Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We recently reported that chronic administration of the 5-HT1A receptor agonist, ipsapirone (0.5 milligrams in drinking water for 3 weeks), has anxiolytic activity in the rat. Herein, we investigated whether this treatment promotes tachyphylaxis to the acute neuroendocrine effects of ipsapirone. Rats chronically treated with ipsapirone displayed a 7% decrease in body weights, compared to vehicle-pretreated rats, thereby confirming previous observations. On the other hand, ipsapirone pretreatment did not affect basal plasma levels of adrenocorticotropin (ACTH), corticosterone, prolactin, aldosterone, and renin activity, nor did it affect their respective rises following an acute ipsapirone (50 mg/kg PO) challenge. Moreover, ipsapirone pretreatment did not affect the increase in plasma prolactin levels elicited by the dopaminergic receptor antagonist haloperidol. These results suggest that neither the 5-HT1A receptors nor the catecholamine receptors that mediate ipsapirone acute neuroendocrine effects develop tolerance to stimulation upon sustained ipsapirone treatment.
 ...
PMID:Chronic treatment with an anxiolytic dose of the 5-HT1A agonist ipsapirone does not alter ipsapirone acute neuroendocrine effects. 790 66

The influence of cocaine exposure on serotonergic neurons and postsynaptic 5-HT1A receptor-mediated responses was evaluated by measuring neuroendocrine responses to a serotonin (5-HT) releaser or a 5-HT1A agonist. Male rats received cocaine (15 mg/kg, i.p.) or saline twice daily for 7 days. Forty-two hr after the final cocaine injection, the 5-HT releaser d-fenfluramine (0, 0.2, 0.6, 2, or 5 mg/kg, i.p.) or the 5-HT1A agonist, 8-OH-DPAT (0, 10, 50, 200 or 500 micrograms/kg, s.c.) were administered. Blood samples were then collected for analysis of plasma ACTH, prolactin, and renin concentrations. The ACTH responses to d-fenfluramine and 8-OH-DPAT were inhibited in cocaine pretreated rats. However, the prolactin responses to d-fenfluramine and 8-OH-DPAT were not significantly modified by cocaine exposure. Additionally, the renin response to d-fenfluramine was unaltered by repeated cocaine administration, while 8-OH-DPAT did not alter renin secretion in either pretreatment group. In contrast to published reports which show that cocaine exposure produces supersensitive 5-HT2A and/or 5-HT2C receptor-mediated responses, the present data suggest that repeated cocaine exposure produces subsensitivity to at least some postsynaptic 5-HT1A receptors. Cocaine-induced deficits in the ACTH response to 5-HT releasers may reflect 5-HT1A receptor subsensitivity, but presynaptic deficits cannot be excluded. Examination of the ACTH response to 5-HT1A agonists may represent a valuable approach to determine deficits in 5-HT function in human cocaine abusers.
 ...
PMID:Repeated cocaine exposure inhibits the adrenocorticotropic hormone response to the serotonin releaser d-fenfluramine and the 5-HT1A agonist, 8-OH-DPAT. 798 71

The present study had two objectives: (1) to provide information on neuroendocrine challenge tests that can lead to diagnostic tests in humans; and (2) to confirm our previous observation that chronic fluoxetine selectively inhibits serotonin (5-HT1A) receptor function. We determined the effect of chronic fluoxetine and desipramine (DMI) on the hormone response to ipsapirone, a 5-HT1A agonist and a potential anxiolytic drug. Ipsapirone increased oxytocin, adrenocorticotropic hormone (ACTH), corticosterone, and prolactin, but not renin or vasopressin concentrations in plasma. Chronic fluoxetine, but not DMI, significantly inhibited the effect of ipsapirone on plasma oxytocin, ACTH and corticosterone concentrations. Chronic fluoxetine also reduced the Bmax for 3H-8-hydroxy-2-(dipropylamino) tetralin (3H-8-OH-DPAT) labelled 5-HT1A receptors in the midbrain. Neither antidepressant altered the density or affinity of 5-HT uptake sites. In conclusion, the present results confirm our previous results using 8-OH-DPAT as a challenge, and suggest that chronic 5-HT uptake inhibition results in adaptive changes leading to decreased function of the 5-HT1A receptor system. Finally, because ipsapirone may be administered to humans, it might be usable to evaluate 5-HT1A receptor function in depressed patients.
 ...
PMID:Attenuation of hormone responses to the 5-HT1A agonist ipsapirone by long-term treatment with fluoxetine, but not desipramine, in male rats. 799 56

