Effects of Angiotensin II Microinjected into Medial Amygdala on Male Sexual Behavior in Rats (original) (raw)
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Behavioural Brain Research, 2010
Stress might influence the reproductive behavior in females, and central angiotensin II (Ang II) is a peptide that plays a role in stress response and in the modulation of sexual behavior. The medial amygdala (MeA), an important structure that regulates this behavior, is strongly involved in stress response. The aim of the present study was to evaluate the effect of acute restraint stress on the night of proestrus on sexual receptivity in female rats and the participation of Ang II and MeA in this effect. Adult female Wistar rats with regular estrous cycles were utilized. The acute stress protocol utilized was the restraint stress for 15 min on the night of proestrus. The participation of Ang II was evaluated by injecting Ang II and Ang II receptor antagonists (losartan and PD12319) into the MeA. The lordosis quotient was recorded. The stress or the microinjection of Ang II into the MeA significantly reduced sexual behavior. The blockade of AT 1 or AT 2 receptors in the MeA prevented the effect of stress and the effect of Ang II microinjection into this nucleus on sexual receptivity. We concluded that acute restraint stress on the night of proestrus reduces sexual behavior in rats, and this effect is mediated by both AT 1 and AT 2 receptors in the MeA.
Pathophysiological role of the renin-angiotensin system on erectile dysfunction
European Journal of Clinical Investigation, 2013
Background The renin-angiotensin system (RAS) has been shown to play an active role within the erectile tissues. The aim of this narrative review is to summarize the literature addressing the pathophysiological role of RAS on erectile function. Additionally, we update evidence on recent findings on the role of the Ang-(1-7) and Mas receptor on the erectile function and its therapeutic potential for treating erectile dysfunction (ED).
Pharmacological analysis of male rat sexual behavior
Neuroscience & Biobehavioral Reviews, 1987
Pharmacological influences on male rat sexual behavior are reviewed m an attempt to tdentify neurotransmitters and their respective receptor types that regulate various factors comprising the behavmral pattern. Evidence is presented that" (1) serotonerg~c influence is generally inhibitory to sexual behavtor, although two receptor subtypes may lower ejaculatmn threshold, (2) dopammerg~c agomsts faohtate several aspects of copulatory behavmr and ea c optda gemtal responses; (3) noradrenerglc activity appears to increase sexual arousal; (4) cholinerglc agomsts facditate ejaculatton, or m some cases, delay or prevent ruination of copulation, (5) GABA agomsts mh~b~t sexual responses both ill and ex coptda, (6) opmte agonists appear to inhibit copulatmn and pemle reflexes, although antagomsts have mixed effects, (7) ACTH and MSH peptides promote copulatory behavmr and gemtal responses, (8) oxytocm facdltates er ~ opula pemle responses, but may contribute to postejaculatory refractoriness, and (9) long-term exposure to prolactm mh~b~ts sexual behavmr and pende responses. Although some progress has been made m tdentffymg neurotransm~tter-receptor effects on behavmral components, copulatory behavtor is complex and no drug has been found to affect only a smgle component Furthermore, drug speclfioty Is only relative
The Journal of Sexual Medicine, 2009
Introduction. The high incidence of erectile dysfunction (ED) in diabetes highlights the need for good treatment strategies. Recent evidence indicates that blockade of the angiotensin type I receptor (AT1) may reverse ED from various diseases. Aim. To explore the role of cavernous renin-angiotensin system (RAS) in the pathogenesis of diabetic ED and the role of losartan in the treatment of diabetic ED. Methods. The AT1 blocker (ARB) losartan (30 mg/kg/d) was administered to rats with streptozocin (65 mg/kg)induced diabetes. Erectile function, cavernous structure, and tissue gene and protein expression of RAS in the corpora cavernosa were studied. Main Outcome Measure. We sought to determine the changes of cavernous RAS in the condition of diabetes and after treatment with losartan. Results. RAS components (angiotensinogen, [pro]renin receptor, angiotensin-converting enzyme [ACE], and AT1) were expressed in cavernosal tissue. In diabetic rats, RAS components were upregulated, resulting in the increased concentration of angiotensin II (Ang II) in the corpora. A positive feedback loop for Ang II formation in cavernosum was also identified, which could contribute to overactivity of cavernous RAS in diabetic rats. Administration of losartan blocked the effect of Ang II, downregulated the expression of AT1 and Ang II generated locally, and partially restored erectile function (losartan-treated group revealed an improved intracavernous pressure/mean systemic arterial pressure ratio as compared with the diabetic group (0.480 Ϯ 0.031 vs. 0.329 Ϯ 0.020, P < 0.01). However, losartan could not elevate the reduced smooth muscle/collagen ratio in diabetic rats. Conclusions. The cavernous RAS plays a role in modulating erectile function in corpora cavernosa and is involved in the pathogenesis of diabetic ED. ARB can restore diabetic ED through downregulating cavernous RAS.
