title: 5-HT1 and 5-HT2 receptor activation reduces N-methyl-D-aspartate (NMDA)-stimulated LH secretion in prepubertal male and female rats.
abstract: OBJECTIVE
  Excitatory amino acids and serotonin are involved in the control of gonadotropin secretion. The actions of these neurotransmitters are interconnected and recently we have reported that 5-HT(1) and 5-HT(2) receptor agonists blunted (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-stimulated GH secretion in prepubertal rats. The present experiments were carried out to analyze the effects of activation of different 5-hydroxytryptamine (5-HT) receptor subtypes on gonadotropin secretion and their role in the N-methyl-d-aspartate (NMDA)-stimulated LH release.
  
  
  METHODS
  We analyzed the gonadotropin secretion after manipulation of serotoninergic and aminoacidergic systems and their interactions in 5-, 16- and 23-day-old male and female rats. To this end, serum LH and FSH concentrations were measured in rats treated with 5-hydroxytryptophan methyl ester (5-HTP) (a precursor of 5-HT synthesis) plus Fluoxetine (Fx, a blocker of 5-HT reuptake), d,l-p-chlorophenyl-alanine methyl ester (PCPA, a blocker of 5-HT synthesis), R-(+)-8-hydroxydipropylaminotetralin hydrobromide (8-OH-DPAT, an agonist of 5-HT(1A) receptors), (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) and alpha-methyl-5-hydroxytryptamine (alpha-Me-5-HT, agonists of 5-HT(2) receptors), and 1-Phenylbiguanide (1-PHE an agonist of 5-HT(3) receptors). In addition, the effects of 8-OH-DPAT and DOI on NMDA-stimulated LH secretion were analyzed.
  
  
  RESULTS
  Neither the activation nor blockade of the serotoninergic system modified LH secretion. Basal gonadotropin secretion remained unchanged in 23-day-old male and female rats after activation of 5-HT(1A), 5-HT(2) and 5-HT(3) receptors. The stimulatory effect of NMDA on LH secretion was blocked in both sexes after activation of the serotoninergic system, through specific 5-HT(1) and 5-HT(2) receptor agonists.
  
  
  CONCLUSIONS
  Activation of serotoninergic receptors decreased the stimulatory effect of NMDA on LH secretion in prepubertal male and female rats.
authors.affiliation: Department of Physiology, Faculty of Medicine, Cordoba University, Avda Menendez Pidal s/n, Cordoba 14004, Spain.
authors.forename: Leonor
authors.initials: L
authors.lastname: Pinilla
authors.forename: Lucas C
authors.initials: LC
authors.lastname: Gonzalez
authors.forename: Manuel
authors.initials: M
authors.lastname: Tena-Sempere
authors.forename: Enrique
authors.initials: E
authors.lastname: Aguilar
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D001645:Biguanides / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D005260:Female; D010134:Fenclonine / Q000031:analogs & derivatives* / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin / Q000031:analogs & derivatives* / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D012741:Sexual Maturation; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
chemical_list: D000662:Amphetamines; D001645:Biguanides; D018690:Excitatory Amino Acid Agonists; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C042390:alpha-methylserotonin; C020261:4-chlorophenylalanine methyl ester; D012701:Serotonin; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D007986:Luteinizing Hormone; D006916:5-Hydroxytryptophan; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine; D010134:Fenclonine; C008846:phenyl biguanide