ABSTRACT
Aim To investigate the selective inhibition of ethanol on muscarinic receptor-or 5-HT receptor-me-diated contractile responses in the circular smooth mus-cle strips isolated from the different regions of rat stom-ach. Methods Circular muscle strips isolated from the rat gastric fundus, body, cardia and pylorus were prepared, and the contractile responses to carbachol ( CCh ) or 5-HT were recorded. Results Ethanol (0. 000 05~0. 000 5, V/V) did not affect the contrac-tile response to CCh in circular muscle strips from the rat gastric fundus and cardia, and that to 5-HT in the strips from rat gastric fundus and body ( P >0. 05 ) . However, ethanol(0. 000 1 and 0. 000 5) significantly inhibited the Emax value of the contraction by CCh from (12. 18 ± 0. 33) g of control level to (10. 88 ± 0. 41) g and -lgEC50 value from ( 6. 33 ± 0. 05 ) of control level to (6. 12 ± 0. 06)(P <0. 05) in the strips from rat gastric body. Ethanol(0. 000 1 and 0. 000 5) also significantly inhibited the Emax value of the contraction by CCh from (2. 87 ± 0. 15) g of control level to (2. 2 ± 0. 13) g and -lgEC50 value from (6. 49 ± 0. 10) of control level to (6. 05 ± 0. 09)(P<0. 01) in the strips from rat gastric pylorus. Moreover, ethanol ( 0. 000 1 and 0. 000 5) significantly inhibited the Emax value of the contraction by 5-HT from (2. 93 ± 0. 35) g of con-trol level to ( 2. 1 ± 0. 30 ) g ( P<0. 05 ) , but did not affect the -lgEC50 value in the strips from rat gastric cardia. Conclusions Ethanol inhibits the contractile responses to 5-HT only in the circular muscle strips of rat gastric cardia, and it inhibits the contractile respon-ses to CCh more strongly in the circular muscle strips of gastric pylorus than gastric body. In those gastric circular muscle strips, ethanol decreases both the ac-tivity and affinity of CCh to muscarinic receptors, but decreases only the activity of 5-HT to its receptors.
ABSTRACT
The use of thyroid hormones as an effective adjunct treatment for affective disorders has been studied over the past three decades and has been conformed repeatedly. Interaction of the thyroid and monoamine neurotransmitter systems has been suggested as a potential underline mechanism of action. While catecholamine and thyroid interrelationships have been reviewed in detail, the serotonin system has been relatively neglected. Thus, the goal of this article is to review the literature on the relationship between thyroid hormones and the brain serotonin (5-HT) system. In humans, neuroendocrine challenge studies in hypothyroid patients have shown a reduced 5-HT responsiveness that is reversible with replacement therapy. In the majority of the studies, the effects of thyroid hormone administration in animals will experimentally-induced hypothyroid sates include an increase in cortical 5-HT concentrations and a desensitization of auto inhibitory 5-HT1A receptors in the rap he area, resulting in disinhibition of cortical hippocampal 5-HT release. Furthermore, there is some indication that thyroid hormones may increase cortical 5-HT2 receptor sensitivity. In conclusion, there is robust evidence, particularly from animal studies, that the thyroid economy has a modulating impact in the brain serotonin system. Thus it is postulated that one mechanism, among others, through which exogenous thyroid hormones may exert their modulatory effects in affective illness is via an increase in serotonergic neurotransmission, specifically by reducing the sensitivity of 5-HT1A auto receptors in the raphe area, and by increasing 5-HT2 receptor sensitivity.
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Nausea and emesis are a major side effect and obstacle for chemotherapy in cancer patients. Employ of antiemetic drugs help to suppress chemotherapy-induced emesis in some patients but not all patients. Ginger, an herbal medicine, has been traditionally used to treat various kinds of diseases including gastrointestinal symptoms. Ginger is effective in alleviating nausea and emesis, particularly, for cytotoxic chemotherapy drug-induced emesis. Ginger-mediated antiemetic effect has been attributed to its pungent constituents-mediated inhibition of serotonin (5-HT) receptor activity but its cellular mechanism of action is still unclear. Emetogenic chemotherapy drugs increase 5-HT concentration and activate visceral vagal afferent nerve activity. Thus, 5-HT mediated vagal afferent activation is essential to provoke emesis during chemotherapy. In this experiment, water extract of ginger and its three major pungent constituent's effect on 5-HT-evoked responses were tested on acutely dispersed visceral afferent neurons with patch-clamp methods. The ginger extract has similar effects to antiemetic drug ondansetron by blocking 5-HT-evoked responses. Pungent constituents of the ginger, [6]-shogaol, [6]-gingerol, and zingerone inhibited 5-HT responses in a dose dependent manner. The order of inhibitory potency for these compounds were [6]-shogaol>[6]-gingerol>zingerone. Unlike well-known competitive 5-HT3 receptor antagonist ondansetron, all tested ginger constituents acted as non-competitive antagonist. Our results imply that ginger and its pungent constituents exert antiemetic effects by blocking 5-HT-induced emetic signal transmission in vagal afferent neurons.
Subject(s)
Humans , Antiemetics , Drug Therapy , Ginger , Herbal Medicine , Nausea , Neurons , Neurons, Afferent , Ondansetron , Receptors, Serotonin, 5-HT3 , Serotonin , Visceral Afferents , Vomiting , WaterABSTRACT
0.05).Conclusion:The lymphoid tissues can not only express the ACTH-R?5-HT_ 1A-R protein but also synthesize their mRNA.ACTH and 5-HT can regulate the functions of the immune system through their receptors on the membrane of the immunocytes.
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Objective:To explore the 5-HT mechanism of stress . Methods:The method of polymerase chain reaction (PCR) was used to detect the presence of 5-HT receptor subtypes in the hippocampus,hypothalamic and midbrain of the rat after 30days of movement restrict compared with normal cage control groups (CC) . The specific oligonucleotide primers were synthesized based on the complementary DNA sequence for each of the rat 5-HT 1A and 5-HT 2A receptor subtypes . Results : The expression of 5-HT 1A receptor subtypes in each regions of the rat brain after movement restrict were signifcantly lower than that of the CC groups, and the expression of 5-HT 2A receptor subtype were signifcantly higher( P
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Studies using isolated rat fundus strip preparation demonstrated that l-stephanine ( l-STP ) , l-roemerine ( 1-REM ), l-stepholidine (l-SPD), 1-tetrahydropalmatine ( l-THP ) and dl-tetrahydrode-berine ( THB ) possessed 5-HT blockade properties. 1-STP ( 16, 25 ?M ) produced competitve antagonism against 5-HT receptor on rat fundus, while higher concentration ( 50 ?M ) suggested a non-competi tive inhibition, with pA2' and2' values equal to 5.8 and 4.2 respectively. 1-REM was found to be a non-competitive antagonIst ( pD' 2 = 4.5). 1-SPD, 1-THP and THB cuased a parallel shift to the right of 5-HT concentration response curve without any significant changes in their maximum response, indicating that they were competitive antagonists of 5-HT receptor. The antagonistic potencies of 1-SPD, l-THP and THB were expressed as pA2 values: 6.2,5.2 and 5.0.