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3.
Braz J Med Biol Res ; 27(7): 1669-72, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7874035

RESUMO

The analgesic response was evaluated by the tail immersion test in adult male (N = 30), female (N = 21) and androgenized female Wistar rats (N = 15). The reaction time for tail withdrawal from the hot water bath was faster for male than for female rats (3.48 +/- 0.12 vs 6.46 +/- 0.42 s). The reaction time of androgenized female rats was similar to that of male rats (3.08 +/- 0.16 s). Blockade of opiate receptors with naloxone (2 mg/kg, ip) decreased the sensitivity to the noxious stimuli in males (4.08 +/- 0.10 s) and in androgenized females (3.69 +/- 0.19 s) but increased it in female rats (5.01 +/- 0.41 s). These data show sex-related differences in the analgesic response evaluated by the tail immersion test and indicate that administration of androgens to newborn female rats affects their pain sensitivity.


Assuntos
Naloxona/farmacologia , Caracteres Sexuais , Cauda/efeitos dos fármacos , Analgesia , Animais , Feminino , Masculino , Naloxona/administração & dosagem , Medição da Dor/efeitos dos fármacos , Ratos , Ratos Wistar , Tempo de Reação , Testosterona/administração & dosagem , Testosterona/farmacologia
4.
Braz. j. med. biol. res ; 27(7): 1669-1672, Jul. 1994.
Artigo em Inglês | LILACS | ID: lil-319776

RESUMO

The analgesic response was evaluated by the tail immersion test in adult male (N = 30), female (N = 21) and androgenized female Wistar rats (N = 15). The reaction time for tail withdrawal from the hot water bath was faster for male than for female rats (3.48 +/- 0.12 vs 6.46 +/- 0.42 s). The reaction time of androgenized female rats was similar to that of male rats (3.08 +/- 0.16 s). Blockade of opiate receptors with naloxone (2 mg/kg, ip) decreased the sensitivity to the noxious stimuli in males (4.08 +/- 0.10 s) and in androgenized females (3.69 +/- 0.19 s) but increased it in female rats (5.01 +/- 0.41 s). These data show sex-related differences in the analgesic response evaluated by the tail immersion test and indicate that administration of androgens to newborn female rats affects their pain sensitivity.


Assuntos
Animais , Masculino , Feminino , Ratos , Caracteres Sexuais , Naloxona , Cauda , Analgesia , Medição da Dor/efeitos dos fármacos , Naloxona , Ratos Wistar , Tempo de Reação , Testosterona
5.
Braz J Med Biol Res ; 25(9): 951-5, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1342843

RESUMO

Mean arterial pressure and heart rate were determined in conscious, unrestrained groups of 10 male, female and androgenized female Wistar rats 20 s (early pressor response) and 1 min (late sustained response) after bilateral carotid artery occlusion. The early pressor response, which is of carotid reflex origin, was 40% greater in female than in male rats (45 +/- 2 vs 63 +/- 3 mmHg, respectively). The late sustained response, which is of central origin (probably ischemic), did not differ between male and female rats (32 +/- 2 vs 37 +/- 4 mmHg, respectively). The magnitude of the early pressor response of androgenized female rats (50 +/- 2 mmHg) was similar to that of male rats (45 +/- 2 mmHg) but the late sustained response was 19% smaller (26 +/- 2 mmHg). Common carotid occlusion caused increases in heart rate which were greater in female (51 +/- 9 and 34 +/- 9 beats/min in the early pressor response and late sustained response, respectively) than in male rats (31 +/- 5 and 8 +/- 4 beats/min, respectively). In androgenized female rats, heart rate decreased during common carotid occlusion (34 +/- 7 and 35 +/- 8 beats/min after 20s and 1 min, respectively). These data provide evidence that there are substantial sex-related differences in the cardiovascular responses to common carotid occlusion in conscious rats and indicate that administration of androgens to newborn female rats affects the baroreceptor reflex control of their arterial pressure.


