Anaesthetic problems.

Gonadotropin-releasing hormone (GnRH) and oxytocin both stimulate the secretion of luteinizing hormone (LH), although with different characteristics. Therefore, interaction between oxytocin and GnRH in the control of LH may be postulated. We developed models for investigating whether oxytocin can modulate GnRH action on LH in vivo. Pentobarbitone is known to pharmacologically isolate the pituitary from hypothalamic GnRH. We found that after pentobarbitone anesthesia of female rats at proestrus, oxytocin caused a synergistically enhanced LH response to administered GnRH (p < 0.04). In a second series of experiments, female proestrous rats were anesthetized with althesin. This anesthetic allows transport of endogenous GnRH from the hypothalamus to the pituitary. In control animals, which received no exogenous hormone, there was a surge in the mean LH concentration on the evening of proestrus, indicating the presence of endogenous GnRH activity. Thus, the novel model enables detection of interactions of administered hormones with endogenous GnRH. Administration of GnRH plus oxytocin in the afternoon of proestrus caused a reduction (p < 0.01) in the mean level of LH observed in the evening. The reduction was larger than if GnRH alone was administered. Following althesin anesthesia, rats sometimes had low LH levels on the afternoon of proestrus. There was a statistically significant difference between the number of rats that received oxytocin plus GnRH and had low LH levels and the number with low LH levels in the control group (p < 0.02). Neither of the hormones administered alone had a significant effect. Thus, it appears that oxytocin accentuated the effect of GnRH in reducing LH concentrations in althesin-anesthetized rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Alfaxalone Alfadolone Mixture↗

PubMed1995

Development of a swine animal model for the study of sudden infant death syndrome.

An animal model with selective cardiac autonomic denervation was developed in neonatal swine for the purpose of future studies concerning the possible role of abnormal cardiac innervation in the etiology of sudden infant death syndrome. Twenty-six 4- to 8-day old piglets were randomly assigned to one of the following treatment groups: right stellate ganglionectomy (RSG), left stellate ganglionectomy (LSG), right cardiac vagotomy (RCV), and sham-operated control group. Piglets were anesthetized with Saffan and mechanically ventilated on room air. The thoracic wall was opened, and the sternum was divided, permitting exposure of pleura, heart, and lungs. After completion of one of these operative procedures, the thoracic wall was closed in layers. On successful recovery from anesthesia and extubation, piglets were returned to their sows. Postoperative administration of antibiotics was performed during the first week. Electrocardiograms were recorded once a week over an 8-week period. The sham-operated control group had a postnatal increase in QTc and decrease in heart rate. The RSG group had significantly longer QTc than the sham-operated control group QTc, whereas the RCV group had significantly shorter QTc interval than sham-operated controls. Surgical complications caused the death of two piglets (hemorrhage in one and aspiration in the other), infection caused the death of one piglet 2 weeks after surgery, and three died of unknown causes (one from the RSG group and two from the RCV group). The cause of death for these three animals could not be determined (necropsy was not revealing) because they were not monitored at the time of their demise.(ABSTRACT TRUNCATED AT 250 WORDS)

Alfaxalone Alfadolone Mixture↗