Alterations in hypothalamic mechanisms associated with reduced suckling-induced PRL secretion in the lactation deficient OFA hr/hr rat

PENNACCHIO, GISELA E.; AYALA, CAROLINA; SANCHEZ, MARÍA BELÉN; MORENO-SOSA, MARÍA TAMARA; CAMPO-VERDE-ARBOCCÓ, FIORELLA; JAHN, GRACIELA ALMA; VALDEZ, SUSANA RUTH; SOAJE, MARTA

NEUROENDOCRINOLOGY

KARGER

Año: 2022

0028-3835

Introduction: OFA hr/hr rats havedeficient lactation with impaired suckling-induced PRL release. Unlike theirbackground strain, Sprague-Dawley (SD) rats, OFA rats display abnormalmediobasal hypothalamus (MBH) dopaminergic tone during late pregnant andlactation. We explored if the expression of MBH components, including variousreceptors (R) and proteins that regulate the dopaminergic system is altered inmid-lactating OFA compared to SD rats, which may be associated to theabnormality. Methods: Four groups of mid-lactating rats were used: continuouslactation; pups separated overnight; 30 min suckling (S); 2h or 4h S afterseparation. Mothers were sacrificed to obtain serum for PRL RIA and MBHs todetermine tyrosine hydroxylase (TH), PRL-R, PRL signaling molecules (activator:STAT5b; inhibitors: SOCS1, SOCS3, CIS), opioids (PENK, PDYN) and µ- and k-opioid R (MOR, KOR) mRNA expression by qPCR andphospho-TH (p-TH) and TH proteins by Western blot. Results: suckling-inducedPRL was lower in OFA and p-TH expression diminished in both strains. Separationincreased TH mRNA and protein in SD, which decreased after 4h S, but OFAprotein levels remained unchanged. Separation of pups also resulted in decreasedPRL-R and CIS expression in SD but increased PRL-R and SOCS3 in OFA. Despitethe lower PRL-R, STAT5b, SOCS1 and SOCS3 levels in OFA compared to SD, sucklingdiminished them further. We observed subtle changes in SD opioids and their R,but in OFA, suckling decreased PENK, KOR and MOR. Conclusion: the differentpatterns of TH, opioids, their R, and PRL signaling inhibitors expression withconserved TH activation by suckling may disturb the balance between stimulationand inhibition of PRL release resulting in impaired suckling-induced PRLsecretion in OFA rats. @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;}