Assuntos
Fenômenos Fisiológicos Cardiovasculares , Artéria Carótida Primitiva/fisiologia , Estado de Consciência/fisiologia , Caracteres Sexuais , Animais , Constrição , Estro/fisiologia , Feminino , Hemodinâmica/fisiologia , Masculino , Ratos , Ratos Wistar , Fatores de Tempo
6.
Braz. j. med. biol. res ; 25(9): 951-5, 1992. ilus
Artigo em Inglês | LILACS | ID: lil-113598

RESUMO

Mean arterial pressure and heart rate were determined in conscious, unrestrained groups of 10 male, female and androgenized female Wistar rats 20 s (early pressor response) and 1 min (late sustained response) after bilateral carotid artery occlusion. The early pressor response, which is carotid reflex origin, was 40% greater in female than in male rats (45 ñ 2 vs 63 ñ 3 mmHg, respectively). The late sustained response, which is of central origin (probably ischemic), did not differ between male and female rats (32 ñ 2 vs 37 ñ 4 mmHg, respectively). The magnitude of the early pressor response of androgenized female rats (50 ñ 2 mmHg) was similar to that of male rats (45 ñ 2 mmHg) but the late sustained response was 19% smaller (26 ñ 2 mmHg). Common carotid occlusion caused increases in haert rate which were greater in female (51 ñ 9 and 34 ñ 9 beats/min in the early pressor response and late sustained response respectively) than in male rats (31 ñ 5 and 8 ñ 4 beats/min, respectively). In androgenized female rats, heart rate decreased during common carotid occlusion (34 ñ 7 and 35 ñ 8 beats/min after 20 s and 1 min, respectively). These data provide evidence that there are substantial sex-related differences in the cardiovascular responses to common carotid occlusion in conscoious rats and indicate that administration of androgens to newborn female rats affects the baroreceptor reflex control of their arterial pressure


Assuntos
Ratos , Androgênios/administração & dosagem , Pressão Arterial , Caracteres Sexuais , Trombose das Artérias Carótidas , Frequência Cardíaca , Pressorreceptores , Fatores Sexuais
7.
Braz J Med Biol Res ; 24(9): 961-5, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1797293

RESUMO

The influence of testosterone on the development of the pressor response to common carotid occlusion was investigated in control and median eminence-lesioned male rats. In control rats (N = 9), gonadectomy performed 21 days before the experiments reduced by 22% (from 51 +/- 2 to 40 +/- 2 mmHg) and treatment with testosterone (300 micrograms for 4 days before the measurements) increased the initial peak pressor response (from 51 +/- 2 to 57 +/- 2 mmHg) which depends on carotid innervation. The maintained response which is of central origin (probably ischemic) was less affected. In nongonadectomized rats (N = 6), lesions of median eminence (6 days) decreased the initial peak by 19% (from 52 +/- 2 to 42 +/- 3 mmHg) and the maintained response by 56% (from 32 +/- 2 to 14 +/- 1 mmHg). Sham-operated rats served as controls. In gonadectomized animals (N = 6) the lesion reduced only the maintained response (from 23 +/- 2 to 11 +/- 1 mmHg). Testosterone supplementation restored the maintained response but did not alter the initial peak. These results indicate that the pressor response to common carotid occlusion in male rats is modulated by testosterone and that the depression in the maintained response caused by median eminence lesion can be reversed by steroid supplementation.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Eminência Mediana/fisiologia , Testosterona/farmacologia , Animais , Artérias Carótidas/cirurgia , Constrição , Masculino , Orquiectomia , Ratos , Ratos Endogâmicos
8.
Braz J Med Biol Res ; 24(12): 1261-4, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1668874

RESUMO

The involvement of opioid receptors in the analgesic response was evaluated by the tail-immersion test in simultaneously adrenalectomized and ovariectomized female Wistar rats (210-250 g). The reaction time (mean +/- SEM) for tail withdrawal from hot water decreased significantly 2 weeks after surgery (3.52 +/- 0.20 s) when compared to intact animals (6.09 +/- 0.23 s). Hormonal replacement with dexamethasone (50 micrograms/day) did not affect reaction time (3.38 +/- 0.19 s). However, this response was restored by combined adrenal and gonadal steroid substitution (estradiol 5 micrograms/day and progesterone 1.5 micrograms 6 h before the tests) therapy (5.11 +/- 0.45 s in animals treated with dexamethasone plus estradiol and 5.04 +/- 0.43 s in animals treated with dexamethasone plus estradiol plus progesterone). Naloxone (2 mg/kg) decreased the reaction time of animals treated with adrenal and gonadal steroids (5.11 +/- 0.45 vs 4.15 +/- 0.44 s and 5.04 +/- 0.43 vs 3.87 +/- 0.28 s, respectively, before and after naloxone) but failed to decrease it in rats treated with dexamethasone only (3.88 +/- 0.18 vs 4.34 +/- 0.25 s, before and after naloxone). These observations indicate that gonadal steroids are the most important steroid factors involved in the reaction time to tail immersion in hot water and confirm other reports that the opioid pathways modulating the neuronal circuitry require the presence of these hormones.


