Catecholaminergic responses in vas deferens isolated from rats submitted to acute swimming stress

Adrenergic response patterns in vas deferens isolated from rats under diurnal rhythms

The aim of this study was to verify, by means of functional methods, whether the circadian rhythm changes adrenergic response patterns in the epididymal half of the vas deferens isolated from control rats as well as from rats submitted to acute stress. The experiments were performed at 9:00 a.m., 3:00 p.m., 9:00 p.m., and 3:00 a.m. The results showed a light-dark dependent variation of the adrenergic response pattern on organs isolated from control as well as from stressed rats. In the control group, only the phenylephrine sensitivity was changed throughout the circadian rhythm. Under the stress condition, both norepinephrine and phenylephrine response patterns were changed, mainly during darkness. The maximal contractile response to both alpha- and beta-agonist and alpha1-agonist was increased in the dark phase, corresponding to high plasmatic concentrations of endogenous melatonin. The vas deferens isolated from stressed rats during the light phase simultaneously incubated with exogenous melatonin showed the same pattern of response obtained in the dark phase, thus indicating a peripheric action of melatonin on this organ. Therefore, the circadian rhythms are important to the adrenergic response pattern in rat vas deferens from both control and stressed rats. In conclusion, we suggest a melatonin modulation on alpha1-postsynaptic adrenergic response in the rat vas deferens.

Puberty installation and adrenergic response of seminal vesicle from rats exposed prenatally to hydrocortisone

We investigated the effects of hydrocortisone during the prenatal period and its repercussion on puberty installation and adrenergic response of seminal vesicle in adult rats. The efficacy of the hydrocortisone treatment in reducing adrenal wet weight immediately after delivery in both the treated mothers and respective pups at birth may indicate impairment of the hypothalamus--pituitary--adrenal axis. This parameter was unchanged in the adult phase of these descendants, suggesting recuperation of this axis. In addition, the treatment with hydrocortisone delayed the age of puberty installation, probably by absence of both physiologic production and liberation of luteinizing hormone and testosterone. Despite the significant reduction in testosterone level as well as of wet weights of both vas deferens and testis in the adult phase, no difference was observed in the sensitivity of the seminal vesicle to the studied sympathetic agonist. However, the observed reduction in contractile response of the seminal vesicle may be a consequence of contractile-system damage in this organ. It is possible that this alteration may cause a reduction in the amount of vesicular secretion so important in the process of ejaculation. In conclusion, these results suggest that administration of hydrocortisone in late prenatal life did not influence the hypothalamus--pituitary--adrenal axis in adult life, although it altered the hypothalamus--pituitary--gonadal axis, and reduced testosterone production starting at puberty, as a consequence of an incomplete masculinization of the hypothalamus plus a reduction in the contractile response of the seminal vesicle.

Effects of restraint stress on responsiveness of atria and vas deferens in Sprague-Dawley rats

1 The effects of stress in rats were evaluated by measuring changes in body weight and in responsiveness to noradrenaline (NA) in the isolated vas deferens and atria after the animals had been exposed to restraint or restraint and isolation. 2 Animals which were subjected to restraint alone (1 h day-1 for 3, 7 or 28 days) had a significantly reduced rate of body weight gain. This effect was not potentiated by the additional stress of isolation. 3 Restraint alone did not produce significant changes in the responsiveness of the vas deferens to NA. However, adding isolation to restraint, as an additional stress, produced a further leftward shift of the NA dose-response curve for the vas deferens, so that there was a significant increase in sensitivity compared with control. 4 There was a significant rightward shift in the NA dose-response curves or reduction in sensitivity in the atria from animals which had been restrained for 7 or 28 days. Isolation did not produce a further rightward shift in the NA dose-response curve. 5 The results from this study indicate that the stress associated with repeated restraint reduces the rate of weight gain and reduces the responsiveness of the atria to NA. The responsiveness of the vas deferens to NA was increased by stress, but the combined effect of isolation and restraint was required to produce a significant effect. The differences in the effects of stress on these tissues could be associated with differences in presynaptic receptor populations.

The importance of androgen on noradrenergic responses of vas deferens isolated from acutely stressed rats

This study investigated the importance of androgen on responses to alpha and beta (norepinephrine) and alpha(1)(phenylephrine and methoxamine) agonists in vasa deferentia isolated from adult, immature, cryptorchid, and castrated rats submitted to swimming-induced acute stress. The participation of adrenergic nervous terminals was also investigated. Acute stress was shown to induce a significant subsensitivity to norepinephrine only in vas deferens from adult rats with normal levels of androgens. In addition, sympathetic denervation of the vas deferens prevented the appearance of subsensitivity. Subsensitivity was not seen when the experiments were carried out using phenylephrine and methoxamine. This shows that subsensitivity to norepinephrine in this acute stress situation may depend on other factors such as neuronal uptake, but not on alpha(1)-adrenoceptor response. Thus, when animals are exposed to acute stressogenic situations, this subsensitivity requires physiological levels of androgens to establish, and may also be involved in body homeostasis.

Noradrenergic response in vas deferens from rats submitted to acute and repeated stress

1. This work investigated the effects of androgens on the norepinephrine sensitivity of vasa deferentia from rats submitted to acute or repeated stress, as well as the participation of alpha1-adrenoceptors in the response of intact and bisected vasa deferentia from adult normal rats submitted to acute or repeated stress. 2. The acute stress produced subsensitivity to norepinephrine only in intact vasa deferentia from adult normal rats, which was prevented by lack of androgens, suggesting that the sensitivity may be dependent on the physiological level of androgen. 3. No change was observed in intact vas deferens sensitivity to norepinephrine in repeated stress, suggesting the occurrence of adaptation to elevated norepinephrine levels or a mild decrease in androgen levels or both. 4. The changes in sensitivity observed in acute and repeated stress may also be due to alterations in alpha1-adrenergic receptors that are located in the prostatic portion of the vas deferens.