Acute effect of manganese on hypothalamic luteinizing hormone releasing hormone secretion in adult male rats: involvement of specific neurotransmitter systems.
Manganese chloride (MnCl2) is capable of stimulating luteinizing hormone releasing hormone (LHRH) secretion in adult male Sprague-Dawley rats through the activation of the hypothalamic nitric oxide/cyclic guanosine monophosphate (cGMP)/protein kinase G pathway. The present study aimed to determine the involvement of specific neurotransmitters involved in this action. Our results indicate that dopamine, but not glutamic acid and prostaglandins, mediates the MnCl2 stimulated secretion of LHRH from medial basal hypothalami in vitro, as well as increases the activity of nitric oxide synthase. Furthermore, a biphasic response was observed in that gamma aminobutyric acid (GABA) release was also increased, which acts to attenuate the MnCl2 action to stimulate LHRH secretion. Although it is clear that manganese (Mn+2) can acutely induce LHRH secretion in adult males, we suggest that the additional action of MnCl2 to release GABA, a LHRH inhibitor, may ultimately contribute to suppressed reproductive function observed in adult animals following exposure to high chromic levels of Mn+2.
Prestifilippo
Juan Pablo
JP
Center of Pharmacological and Botanical Studies (CEFyBO-CONICET-UBA), Facultad de Medicina, UBA, Paraguay 2155, Piso 16, Buenos Aires, Argentina. jprestifilippo@yahoo.com.ar
Fernández-Solari
Javier
J
De Laurentiis
Andrea
A
Mohn
Claudia Ester
CE
de la Cal
Carolina
C
Reynoso
Roxana
R
Dees
W Les
WL
Rettori
Valeria
V
D000367:Age Factors; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D002712:Chlorides / Q000633:toxicity*; D004298:Dopamine / Q000378:metabolism*; D052244:Endocrine Disruptors / Q000633:toxicity*; D018698:Glutamic Acid / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000097:blood / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D017895:Manganese Compounds; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011388:Prolactin / Q000097:blood; D011453:Prostaglandins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D002712:Chlorides; D052244:Endocrine Disruptors; D017895:Manganese Compounds; D011453:Prostaglandins; D009569:Nitric Oxide; D007987:Gonadotropin-Releasing Hormone; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D011388:Prolactin; D019001:Nitric Oxide Synthase; D002122:Calcium Chloride; C025340:manganese chloride; D004298:Dopamine