Postnatal function of the somatotrophic axis in pigs born naturally or by Caesarian section.
This study was designed to determine what effects the birth process would have on development of the somatotrophic axis in neonatal pigs. Eight crossbred sows were selected (n = 4 natural birth and n = 4 Caesarian section) for the present study. Blood and tissue samples from 38 pigs were collected at birth. Twenty pigs were maintained with natural birth sows until sacrificed for blood and tissue collection at 2 wk of age. Gestational age at birth did not differ (P > 0.16) between natural birth and C-section pigs. Average daily gain (ADG) from birth until 2 wk of age was reduced (P < 0.0001) by 39.3% in the C-section pigs as compared to the natural birth pigs. Serum growth hormone (GH) did not differ (P > 0.86) at birth, but was greater (P < 0.024) at 2 wk in C-section pigs. Serum insulin-like growth factor 1 (IGF-1) was greater at birth (P < 0. 0025) and at 2 wk of age (P < 0.035) in the natural birth pigs. Serum concentration of IGF-2 did not differ at birth (P > 0.8) but was greater (P < 0.043) in natural birth pigs at 2 wk of age. Pituitary content of GH mRNA and GH-releasing hormone receptor mRNA did not differ (P > 0.90) between groups regardless of age; however, expression of both mRNAs declined (P < 0.0003) from birth until 2 wk of age. There tended to be a birth type X age interaction (P < 0. 082) for liver IGF-1 mRNA such that C-section pigs had a greater expression at 2 wk of age. Liver IGF-1 mRNA expression increased (P < 0.0001) in both groups from birth to 2 wk of age. Liver expression of GH receptor mRNA was greater in C-section pigs at birth (P < 0. 04) and 2 wk of age (P < 0.03). These data provide evidence that the natural birth process affects postnatal development and/or function of the somatotrophic axis in the neonatal pig.
Carroll
J A
JA
Animal Physiology Research Unit, Agricultural Research Service, United States Department of Agriculture, Animal Sciences Research Center, University of Missouri, Columbia, Missouri 65211, USA. CarrollJA@Missouri.edu
Daniel
J A
JA
Keisler
D H
DH
Matteri
R L
RL
D000375:Aging; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000502:physiology*; D001724:Birth Weight; D002585:Cesarean Section / Q000662:veterinary*; D036861:Delivery, Obstetric / Q000662:veterinary*; D005260:Female; D015870:Gene Expression; D005865:Gestational Age; D013006:Growth Hormone / Q000097:blood / Q000235:genetics / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D008099:Liver / Q000737:chemistry; D010902:Pituitary Gland / Q000737:chemistry / Q000502:physiology*; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D018013:Receptors, Neuropeptide / Q000235:genetics; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics; D013552:Swine / Q000502:physiology*; D015430:Weight Gain
D012333:RNA, Messenger; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; C048250:somatotropin releasing hormone receptor