Median eminence dopamine and serotonin neuronal activity. Temporal relationship to preovulatory prolactin and luteinizing hormone surges.
Using a high-performance liquid chromatography (HPLC) system coupled with an electrochemical detector, the concentrations of dopamine (DA) and 5-hydroxytryptamine (5-HT) and their major specific metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindole-3-acetic acid (5-HIAA), respectively, were measured in the median eminence (ME) throughout the rat estrous cycle. The ME DA content remained fairly constant throughout the estrous cycle except on estrus when 17.00 h values were significantly lower than 10.00 h values (40% decrease, p less than 0.05). The ME 5-HT content determined at 10.00 h was higher on proestrus than on any other day of the cycle. The ME DOPAC concentrations did not differ between 10.00 and 17.00 h on diestrus I, diestrus II or estrus. On the contrary, there was an almost linear decline between 10.00 and 17.00 h on proestrus (36% decrease, p less than 0.05). The ME 5-HIAA content did not differ between 10.00 and 17.00 h on any day of the estrous cycle. Significant changes were recorded for the DOPAC/DA and 5-HIAA/5-HT ratio in the ME on proestrus. There was a progressive decrease, starting from 10.00 h in the DOPAC/DA ratio with minimal values (42% decrease, p less than 0.05) at 16.00 h followed by an increase from 16.00 to 19.00 h. On the other hand, the 5-HIAA/5-HT ratio increased between 10.00 and 17.00 h (97% increase, p less than 0.05) and subsequently declined until 19.00 h (67% decrease vs. 17.00 h, p less than 0.05).2+hese data show that a concomitant
Kerdelhué
B
B
Unité de Neurobiologie de la Reproduction, CNRS-INRA, Jouy-en-Josas, France.
Bojda
F
F
Lesieur
P
P
Pasqualini
C
C
el Abed
A
A
Lenoir
V
V
Douillet
P
P
Chiueh
M C
MC
Palkovits
M
M
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000818:Animals; D004298:Dopamine / Q000032:analysis*; D004971:Estrus; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008473:Median Eminence / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis*
D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D011388:Prolactin; D007986:Luteinizing Hormone; D004298:Dopamine