 2016
The effect of Pimozide on serum and pituitary concentration of LH was studied in adult male intact rats. Also the release of LH under stimulation of exogenous LH-RH was measured. The treatment for 5 days with pimozide did not alter the serum LH levels, decreased the release of LH by exogenous LH-RH stimulation, and increased the pituitary LH concentration. These results would indicate that blocking the dopaminergic receptors alters pituitary LH release mechanism. Key Words: Pimozide; Dopamine receptors; Pituitary; Gonadotropins; LH-RH.
INTRODUCTION
Pimozide, a clinically effective neuroleptic drug that specifically blocks dopaminergic receptors [7], increases serum prolactin levels in rats [ 141. This drug is also able to alter serum gonadotropin levels in rats [ 1,141 and humans [ 101, and to inhibit the release of LH by LH-RH but it does not alter the basal release of LH in a culture of dispersed rat anterior pituitary cells [4]. The present investigation was undertaken to study the effect of Pimozide on serum and pituitary LH levels in intact adult male rats, and the release of LH by exogenously administered LH-RH in animals treated with Pimozide. Prolactin levels were also measured. MATERIAL AND METHODS Forty male rats of the Wistar strain (mean weight 250 g) were maintained on a diet of laboratory chow, vegetables, and water ad libidum. The photoperiod was 14 hr light every 24 hr. One group of 20 rats were injected subcutaneously for 5 days with 15 mgl100 g/day of Pimozide dissolved in 0.1 M tartaric acid. Another group of 20 rats was injected with vehicle (0.1 M tartaric acid) also for 5 days. On the 5th day the rats treated with Pimozide or with the control vehicle were injected with LH-RH (dissolved in 0.2 ml acidified saline) I.V. at a dose of 100 mglrat or with 0.2 ml acidified saline alone. Twenty minutes after the injection of LH-RH or acidified saline, the rats were sacrificed by decapitation. Blood was collected from the trunk and the serum was separated by centrifugation and kept frozen until assayed. The pituitary glands were dissected free from the neural lobe, weighed, homogenized in saline and kept frozen. Levels of LH were measured by the double antibody method [ 131. An ovine LH preparation was used for labelling with The first antibody was an antiovine L H serum. NIAMDD-Rat-LH RPl was used as the standard preparation. Received April 1979; revised June 11, 1979. From the Centro de Investigaciones en Reproduccion, Buenos Aires, Argentina. Address reprint requests to: V. Rettori, Centro de Investigaciones en Reproduccion, Facultad de Medicina, Paraguay 2155 piso 10, 1121 Buenos Aires, Argentina.
135 D Elsevier North Holland, Inc.. ARCHIVES OF ANDROLOGY 3, 135-138 (1979)
o14a~o1~~/o6o13~~oo4/5o2.25
136
V. Rettori, S. Goijman, and R. Rozados TABLE 1 The Inhibitory Effect of Pimozide on LH-RH Induced Release of RH as Analyzed by the Factorial Variance Test
fv
d.
OF
between animals pimozide LH-RH interaction pim. LH-RH
9 1
I 1
F
SIGNIF. N.S.
0.95 (7.14) (119.4) 10.5
p p p
< 0.05 Q
0.0001
< 0.01
27
error
Downloaded by [Australian National University] at 21:43 08 June 2016
f.
The prolactin was measured by radioimmunoassay using the NIAMDD rat prolactin RPl. The results were evaluated statistically by means of Student's t Test and Factorial approach to Analysis of Variance [16]. Pimozide (1(-4,4,-bis(p-fluorophenyl)butyl-4-piperidyl)-2-benzimidazolinone) was a gift from Johnson & Johnson Laboratories and LH-RH was a gift from Dr. J. Sandow, Hoechst AG, Frankfurt.
RESULTS The treatment with Pimozide of adult intact male rats for 5 days did not alter the basal serum LH levels. The release of LH after stimulation with LH-RH was significantlydecreased in Pimozide treated rats (p < 0.001) (Fig. 1). The factorial variance test demonstrated that interaction of Pimozide and LH-RH was highly significant (Table 1). The hypophyseal LH concentration in Pimozide treated rats was significantly higher than in control animals ( p < 0.001) (Fig. 2). Pimozide increased prolactin serum levels almost fourfold: Pimozide treated group 190.2 k 12.5 ng/ml, n = 20 as compared to control group 49.7 & 2.6 ng/m (p < 0.001). DISCUSSION These results indicate that the treatment with Pimozide can affect the release of LH in response to LH-RH and can modify pituitary LH concentration. This study confirms
1251
"
T
CONTROL
PlMOZlDE
FIGURE 1. Effect of Pimozide on serum LH levels before and after LH-RH stimulation in adult male rats.
