The Role of Escherichia Coli Endotoxins in The Pathogenesis of Lactation Failure in The Sow

Previous studies have implicated E. coli endotoxins in the pathogenesis of insufficient milk production in the periparturient sow. Experiment I demonstrated that E. coli endotoxins (4, 8, or 16 mg 055:B5 strain) given subcutaneously to 150-170 kg sows on day 2 postpartum (PP + 2) decreased plasma prolactin (PRL) concentrations to 25-35% of pre-endotoxin concentrations within 4 hours. Piglet weight, an indirect indicator of milk production, declined significantly concomitant with the decline in PRL. Experiment II demonstrated that 8mg endotoxin suppressed PRL and piglet growth when administered on PP + 2 but not when given on PP + 6 for the first or second time. Endotoxin administration suppressed thyrotropin releasing hormone (TRH) (100 (mu)g IV) stimulated PRL release on PP + 2 but not on PP + 6. The results suggested that the suppressive effects of E. coli endotoxins on PRL are partially mediated directly at the adenohypophysis. Experiment III demonstrated that the dopamine vesicle depleting agent, reserpine (0.025 mg/kg), and the DA receptor blocking agents, haloperidol (10 mg/sow) and chlorpromazine (0.5 mg/kg), were ineffective in elevating PRL concentrations when given on PP + 5 or PP + 6. TRH (500 (mu)g IM) elevated PRL for 20-30 minutes. These results suggested that PRL is not under chronic inhibitory control by the hypothalamus as observed in other species. Experiment IV demonstrated that PRL concentrations did not increase following electric shock stimulation or restraint and venipuncture but did decline following removal of the suckling stimulus.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Veterinary Medical Science

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Smith, Bradford Bixby

• Agriculture, Animal Pathology

Identifier

(UMI)AAI8410048

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71313