TY - JOUR
T1 - Mammary somatosensory pathways are not required for suckling-mediated inhibition of luteinizing hormone secretion and delay of ovulation in cows
AU - Williams, G. L.
AU - McVey, W. R.
AU - Hunter, J. F.
PY - 1993
Y1 - 1993
N2 - Four experiments were conducted to evaluate endocrine, lactational, and reproductive features of an experimental animal model employing complete neural disconnection of the udder in beef cows and then to utilize the validated model to study the role of mammary somatosensory pathways in suckling-mediated anovulation. For experiment 1, crossbred beef cows (n = 16) were randomly assigned to suckled/sham-operated control, weaned (calf removed)/sham-operated control, and suckled/mammary-denervated groups between Days 14 and 18 postcalving. Ten additional cows were randomly divided into weaned or suckled unoperated control groups (experiment 2). Complete mammary anesthesia was attained in all denervated cows (experiment 1), but sensory perception was not affected in sham-operated controls. Prolactin release patterns were markedly depressed by denervation; however, oxytocin release, milk production, and calf growth rates were not affected. Although acute sham surgery attenuated weaning-induced increases in LH pulse and ovulation frequency (experiment 1), normal responses to weaning were observed in unoperated controls (experiment 2) as well as in sham-operated cows 1 yr later (experiment 3). Finally, denervated-suckled cows (n = 22) that had been denervated before conception (experiment 4) exhibited LH secretion patterns and mean postpartum intervals to luteal activity similar to those of intact- suckled cows (n = 16). In contrast, the intact-weaned group (n = 16; calves weaned at birth) responded within 2 wk postcalving with an increased frequency of LH pulses, and intervals to onset of luteal activity were shortened compared to those in the other groups. Suckling-mediated anovulation is not dependent upon mammary somatosensory cues.
AB - Four experiments were conducted to evaluate endocrine, lactational, and reproductive features of an experimental animal model employing complete neural disconnection of the udder in beef cows and then to utilize the validated model to study the role of mammary somatosensory pathways in suckling-mediated anovulation. For experiment 1, crossbred beef cows (n = 16) were randomly assigned to suckled/sham-operated control, weaned (calf removed)/sham-operated control, and suckled/mammary-denervated groups between Days 14 and 18 postcalving. Ten additional cows were randomly divided into weaned or suckled unoperated control groups (experiment 2). Complete mammary anesthesia was attained in all denervated cows (experiment 1), but sensory perception was not affected in sham-operated controls. Prolactin release patterns were markedly depressed by denervation; however, oxytocin release, milk production, and calf growth rates were not affected. Although acute sham surgery attenuated weaning-induced increases in LH pulse and ovulation frequency (experiment 1), normal responses to weaning were observed in unoperated controls (experiment 2) as well as in sham-operated cows 1 yr later (experiment 3). Finally, denervated-suckled cows (n = 22) that had been denervated before conception (experiment 4) exhibited LH secretion patterns and mean postpartum intervals to luteal activity similar to those of intact- suckled cows (n = 16). In contrast, the intact-weaned group (n = 16; calves weaned at birth) responded within 2 wk postcalving with an increased frequency of LH pulses, and intervals to onset of luteal activity were shortened compared to those in the other groups. Suckling-mediated anovulation is not dependent upon mammary somatosensory cues.
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U2 - 10.1095/biolreprod49.6.1328
DO - 10.1095/biolreprod49.6.1328
M3 - Article
C2 - 8286615
AN - SCOPUS:0027385981
SN - 0006-3363
VL - 49
SP - 1328
EP - 1337
JO - Biology of reproduction
JF - Biology of reproduction
IS - 6
ER -