The present study investigated the consequences of prenatal cocaine exposure on central serotonin (5-HT) 5-HT1A receptor-mediated function in prepubescent male and female progeny. Pregnant rats received saline or cocaine (15 mg/kg s.c.) twice daily from gestational day 13 through 20. All litters were fostered to nontreated lactating dams. Cocaine did not alter weight gain during pregnancy and did not affect progeny weight at birth or at postnatal day 28. Male and female progeny were tested at a prepubescent age (postnatal day 28) by measuring 1) the stimulation of adrenocorticotropic hormone, corticosterone and renin by a maximally effective dose (0.5 mg/kg s.c.) of the 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT); and 2) [3H]8-OH-DPAT-labeled 5-HT1A receptors and [3H]paroxetine-labeled 5-HT uptake sites in hypothalamus, cortex and midbrain. Basal hormone levels were unaffected by prenatal cocaine exposure. However, prenatal cocaine exposure significantly potentiated the adrenocorticotropic hormone (+28%) and renin (+53%) responses to 8-OH-DPAT in male but not female progeny. In contrast, the corticosterone response to 8-OH-DPAT was not significantly altered in either male or female progeny. Likewise, the number of 5-HT1A receptors and 5-HT uptake sites in the cortex, midbrain and hypothalamus were unaffected by prenatal cocaine exposure. These data demonstrate that prenatal cocaine exposure can potentiate brain 5-HT1A receptor-mediated function in progeny and that alterations in hypothalamic 5-HT1A function are gender specific. These data suggest the possibility that prenatal cocaine may increase 5-HT1A receptor function in extrahypothalamic brain regions.
 ...
PMID:Potentiation of 5-HT1A receptor-mediated neuroendocrine responses in male but not female rat progeny after prenatal cocaine: evidence for gender differences. 799 58

This study tested whether a new serotonin (5-HT1B) agonist, 3-(1,2,5,6-tetrahydro-4-pyridyl)-5-propoxy-pyrrolo[3,2-b]pyridine (CP-93,129), could be used to study the potential role of 5-HT1B receptors in the secretion of adrenocorticotropic hormone (ACTH), prolactin, and renin. CP-93,129 has a high affinity for 5-HT1B receptors but low affinity for other 5-HT receptor subtypes. In addition, CP-93,129 does not readily cross the blood-brain barrier. The secretion of ACTH, prolactin, and renin is known to be increased after activation of 5-HT receptors. ICV injections of CP-93,129 (100 micrograms/kg) increased the plasma concentrations of ACTH, prolactin, and renin. CP-93,129 also increased blood pressure and reduced heart rate. To determine whether these effects of CP-93,129 are centrally mediated, we compared them with IP injection of the same dose of CP-93,129. IP-injected CP-93,129 did not alter blood pressure or heart rate and did not elevate plasma prolactin and renin concentrations. To determine whether 5-HT1B receptors mediate the central effects of CP-93,129, rats were pretreated with the 5-HT antagonists l-propranolol or metergoline prior to ICV injections of doses of CP-93,129 (0-100 micrograms/kg). The 5-HT1A/1B/2A/2C antagonist metergoline (0.5 mg/kg, IP) failed to inhibit the CP-93,129-induced elevation of ACTH, prolactin, or renin concentrations. In contrast, the 5-HT1A/1B/beta antagonist l-propranolol (20 micrograms/kg, ICV) inhibited the renin but not the ACTH or prolactin responses to ICV CP-93,129.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:ICV injection of the serotonin 5-HT1B agonist CP-93,129 increases the secretion of ACTH, prolactin, and renin and increases blood pressure by nonserotonergic mechanisms. 809 Aug 11

