Regulatory changes following kainic acid-induced striatal lesions

Avian telencephalon and body weight

The neurological mechanisms associated with weight gain in animals have been extensively studied in mammals, but relatively little investigation has been carried out in birds. As in mammals, it has been shown that lesion of the ventromedial nucleus of the hypothalamus leads to hyperphagia and obesity in several species of birds. Likewise, bilateral lesions of the lateral hypothalamus result in aphagia and weight loss. Therefore, at the level of the hypothalamus, control of body weight appears to be controlled by similar neurological mechanisms in all homeothermic species via modulation of the sympathetic nervous system. Because of the role of the mammalian striatum in body weight regulation, body weight data from various manipulative studies in chickens were analyzed to see if these areas play a role in avian body weight regulation. In the first study, cycloheximide, glutamate, or saline was injected intracerebrally into 1-day-old chicks. In the second study, 3-day-old chicks received surgical ablation of the neocortex or kainic acid-induced lesions of the paleostriatum. Decreased body weight was noted in chicks that received injections of cycloheximide or glutamate, or kainic acid-induced lesions. The disruption in body weight in Experiment 1 might have been due to neurochemical pathology thought to occur in the paleostriatum. In the second experiment, lesions of the neostriatum or hyperstriatum, analogous to the neocortex in mammals, did not produce a difference in weight gain compared to controls. This preliminary work with kainic acid lesions in the chicken paleostriatum demonstrates a significant long-term decrease in body weight. As in mammals, the basal ganglia may have a role in body weight regulation.

Sex differences in regulatory changes following quinolinic acid-induced striatal lesions

The effects of sex differences and hormonal factors on the weight loss following intrastriatal injections of quinolinic acid (QA) were examined. Male, female or ovariectomized female rats were weighed each day for 30 days following bilateral injections of 150 nmol of QA or vehicle into the striatum. Although all rats injected with QA exhibited an equivalent initial loss of body weight, female lesioned rats rapidly regained weight and did not differ from controls after the first postsurgical day. On the other hand, male lesioned and female ovariectomized lesioned rats exhibited a significant but transient loss of body weight. By 19 days postsurgery all rats had recovered and exhibited comparable body weights. Histological analysis did not reveal any sex-related differences in the extent of striatal pathology following QA. These results suggest that sex and hormonal variables such as estrogen levels play an important role in the regulatory changes following excitotoxic-induced striatal damage.

Neural basis of behavior: animal models of human conditions

A variety of neurological disorders including Alzheimer's, Parkinson's, and Huntington's diseases are characterized by abnormalities within specific neuroanatomical and/or neurochemical systems. Approaches to the treatment of these and other neurological disorders are limited. The development and refinement of animal models which closely mimic human disease states would help elucidate the underlying neurobiological mechanisms of the disease as well as suggest novel therapeutic strategies for their prevention or alleviation. This symposium presents a variety of animal models that have helped us in understanding the human condition. The present introduction presents some clinically relevant findings obtained from basic experimental studies with animal models of Huntington's disease (HD) and Tourette Syndrome (TS). These studies demonstrate that animal models can provide a greater understanding of the symptomatology of disease states as well as suggest innovative new treatments.