Developmental toxicity of levo-alpha-acetylmethadol (LAAM) in tolerant rats

Caring for pregnant opioid abusers in Vermont: A potential model for non-urban areas

Opioid addiction is no longer a primarily urban problem. As dependence on heroin and prescription pain relievers has become a significant issue in rural areas, the need for effective treatment of opioid-dependent pregnant women and their neonates has grown accordingly. In addition to the adverse perinatal outcomes associated with opioid addiction in pregnant women, the high costs of caring for these mothers and their babies motivate efforts to develop appropriate treatment models. We found that integration and coordination of services that promote maternal recovery and ability to parent are key requirements for treatment of opioid dependence during pregnancy. Unfortunately, lack of experience and resources makes such coordination a real challenge in rural areas. In this review, we discuss how we managed the challenges of developing a comprehensive program for treatment of opioid dependence during pregnancy. In addition, we outline our approach for facilitating the development of community-based programs to help these patients and families in rural regions of Vermont. Close relationships between our tertiary care center, local hospitals, community health care infrastructure, and legislators bolstered our efforts. In particular, appreciation for the severity and importance of the opioid-dependence problem in Vermont among health care providers and state legislators was paramount for our success in developing a state-wide treatment program. This approach can inform similar efforts in other rural regions of the United States, and has great potential to improve both access and quality of care for women struggling with opioid dependence.

Prenatal opiate exposure impairs radial arm maze performance and reduces levels of BDNF precursor following training

Prenatal exposure to opiates, which is invariably followed by postnatal withdrawal, can affect cognitive performance. To further characterize these effects, we examined radial 8-arm maze performance and expression of brain derived neurotrophic factor (BDNF) in male rats prenatally exposed to the opiate l-alpha-acetylmethadol (LAAM). Female rats received 1.0 mg/kg/day LAAM or water via daily oral gavage for 28 days prior to breeding, during breeding, and throughout pregnancy. Pups were fostered to non-treated lactating dams at birth and underwent neonatal opiate withdrawal. At 5-6 months, prenatal water- and LAAM-exposed males (n=6 each; non-littermates) received radial arm maze training consisting of ten trials a day for five days and three retention trials on day six. Rats prenatally exposed to LAAM had poorer maze performance, decreased percent correct responding and more reference and working memory errors than prenatal water-treated controls. However, they were able to acquire the task by the end of training. There were no differences between the groups on retention 24 h after testing. Following retention testing, hippocampi were removed and protein extracted from cytosol and synaptic fractions. Western blots were used to measure levels of mature and precursor BDNF protein, as well as the BDNF receptor TrkB. BDNF precursor protein was significantly decreased in the synaptic fraction of trained prenatal LAAM-treated rats compared to prenatal water-treated trained controls. No effects were found for the full-length or truncated TrkB receptor. In untrained rats, prenatal treatment did not affect any of the measures. These data suggest that prenatal opiate exposure and/or postnatal withdrawal compromise expression of proteins involved in the neural plasticity underlying learning.

Prenatal opiate exposure attenuates LPS-induced fever in adult rats: role of interleukin-1beta

Much is known about the immunomodulatory effects of opiate exposure and withdrawal in adult rats. However, little research has delved into understanding the immunological consequences of prenatal opiate exposure and postnatal withdrawal. The purpose of the current study was to measure changes in responding to immune stimulation in adult rats following prenatal opiate exposure. Further, we sought to characterize the role of interleukin (IL)-1beta in these changes. Following prenatal exposure to the long-acting opiate l-alpha-acetylmethadol (LAAM), adult male and female rats were assessed for their fever response to lipopolysaccharide (LPS). Blood and tissue samples were collected to measure circulating IL-1beta and IL-1beta protein in the hypothalamus and spleen. Prenatal LAAM exposure resulted in a blunted fever response to LPS injection without any changes in basal body temperature or in response to saline injection. Circulating IL-1beta was not affected by prenatal LAAM exposure, nor was IL-1beta protein in the spleen. Interestingly, mature IL-1beta protein was elevated in the hypothalamus of prenatally LAAM-treated rats. These results indicate that prenatal opiate exposure blunts the fever response of adult offspring. Direct action of IL-1beta is likely not the cause of the dysfunction reported here. However, alterations in signaling mechanisms downstream from IL-1beta may play a role in the altered fever response in adult rats treated prenatally with opiates.

HPA axis dysregulation following prenatal opiate exposure and postnatal withdrawal

We examined the effects of prenatal exposure to the long acting opiate l-alpha-acetylmethadol (LAAM) followed by postnatal withdrawal on hypothalamic-pituitary-adrenal (HPA) axis reactivity in neonatal and adult rats and anxiety-like behavior in adult rats. Female rats were treated with LAAM (0, 0.2, or 1.0 mg/kg/day) via oral gavage for 28 days prior to and continuing throughout pregnancy. Pups were fostered at birth to nontreated, lactating dams and underwent opiate withdrawal. On postnatal day (PND) 18, prenatal opiate-exposed male and female rat pups displayed a decreased corticosterone response 2 h after the application of an immunological stressor and 15 min following a social stressor compared to controls. In contrast, in adulthood, prenatal opiate-treated rats showed a heightened corticosterone response compared to prenatal water-treated controls at 3 h, but not 8 h, following an immunological stressor. Males prenatally treated with 1.0 mg/kg LAAM displayed elevated startle responding compared to the other prenatally treated male groups, but there was no effect of prenatal treatment in females. There were no effects of prenatal treatment in the open field test in either sex. These results suggest that prenatal opiate exposure followed by postnatal withdrawal dysregulated the HPA axis response to stressors in the neonate and adult and differentially affected adult anxiety-like behavior in males and females.