Fos immunoreactivity in the suprachiasmatic nuclei of golden hamsters bearing an ectopic pituitary graft.
Young male golden hamsters, made hyperprolactinemic by a pituitary graft under the kidney capsule, were exposed to a light pulse (1,000 lx/30 min) at Zeitgeber time (ZT) 18. Controls included hamsters receiving a sham graft (muscle). Fos immunoreactive cells were counted in both suprachiasmatic nuclei (SCN) of each animal, using an image analyzer system. The Fos immunoreactivity (Fos-ir) of the ventrolateral and dorsomedial SCN regions was greater in the pituitary-grafted hamsters. Indeed, light induced the greatest response in grafted animals in both SCN regions. However, the SCN of pituitary-grafted hamsters in the absence of light showed the lowest Fos-ir in both regions. The results support the occurrence of a dual effect of hyperprolactinemia on Fos-ir in the SCN of hamsters at ZT 18, with inhibition of Fos expression in the absence of light and potentiation of early gene expression when animals were exposed to a light pulse.
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina. rcutera@fmed.uba.ar
R A
RA
Cutrera
V I
VI
Boggio
P O
PO
Castrillón
P A
PA
Scacchi
A I
AI
Esquifino
D P
DP
Cardinali
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D006224:Cricetinae; D005260:Female; D005786:Gene Expression Regulation / Q000528:radiation effects; D016762:Genes, fos; D006729:Hormones, Ectopic / Q000378:metabolism / Q000502:physiology*; D006966:Hyperprolactinemia / Q000209:etiology / Q000503:physiopathology*; D007124:Immunoenzyme Techniques; D007668:Kidney; D008027:Light; D008297:Male; D008647:Mesocricetus; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000096:biosynthesis; D010902:Pituitary Gland / Q000378:metabolism* / Q000637:transplantation; D011388:Prolactin / Q000378:metabolism / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis* / Q000096:biosynthesis; D011981:Receptors, Prolactin / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D016042:Transplantation, Heterotopic; D014184:Transplantation, Homologous
D006729:Hormones, Ectopic; D009419:Nerve Tissue Proteins; D016760:Proto-Oncogene Proteins c-fos; D011981:Receptors, Prolactin; D011388:Prolactin