The present studies determined whether serotonin 5-HT1A receptor-mediated function is modified by chronic exposure to antidepressants. Hormone responses to the 5-HT1A agonist, 8-OH-DPAT, were evaluated after long-term exposure to two antidepressants, the 5-HT uptake blocker, fluoxetine, and the norepinephrine uptake blocker, desipramine (DMI). In addition, the density and affinity of 5-HT1A receptors in the hypothalamus and cerebral cortex were measured. Male rats received fluoxetine (10 mg/kg i.p.), DMI (5 mg/kg i.p.) or saline injections once daily for 21 days. 8-OH-DPAT (0-500 micrograms/kg s.c.) was administered 18 h after the final antidepressant injection and 15 min before sacrifice. 8-OH-DPAT significantly increased plasma ACTH, corticosterone, oxytocin and prolactin, but not renin or vasopressin concentrations. Chronic injections of fluoxetine inhibited the ACTH, corticosterone and oxytocin responses to 8-OH-DPAT, suggesting reduced 5-HT1A receptor function. In contrast, chronic DMI did not alter the hormone responses to 8-OH-DPAT. The density and affinity of 5-HT1A receptors in the frontal cortex or hypothalamus were not altered by either fluoxetine or DMI. To verify that the observed effects require prolonged exposure to fluoxetine, rats received a single injection of fluoxetine (10 mg/kg, i.p.), 3 h before 8-OH-DPAT (0-500 micrograms/kg s.c.). Acute fluoxetine did not reduce any of the hormone responses to 8-OH-DPAT. In conclusion, the results suggest that chronic, but not acute, exposure to fluoxetine decreases 5-HT1A receptor function. This effect is not seen in rats chronically exposed to DMI.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Long-term fluoxetine, but not desipramine, inhibits the ACTH and oxytocin responses to the 5-HT1A agonist, 8-OH-DPAT, in male rats. 811 81

These studies demonstrate that prenatal cocaine produces differential changes in neuroendocrine responses following challenge with a 5-HT releaser versus a 5-HT1A agonist and suggest differential functional alterations in both pre- and postsynaptic components of 5-HT pathways. The attenuated neuroendocrine responses in adult male progeny following challenge with a 5-HT releaser, in the absence of reductions in 5-HT receptors, provide additional evidence in support of a presynaptic 5-HT deficit in adult male cocaine-exposed progeny. Furthermore, since prenatal cocaine produced a differential profile of alterations in 5-HT-mediated neuroendocrine responses in adult male (i.e., decreases ACTH and renin) versus prepubescent female (i.e., decreases ACTH and corticosterone) progeny following challenge with a 5-HT releaser, these data indicate that the differences could be due to gender and/or postnatal developmental ages. Gender differences in prenatal cocaine effects on postsynaptic receptor function were more clearly shown in study II, which demonstrated that at the same postnatal age, 5-HT1A-mediated neuroendocrine responses were significantly potentiated in male but not female cocaine-exposed progeny. In summary, the data presented in this chapter indicate that the biochemical and functional changes in 5-HT systems observed following prenatal exposure to cocaine are unique with respect to pre- versus postsynaptic alterations, pre- versus postpubescent developmental times, and differences between genders. A number of general conclusions can be drawn from the data presented. The presence of marked neurochemical deficits at both pre- and postpubescent timepoints, in the absence of any visually apparent physical terata, emphasizes the importance of investigating the neurochemical teratogenic potential of cocaine and other psychostimulants. Furthermore, data from these studies demonstrate the importance of investigating male and female progeny separately, as prenatal cocaine exposure may produce gender-specific alterations in some, but not all, aspects of brain neurotransmitter systems. Another important point that can be discerned from the present data is the necessity of subjecting cocaine-treated animals to challenge tests in order to reveal alterations that might not be readily apparent from measuring basal values for specific biochemical or functional parameters (e.g., basal hormone levels). In addition, the differential biochemical and functional changes in 5-HT systems, manifested at pre- versus postpubescent times, suggests that prenatal cocaine may adversely affect the normal maturational changes occurring in 5-HT systems. This may be of consequence in evaluating developmental stages in human offspring exposed to cocaine in utero. Furthermore, the ability of prenatal cocaine to alter 5-HT-mediated ACTH and renin responses in progeny suggest that offspring may exhibit alterations in their response to physiologic stimuli such as stress. Since neuroendocrine challenge tests can be performed in humans, the present data indicate the potential clinical utility of this approach to provide peripheral markers that can be used to identify changes in brain 5-HT pathways in human offspring exposed in utero to cocaine. Prenatal cocaine-induced alterations in brain 5-HT systems may be of significant clinical importance as dysfunction of 5-HT systems has been implicated in various psychiatric disorders including depression, anxiety, aggression, and drug-seeking behavior.
 ...
PMID:Prenatal cocaine produces biochemical and functional changes in brain serotonin systems in rat progeny. 859 82

