Changes in and dorsal to the rat suprachiasmatic nucleus during early pregnancy.
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.
Schrader
J A
JA
Department of Zoology, Michigan State University, East Lansing, MI 48824, USA.
Nunez
A A
AA
Smale
L
L
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*
D016761:Oncogene Proteins v-fos; C513311:Per2 protein, rat; D056950:Period Circadian Proteins
Am J Physiol. 1996 Oct;271(4 Pt 2):R1063-9
8898001
Brain Res. 2004 Jun 4;1010(1-2):35-44
15126115
Mol Cell Endocrinol. 2006 Jun 27;252(1-2):46-56
16793198
Nat Rev Neurosci. 2003 Aug;4(8):649-61
12894240
Physiol Rev. 2000 Oct;80(4):1523-631
11015620
Physiol Behav. 1988;42(5):477-84
3393610
Endocrinology. 1995 Feb;136(2):512-20
7835284
J Comp Neurol. 1992 Nov 22;325(4):559-71
1361497
J Neuroendocrinol. 2008 Jun;20(6):665-72
18601687
Brain Res. 2000 Jul 7;870(1-2):54-65
10869501
J Comp Neurol. 1998 Feb 16;391(3):397-405
9492207
Endocrinology. 2006 Mar;147(3):1148-53
16373412
Chronobiol Int. 2009 Oct;26(7):1290-306
19916832
Proc Natl Acad Sci U S A. 1972 Jun;69(6):1583-6
4556464
Proc Natl Acad Sci U S A. 2006 Apr 4;103(14):5591-6
16554373
Neuroscience. 2004;127(1):13-23
15219664
Science. 1990 Jun 8;248(4960):1237-40
2112267
Physiol Behav. 1973 Feb;10(2):225-9
4736131
J Endocrinol. 1979 Nov;83(2):267-74
521741
Endocrinology. 1972 Apr;90(4):1125-7
5011056
Am J Physiol. 1989 Nov;257(5 Pt 2):R1241-50
2589549
Neuroendocrinology. 1998 Feb;67(2):83-93
9508038
Neuroscience. 2008 Sep 22;156(1):48-58
18692118
Neuroscience. 1994 Feb;58(3):573-83
8170538
Brain Res. 1988 Oct 18;462(2):301-12
3191391
J Biol Rhythms. 1999 Aug;14(4):275-80
10447307
Neuroreport. 1993 Feb;4(2):128-30
8453048
Am J Physiol Regul Integr Comp Physiol. 2000 Dec;279(6):R2270-6
11080095
Nat Rev Genet. 2005 Jul;6(7):544-56
15951747
Eur J Neurosci. 2007 Jun;25(11):3195-216
17552989
Am J Physiol Regul Integr Comp Physiol. 2000 Dec;279(6):R2262-9
11080094
J Comp Neurol. 1972 Sep;146(1):1-14
4116104
Trends Neurosci. 2005 Mar;28(3):145-51
15749168
Chronobiol Int. 2005;22(2):179-205
16021838
Brain Res. 1972 Jul 13;42(1):201-6
5047187
J Comp Neurol. 2001 May 7;433(3):312-34
11298358
Nature. 2002 Aug 29;418(6901):935-41
12198538
Brain Res. 2005 Jun 28;1048(1-2):161-9
15913573
Cell. 1999 Jan 22;96(2):271-90
9988221
Chronobiol Int. 1987;4(2):183-7
3508739
J Comp Neurol. 1987 Apr 8;258(2):204-29
3294923
J Neurosci. 2001 Jul 1;21(13):4864-74
11425913
Brain Res. 2002 Dec 27;958(2):261-71
12470861
Neuroscience. 1994 Jul;61(2):391-410
7526267
Physiol Behav. 1985 Jan;34(1):61-3
4041051
Proc Soc Exp Biol Med. 1949 Oct;72(1):78-80
15391680
J Biol Rhythms. 2007 Feb;22(1):3-13
17229920
Am J Physiol. 1999 Nov;277(5):R1493-500
10564224
J Comp Neurol. 1987 Apr 8;258(2):230-52
2438309
Neuroscience. 2004;124(3):695-707
14980739
Cell Tissue Res. 2002 Jul;309(1):89-98
12111539
Science. 1990 Feb 23;247(4945):975-8
2305266
Physiol Behav. 1981 Jan;26(1):21-5
7195042
J Comp Neurol. 1991 Apr 8;306(2):344-60
1711060
Neuroscience. 2000;98(3):535-47
10869847
J Comp Neurol. 2004 Jan 12;468(3):361-79
14681931
Neurosci Lett. 1993 Feb 5;150(1):112-6
8097023
Trends Neurosci. 2005 Mar;28(3):152-7
15749169
Am J Physiol. 1981 Jul;241(1):R62-6
7246802
Horm Behav. 2005 Jan;47(1):8-13
15579260
Biol Reprod. 1980 Aug;23(1):64-71
7191337