MILD HYPERTHYROIDISM AFFECTS PROLACTIN SECRETION INDUCED BY ACUTE STRESS IN LACTATING RATS

NEIRA, FLAVIA JUDITH; SÁNCHEZ MARÍA BELÉN; MICHEL, MARÍA CECILIA; TRONCOSO MARIANA; PIETROBON, ELISA OLIVIA; SOAJE, MARTA; MACKERN-OBERTI, JUAN PABLO; JAHN, GRACIELA A; VALDEZ, SUSANA R

SAN LUIS

Congreso; Sociedad de Biología de Cuyo; 2021

Sociedad de Biología de Cuyo

Hyperthyroidism (HyperT) has higherincidence in women than in men and can cause reproductive disorders affectinglactation. Pregnancy and lactation are regulated by intricate centralneuroendocrine mechanisms present in areas such as the medial basal hypothalamus(MBH), wich includes the main dopaminergic neuronal group that regulatesProlactin (PRL) secretion. PRL has various functions at the central level andits receptor is expressed in different brain regions that modulate the responseto stress. We evaluated the effect of mild HyperT on PRL release in response toacute stress in lactating rats. HyperT was induced with T4 (0.1mg /kg/day,s.c.) a dose that allows the maintenance of lactation. Control (Con) and HyperTfemale Wistar rats were bled from the tail vein during the 2 min ether exposure(s1) and 5 min after ether exposure (s2). We analyzed serum PRL levels on day19 of gestation (G19), day 2 (L2) and 12 (L12) of lactation.  To explore the neuroendocrine mechanisms ofPRL release during lactation, we also determined by RT-qPCR the expression ofthyroid receptor (TR), the long isoform of the prolactin receptor (PRLLR)members of the PRL signaling pathway (STAT5b; CIS; SOCS), progesterone receptor(PR), estrogen receptor (ER) and glucocorticoid receptor (GR) in MBH of rats onG19, L2 and L12 of lactation in non-stressed Con and HyperT groups. On G19acute stress induced PRL release in HyperT (p<0.05), while no response wasobserved in Con rats. On L2 no response to stress was observed in both Con and HiperTrats, but basal, s1 and s2 PRL levels were lower in HyperT compared to Con rats(p<0.05, p<0.05 and p<0.01, respectively). On L12 HyperT decreased PRLsecretion and stress increased PRL levels in Con rats (p<0.05). In MBH, TRβ1expression was higher on L12 compared to L2 and G19 in the HyperT (p<0.001)and TRβ1 expression was increased in HyperT compared to Con on L12. TRβ2expression decreased on HyperT with respect to Con on L12 (p<0.05). STAT5bexpression increased on L12 in both HyperT and Con groups compared with L2 andG19. CIS expression decreased on L2 in HyperT compared to Con group(p<0.05). These results indicate that HyperT reduces PRL secretion inresponse to acute stress during lactation that could be regulated by changes inthe expression on TR and PRL effectors, CIS and STAT5b in MBH.@font-face{font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1107305727 0 0 415 0;}@font-face{font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1073786111 1 0 415 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin:0cm;margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:12.0pt;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-TRAD;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-TRAD;}div.WordSection1{page:WordSection1;}@font-face{font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1107305727 0 0 415 0;}@font-face{font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1073786111 1 0 415 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin-top:0cm;margin-right:0cm;margin-bottom:8.0pt;margin-left:0cm;line-height:107%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-AR;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-TRAD;}div.WordSection1{page:WordSection1;}