Assuntos
Dexametasona/farmacologia , Estradiol/farmacologia , Naloxona/farmacologia , Medição da Dor/efeitos dos fármacos , Progesterona/farmacologia , Tempo de Reação/efeitos dos fármacos , Receptores Opioides/efeitos dos fármacos , Glândulas Suprarrenais/fisiologia , Animais , Endorfinas/antagonistas & inibidores , Endorfinas/farmacologia , Feminino , Ovário/fisiologia , Ratos , Ratos Wistar , Tempo de Reação/fisiologia , Cauda/efeitos dos fármacos , Fatores de Tempo
9.
Braz J Med Biol Res ; 24(10): 1059-62, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1665725

RESUMO

The effect of tubero-infundibular dopaminergic neurons (TIDA) on the release of prolactin (PRL) and alpha-melanocyte stimulating hormone (alpha-MSH) was studied in median eminence-lesioned (MEL) male rats (N = 6-28). Plasma PRL and alpha-MSH levels were significantly elevated 2 (86.1 +/- 19.8 and 505.1 +/- 19.1 ng/ml), 4 (278.7 +/- 15.5 and 487.4 +/- 125.1 ng/ml), 7 (116.2 +/- 16.2 and 495.8 +/- 62.6 ng/ml) and 14 (247.3 +/- 26.1 and 448.4 +/- 63.8 ng/ml) days after MEL when compared to sham-operated control animals (55.5 +/- 13.4 and 56.2 +/- 6.1 ng/ml, respectively). MEL altered plasma PRL and alpha-MSH levels in a differential manner, with a 1.5- to 5.0-fold increase in PRL and an 8.0- to 9.0-fold increase in alpha-MSH. The increase of alpha-MSH levels occurred abruptly and remained constant from days 2 to 14. These observations indicate that TIDA plays an important role in the pituitary release of PRL and alpha-MSH and provide evidence that the release of the two hormones occurs in a differential manner.


Assuntos
Eminência Mediana/fisiologia , Neurônios/fisiologia , Prolactina/metabolismo , alfa-MSH/metabolismo , Animais , Masculino , Prolactina/sangue , Ratos , Ratos Endogâmicos , alfa-MSH/sangue
10.
Braz. j. med. biol. res ; 24(10): 1059-62, 1991. ilus
Artigo em Inglês | LILACS | ID: lil-102089

RESUMO

The effect of tubero-infundibular dopaminergic neurons (TIDA) on the release of prolactin (PRL) and alpha-melanocyte stimulating hormone (alpha-MSH) was studied in median eminence-lesioned (MEL) male rats (N = 6-28). Plasma PRL and alpha-MSH levels were significantly elevated 2(86.1 ñ 19.8 and 505.1 ñ 19.1 ng/ml), 4(278.7 ñ 15.5 and 487.4 ñ 125.1 ng/ml), 7 (116.2 ñ 16.2 and 495.8 ñ 62.6 ng/ml) and 14 (247.3 ñ 26.1 and 448.4 ñ 63.8 ng/ml) days after MEL when compared to sham-operated control animals (55.5 ñ 13.4 and 56.2 ñ 6.1 ng/ml, repectively). MEL altered plasma PRL and alpha-MSH levels in a diffential manner, with 1.5-to5.0-fold increase in PRL and an 8.0- to 9.0-fold increase in alpha-MSH. The increase of alpha-MSH levels occured abruptly and remained constant from days 2 to 14. These observations indicate that TIDA plays an important role in the pituitary release of PRL and alpha-MSH and provide evidence that the release of the two hormones occurs in a differential manner


Assuntos
Animais , Masculino , Ratos , alfa-MSH/metabolismo , Eminência Mediana/fisiologia , Neurônios/fisiologia , Prolactina/metabolismo , alfa-MSH/sangue , Prolactina/sangue , Ratos Endogâmicos
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