Effect of Pimozide on LH-RH in Adult Male Rats 137
200 1
T
Downloaded by [Australian National University] at 21:43 08 June 2016
FIGURE 2. Effect of Pimozide on pituitary LH concentration in adult male rats.
the results obtained by Debeljuk et al. [4] on pituitary cultured cells in vitro where Pimozide did not alter basal secretion of LH but inhibited the response to LH-RH. Choubhury et al. [2] showed that the administration of Pimozide to immature female rats treated with HCG decreased the ovarian weight. This work suggested that the blocking of dopaminergic receptors decreased the secretion of gonadotropins. Dopamine has an inhibitory role in the control of prolactin release [8, 111 and DA antagonists increase prolactin secretion [6, 12,151. Our results confirm previous findings that blocking of DA receptors increases serum prolactin levels and also indicate that Pimozide in the dose administered was indeed effective. Neurotransmitters intervene at each of the hypothalamic or extrahypothalamic levels responsible for hormonal control [9]. Fuxe [5] demonstrated that the tubero-infundibular DA neurons to the lateral palisade zone can probably inhibit the secretion of LH via an inhibitory axo-axonic influence on the LH-RH containing nerve terminals. The report by Corbin et al. [3] also described a rise in SME-GnRH activity when hypophysectomized rats were treated with Pimozide, suggesting that this drug can inhibit the release of hypothalamic Gn-RH. Beattie et al. [l] described a reduction of proestrum LH in Pimozide treated rats. Leppaluoto et al. 1101 reported reduced LH values in serum after Pimozide treatment in humans and could not detect any changes of LH response to synthetic LH-RH. Therefore, blocking of DA receptors at hypothalamic and pituitary levels could explain the increased pituitary concentration of LH after treatment with Pimozide. The diminished response to exogenous administration of LH-RH could be due to altered sensitivity or alteration in the release mechanism of the pituitary cells in the presence of Pimozide.
Acknowledgments. The authors thank Dr. Niswender and Dr. Reichert and NIAMDD, Bethesda, for gifts of the reagents used in the radioimmunoassays, and to Johnson &Johnson Laboratories for their support.
138 V. Rettori, S. Goijman, and R. Rozados REFERENCES 1. Beattie CW, Gluckman MI, Corbin A (1976): A
2.
Downloaded by [Australian National University] at 21:43 08 June 2016
3.
4.
5.
6.
7.
8.
comparison of a-p-utyrolactone and pimozide on serum gonadotropins and ovulation in the rat. Proc SOCExp Biol Med 153: 147-150 Choubhury SAR, Sharpe RM, Brown PS (1973): Pituitary follicle-stimulating hormone activity in rats treated with apomorphine pimozide, and drugs that modify catecholamine levels. Neuroendocrinology 12: 272-283 Corbin A, Beattie CW, Upton GV (1975): Effect of pimozide, a dopaminergic blocking agent, on hypothalamic luteinizing hormone-releasing hormone activity in hypophysectomized rats. Experientia 31: 613-614 Debeljuk 1, Kher A and Jutisz M (1978): Effect of pimozide and sulpiride on the release of LH and FSH by pituitary cells in culture. Mol Cell Endocr 10: 159-202 Fuxe K, Anderson K, Hokfelt T (1978): Prolactin-monoamine interactions in rat brain and their importance in regulation of LH and prolactin secretion. In: Progress in Prolactin Physiology and Pathology, Robyn C and Harter M (Eds.). Amsterdam: ElseviedNorth-Holland, pp 95- 109 Enjalbert A, Ruberg A, Kordon C (1978): Neuroendocrine control of prolactin secretion. In: Progress in Prolactin Physiology and Pathology, Robyn C and Harter M (Eds.). Amsterdam: ElseviedNorth-Holland, pp 83-94 Janssen P, Brugmans J, Dony J, Shuermans V (1972): An international double-blind clinical evaluation of pimozide. J Clin Pharmac 12: 26-34 Kamberi IA, Mica1 RS, Porter JC (1970): Effect of anterior pituitary perfusion and intraventricu-
9.
10.
11.
12.
13.
14.
15.
16.
lar injection of catecholamines and indoleamines on LH release. Endocrinology 87: 1- 12 Kordon C, Glowinski J (1972): Roles of hypothalamic monoaminergic neurons in the gonadotropin release in healthy women by pimozide and fusaric acid. Acta endocrinologica 81: 455-460 Leppaluoto J, Mannisto P, Ranta T, Linnoila M (1976): Inhibition of mid-cycle gonadotropin release in healthy women by pimozide and fusaric acid. Acta Endocr 81: 455-460 Lu KH, Amenomori Y, Chen CL, Meites J (1970): Effects of central acting drugs on serum and pituitary prolactin levels in rats. Endocrinology 87: 667-672 McLeod RM, Lehmeyer JE (1974): Studies on the mechanism of the dopamine-mediated inhibition of prolactin secretion. Endocrinology 94: 1077- 1085 Niswender GD, Midgley AR, Monroe SE, Reichert LE (1968): Radioimmunoassay for rat luteinizing hormone with anti-ovine LH serum and ovine LH (IS1I). Proc SOC Exp Biol Med 136: 1115-1118 Ojeda SR, Harms PG,McCann SM (1974): Effect of blockade of dopaminergic receptors on prolactin and LH release: Median eminence and pituitary sites of action. Endocrinology 94: 1650- 1657 Quijada M, Illner P, Krulech L, McCann SM (1974): The effect of catecholamines on hormone release from anterior pituitaries and ventral hypothalami incubated in vitro. Neuroendocrinology 13: 151-163 Snedecor GW, Cochran WG (Eds.) (1967): Factorial Experiments. In: Statistical methods. Ames. Iowa: Iowa State University Press, pp 339-380
