title: Changes in and dorsal to the rat suprachiasmatic nucleus during early pregnancy.
abstract: Circadian rhythms in behavior and physiology change as female mammals transition from one reproductive state to another. The mechanisms responsible for this plasticity are poorly understood. The suprachiasmatic nucleus (SCN) of the hypothalamus contains the primary circadian pacemaker in mammals, and a large portion of its efferent projections terminate in the ventral subparaventricular zone (vSPZ), which also plays important roles in rhythm regulation. To determine whether these regions might mediate changes in overt rhythms during early pregnancy, we first compared rhythms in Fos and Per2 protein expression in the SCN and vSPZ of diestrous and early pregnant rats maintained in a 12:12-h light/dark (LD) cycle. No differences in the Fos rhythm were seen in the SCN core, but in the SCN shell, elevated Fos expression was maintained throughout the light phase in pregnant, but not diestrous, rats. In the vSPZ, the Fos rhythm was bimodal in diestrous rats, but this rhythm was lost in pregnant rats. Peak Per2 expression was phase-advanced by 4 h in the SCN of pregnant rats, and some differences in Per2 expression were found in the vSPZ as well. To determine whether differences in Fos expression were due to altered responsivity to light, we next characterized light-induced Fos expression in the SCN and vSPZ of pregnant and diestrous rats in the mid-subjective day and night. We found that the SCN core of the two groups responded in the same way at each time of day, whereas the rhythm of Fos responsivity in the SCN shell and vSPZ differed between diestrous and pregnant rats. These results indicate that the SCN and vSPZ are functionally re-organized during early pregnancy, particularly in how they respond to the photic environment. These changes may contribute to changes in overt behavioral and physiological rhythms that occur at this time.
authors.affiliation: Department of Zoology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Schrader
authors.forename: A A
authors.initials: AA
authors.lastname: Nunez
authors.forename: L
authors.initials: L
authors.lastname: Smale
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D003624:Darkness; D004031:Diestrus / Q000378:metabolism; D005260:Female; D008027:Light; D008297:Male; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D056950:Period Circadian Proteins / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*
chemical_list: D016761:Oncogene Proteins v-fos; C513311:Per2 protein, rat; D056950:Period Circadian Proteins
references.citation: Am J Physiol. 1996 Oct;271(4 Pt 2):R1063-9
references.pmid: 8898001
references.citation: Brain Res. 2004 Jun 4;1010(1-2):35-44
references.pmid: 15126115
references.citation: Mol Cell Endocrinol. 2006 Jun 27;252(1-2):46-56
references.pmid: 16793198
references.citation: Nat Rev Neurosci. 2003 Aug;4(8):649-61
references.pmid: 12894240
references.citation: Physiol Rev. 2000 Oct;80(4):1523-631
references.pmid: 11015620
references.citation: Physiol Behav. 1988;42(5):477-84
references.pmid: 3393610
references.citation: Endocrinology. 1995 Feb;136(2):512-20
references.pmid: 7835284
references.citation: J Comp Neurol. 1992 Nov 22;325(4):559-71
references.pmid: 1361497
references.citation: J Neuroendocrinol. 2008 Jun;20(6):665-72
references.pmid: 18601687
references.citation: Brain Res. 2000 Jul 7;870(1-2):54-65
references.pmid: 10869501
references.citation: J Comp Neurol. 1998 Feb 16;391(3):397-405
references.pmid: 9492207
references.citation: Endocrinology. 2006 Mar;147(3):1148-53
references.pmid: 16373412
references.citation: Chronobiol Int. 2009 Oct;26(7):1290-306
references.pmid: 19916832
references.citation: Proc Natl Acad Sci U S A. 1972 Jun;69(6):1583-6
references.pmid: 4556464
references.citation: Proc Natl Acad Sci U S A. 2006 Apr 4;103(14):5591-6
references.pmid: 16554373