Drugs that, directly or indirectly produce activation of serotonin (5-HT) receptors increase plasma concentrations of both prolactin and renin. The serotonergic regulation of prolactin and renin secretion share several common characteristics. Serotonergic neurons originating in the dorsal raphe and terminating in the hypothalamus stimulate the secretion of both prolactin and renin. Destruction of cells in the hypothalamic paraventricular nucleus (PVN) inhibits both the prolactin and renin responses to 5-HT agonists and 5-HT-releasing drugs. Activation of 5-HT2 receptors increases the secretion of both prolactin and renin, while activation of other 5-HT receptor subtypes has differential effects on these hormones. However, there are also differences between the serotonergic mechanisms that regulate the secretion of prolactin and renin. Activation of 5-HT1A receptors increases the secretion of prolactin but not of renin. In addition, activation of peripheral 5-HT2 receptors stimulates the secretion of renin, while activation of peripheral 5-HT3 receptors increases plasma levels of prolactin but not renin. In humans, the effect of 5-HT-releasing drugs and 5-HT agonists on plasma prolactin concentrations has been studied to a greater extent than effects on most other hormones. In contrast, the renin response to 5-HT agonists and 5-HT releasers has not been well characterized in humans. Because of the important role of the renin-angiotensin system in cardiovascular regulation, studies on the serotonergic regulation of renin release in humans could increase our understanding of cardiovascular disorders associated with altered serotonergic function. Examples include anxiety and consequences of cocaine abuse. In conclusion, comparing the serotonergic regulation of prolactin and renin secretion indicates similarities that might shed light on common brain mechanisms that regulate neuroendocrine function.
 ...
PMID:Serotonergic regulation of renin and prolactin secretion. 878 3

The non-selective beta-blocker bopindolol, which was developed as a pro-drug, possessed 50-60 times more potent long-acting hypotensive effects on the blood pressure than those of atenolol or propranolol. Because this drug has only a mild partial agonist activity, it did not cause the rapid decrease in heart rate observed with atenolol or propranolol or the increase in heart rate induced by pindolol. These hypotensive effects are due to beta 1-antagonistic effects, not effects on beta 2- or beta 3-adrenoceptors. In addition to these effects, benefits of this drug include the following: slow dissociation rate from beta-adrenoceptors in tissues, high affinity to 5-HT1A subtypes, less clinical effects on lipid metabolism and the inhibition of renin release. It is possible that this drug possesses different pharmacological characteristics from other beta-blockers.
 ...
PMID:[Pharmacological characteristics of the long-acting beta-blocker "bopindolol"]. 906 94

Previous studies suggest that the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) increases the secretion of oxytocin, adrenocorticotropic hormone (ACTH), corticosterone and prolactin but not renin. However, the lack of selective 5-HT1A receptor antagonists made it difficult to confirm that 5-HT1A receptors mediate the neuroendocrine responses to 8-OH-DPAT. This study investigated the effects of increasing doses of a selective 5-HT1A receptor antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide (WAY-100635) on neuroendocrine responses induced by the 5-HT1A receptor agonist 8-OH-DPAT in adult male rats. 8-OH-DPAT, 500 microg/kg s.c., increased plasma levels of oxytocin (to 970% above basal levels); ACTH (to 1622% above basal levels), corticosterone (to 458% above basal levels) and prolactin (to 313% above basal levels), but not renin. The lowest dose of WAY-100635 (0.1 mg/kg s.c.) significantly inhibited the 8-OH-DPAT-induced increase in plasma oxytocin but not ACTH or corticosterone levels. At a dose of 1 mg/kg (s.c.), WAY-100635 completely blocked the oxytocin and ACTH responses and maximally inhibited the corticosterone response to 8-OH-DPAT, although corticosterone levels were still above basal. In contrast, the increase in prolactin secretion, induced by 8-OH-DPAT was not inhibited by any dose of WAY-100635. At the highest dose of WAY-100635 (10 mg/kg, s.c.), basal prolactin levels were markedly elevated (1550%) and administration of 8-OH-DPAT significantly elevated plasma renin concentration. Taken together, these data indicate that: (1) 8-OH-DPAT stimulates oxytocin, ACTH, and corticosterone but not prolactin secretion via activation of 5-HT1A receptors and (2) blockade of 5-HT1A receptors may unmask 8-OH-DPAT simulation of renin secretion via non-5-HT1A receptor mechanisms.
 ...
PMID:WAY-100635 inhibits 8-OH-DPAT-stimulated oxytocin, ACTH and corticosterone, but not prolactin secretion. 965 68


<< Previous 1 2 3 Next >>