Dopaminergic control of male sex behavior in rats: Effects of an intracerebrally-infused agonist
Brain Research, 1986
Key words: sexual behavior --apomorphine --dopamine --medial preoptic area --caudate-putamen -nucleus accumbens --lateral septum Systemically-administered dopaminergic drugs have been found to facilitate sexual behavior of men and male rats. The present experiments investigated the localization within the brain of dopaminergic effects on copulation of male rats. Apomorphine, a dopamine agonist, was microinfused into the medial preoptic area, caudate-putamen, nucleus accumbens, lateral septum and lateral ventricle. The lowest dose of apomorphine (0.2 pg) infused into the ventricle reduced the number of ejaculations, slowed the rate of intromitting and decreased the percentage of mounts on which the male gained vaginal intromission. The higher two doses (0.5 and 2.0/~g) infused into the medial preoptic area and, in some cases, the ventricle, increased the number of ejaculations and the percentage of mounts with vaginal intromission, increased the rate of intromitting and decreased the latency to ejaculate and the postejaculatory interval before resuming copulation. Infusions into the caudate-putamen and lateral septum were without effect. Those into nucleus accumbens produced only a slight dose-related decrease in latency to begin copulating. The copulatory impairments associated with infusions of the lowest dose into the ventricle may have resulted from stimulation of autoreceptors, or from preferential stimulation by low doses of an undetermined area. The facilitative effects of the two higher doses into the medial preoptic area and lateral ventricle may have been due to stimulation of dopaminergic postsynaptic receptors. 0006-8993/86/$03.50 (~ 1986 Elsevier Science Publishers B.V. (Biomedical Division)
Angiotensin II stimulates sperm motility
Regulatory Peptides, 1996
The physiological factors which induce and maintain mammalian sperm maturation and motility generally remain unclear, although several agents are known to be involved. We recently described the application of immunocytochemical and immunoblotting methods to identify the angiotensin II type 1 (AT1) receptor in the tails of ejaculated rat and human sperm, and gave evidence to show that angiotensin II may promote sperm motility. These data are extended here by the application of a computerised sperm tracking system (the Hobson Sperm Tracker) to demonstrate that AII has actions on specific motility parameters, including curvilinear velocity, straight line velocity, and amplitude of lateral head movement. Since local tissue renin-angiotensin systems are present in both male and female tracts, the data suggest that angiotensin II has a role in the maintenance of sperm function and fertility.
Neuropeptides, 1998
This study determined the effect of the selective angiotensin II (A II) AT 1 receptor subtype antagonist Iosartan in the medial preoptic area (MPOA) of ovariectomized rats, treated with estrogen or untreated, on the release of gonadotropins (LH and FSH) and prolactin (PRL). The MPOA is sensitive to the action of A II and contains cell bodies of neurons producing luteinizing hormone-releasing hormone and a large density of estradiol receptors. Plasma FSH was not altered in any situation. However, Iosartan blocked and estradiol facilitated the stimulating and inhibitory effects of A II microinjection into the MPOA on LH and PRL secretion, respectively. The results indicate that these effects are mediated by AT1 receptors in the MPOA and that estradiol may modulate them. On the other hand, Iosartan itself reduced LH secretion in ovariectomized rats, indicating that the increase in the secretion of this hormone, after removal of the negative feedback caused by estradiol, is due, at least in part, to the action of A II on AT~ receptors of the MPOA.
Physiology & Behavior, 1993
PHYSIOL BEHAV 54(2) 249-258, 1993.--Accumulating evidence indicates that neurokinins play a role in the neural regulation of male rat copulatory behavior. We have previously reported that injections of the neurokinin substance P into the medial preoptic nucleus facilitated male rat copulatory behavior. Recently, a number of other neurokinins, neurokinin K (neuropeptide K), neurokinin A (substance K), and neurokinin 3' (derived from the same gene as substance P), have been identified in the mammalian CNS. Therefore, in a series of experiments we examined the effects on male copulatory behavior following bilateral injections of different doses of neurokinin K (NkK), neurokinin A (NkA), or neurokinin 3" (Nk3") into the medial preoptic area (MPOA), bed nucleus of the stria terminalis (BnST), or the caudate/putamen. Bilateral injections of NkK into the MPOA or BnST inhibited the expression of male copulatory behavior. The most marked effect was seen following bilateral injections of 0.25 and 0.52 nmol of NkK into the MPOA and the BnST. These injections produced a dramatic suppression of copulatory behavior in previously sexually vigorous male rats when compared to control injections. In contrast, bilateral injections of three different doses of NkA into the MPOA failed to affect any parameter of male copulatory behavior. Bilateral injections of 0.431 nmol of Nk3" into the MPOA failed to affect the expression of copulatory behavior, but significantly delayed its initiation when compared to controls. Bilateral injections of 0.251 nmol of NkK into the caudate/putamen had no significant effect on copulatory behavior in sexually vigorous male rats when compared to control injections. The results of the present study provide further support for a role of neurokinins in the regulation of copulatory behavior in the male rat. Taken together, these results suggest that the effects of neurokinins upon the expression of male copulatory behavior are site specific for brain regions in the sexually dimorphic vomeronasal pathway which includes the MeA, BnST, and MPOA.