references.citation: Neuroscience. 2004;127(1):13-23
references.pmid: 15219664
references.citation: Science. 1990 Jun 8;248(4960):1237-40
references.pmid: 2112267
references.citation: Physiol Behav. 1973 Feb;10(2):225-9
references.pmid: 4736131
references.citation: J Endocrinol. 1979 Nov;83(2):267-74
references.pmid: 521741
references.citation: Endocrinology. 1972 Apr;90(4):1125-7
references.pmid: 5011056
references.citation: Am J Physiol. 1989 Nov;257(5 Pt 2):R1241-50
references.pmid: 2589549
references.citation: Neuroendocrinology. 1998 Feb;67(2):83-93
references.pmid: 9508038
references.citation: Neuroscience. 2008 Sep 22;156(1):48-58
references.pmid: 18692118
references.citation: Neuroscience. 1994 Feb;58(3):573-83
references.pmid: 8170538
references.citation: Brain Res. 1988 Oct 18;462(2):301-12
references.pmid: 3191391
references.citation: J Biol Rhythms. 1999 Aug;14(4):275-80
references.pmid: 10447307
references.citation: Neuroreport. 1993 Feb;4(2):128-30
references.pmid: 8453048
references.citation: Am J Physiol Regul Integr Comp Physiol. 2000 Dec;279(6):R2270-6
references.pmid: 11080095
references.citation: Nat Rev Genet. 2005 Jul;6(7):544-56
references.pmid: 15951747
references.citation: Eur J Neurosci. 2007 Jun;25(11):3195-216
references.pmid: 17552989
references.citation: Am J Physiol Regul Integr Comp Physiol. 2000 Dec;279(6):R2262-9
references.pmid: 11080094
references.citation: J Comp Neurol. 1972 Sep;146(1):1-14
references.pmid: 4116104
references.citation: Trends Neurosci. 2005 Mar;28(3):145-51
references.pmid: 15749168
references.citation: Chronobiol Int. 2005;22(2):179-205
references.pmid: 16021838
references.citation: Brain Res. 1972 Jul 13;42(1):201-6
references.pmid: 5047187
references.citation: J Comp Neurol. 2001 May 7;433(3):312-34
references.pmid: 11298358
references.citation: Nature. 2002 Aug 29;418(6901):935-41
references.pmid: 12198538
references.citation: Brain Res. 2005 Jun 28;1048(1-2):161-9
references.pmid: 15913573
references.citation: Cell. 1999 Jan 22;96(2):271-90
references.pmid: 9988221
references.citation: Chronobiol Int. 1987;4(2):183-7
references.pmid: 3508739
references.citation: J Comp Neurol. 1987 Apr 8;258(2):204-29
references.pmid: 3294923
references.citation: J Neurosci. 2001 Jul 1;21(13):4864-74
references.pmid: 11425913
references.citation: Brain Res. 2002 Dec 27;958(2):261-71
references.pmid: 12470861
references.citation: Neuroscience. 1994 Jul;61(2):391-410
references.pmid: 7526267
references.citation: Physiol Behav. 1985 Jan;34(1):61-3
references.pmid: 4041051
references.citation: Proc Soc Exp Biol Med. 1949 Oct;72(1):78-80
references.pmid: 15391680
references.citation: J Biol Rhythms. 2007 Feb;22(1):3-13
references.pmid: 17229920
references.citation: Am J Physiol. 1999 Nov;277(5):R1493-500
references.pmid: 10564224
references.citation: J Comp Neurol. 1987 Apr 8;258(2):230-52
references.pmid: 2438309
references.citation: Neuroscience. 2004;124(3):695-707
references.pmid: 14980739
references.citation: Cell Tissue Res. 2002 Jul;309(1):89-98
references.pmid: 12111539
references.citation: Science. 1990 Feb 23;247(4945):975-8
references.pmid: 2305266
references.citation: Physiol Behav. 1981 Jan;26(1):21-5
references.pmid: 7195042
references.citation: J Comp Neurol. 1991 Apr 8;306(2):344-60
references.pmid: 1711060
references.citation: Neuroscience. 2000;98(3):535-47
references.pmid: 10869847
references.citation: J Comp Neurol. 2004 Jan 12;468(3):361-79
references.pmid: 14681931
references.citation: Neurosci Lett. 1993 Feb 5;150(1):112-6
references.pmid: 8097023
references.citation: Trends Neurosci. 2005 Mar;28(3):152-7
references.pmid: 15749169
references.citation: Am J Physiol. 1981 Jul;241(1):R62-6
references.pmid: 7246802
references.citation: Horm Behav. 2005 Jan;47(1):8-13
references.pmid: 15579260
references.citation: Biol Reprod. 1980 Aug;23(1):64-71
references.pmid: 7191337