Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Veterinary Anatomy

First Advisor

Carol D. Jacobson


All mammalian neonates are equipped with behavioral and physiological strategies to maintain homeostasis. The central nervous system (CNS) controls most aspects of homeostasis in the adult mammal, and presumably in the neonate as well, but the anatomical and physiological pathways involved may differ considerably between neonates and adults. Neurogenesis is considered a prenatal process in most mammals. However, in the Brazilian opossum, Monodelphis domestica, neurons are still being produced in the forebrain after birth. Therefore, Brazilian opossum newborns cannot regulate homeostasis at the forebrain level, although, in the adult, the forebrain consists of control centers for food intake and water balance. The Brazilian opossum provides an excellent mammalian model to study CNS adaptations for neonatal existence. In addition, the comparison of Eutherian and Metatherian brain systems can provide information on conserved pathways, and those that are specific for Metatherian survival;Because the forebrain of the Brazilian opossum is still forming at birth, we predict that hindbrain nuclei may be involved in the regulation of nutrient and fluid intake. Cholecystokinin (CCK) is involved in the regulation of food intake. Arginine vasopressin (AVP) plays a major role in fluid regulation. The purpose of the studies described in this dissertation was to focus on the expression of cholecystokinin and vasopressin binding sites in the neonatal Metatherian and Eutherian brain, with attention being paid to those brainstem nuclei that could potentially be involved in the regulation of nutrient or fluid intake;We found that both CCK and AVP binding sites are expressed transiently in the facial motor nucleus (FMN) of the neonatal rat, and CCK binding sites are expressed transiently in the FMN of the neonatal Brazilian opossum as well. As the FMN controls facial musculature, it is intimately involved in fluid and nutrient intake behavior in neonates. The transient expression of binding sites in this region suggests that cholecystokinin may be regulating nutrient intake at the brainstem level in mammalian neonates. The transient expression of vasopressin binding sites only in the neonatal rat facial may indicate that the regulation of water balance in neonates is controlled by different pathways in these two species.



Digital Repository @ Iowa State University,

Copyright Owner

Mary Cathleen Kuehl-Kovarik



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160 pages