Adrenocortical responses to olfactory stimulation in rats with partial hypothalamic deafferentations and lesions.

Previous experiments from this laboratory using complete hypothalamic deafferentation have demonstrated that the adrenocortical discharge following olfactory stimulation is essentially mediated by neural pathways. In order to identify the neural afferents and the hypothalamic areas involved, this response was studied in rats with anterior (AD) and posterior (PD) partial hypothalamic deafferentations as well as in animals with bilateral lesions in the ventrolateral medial forebrain bundle (VMFB) and the gemini region (GR) in the hypothalamus. While rats with PD had a normal adrenocortical response to odor stimulation, this was completely inhibited in animals with AD and partially reduced in VMFB and GR lesioned rats. These data would indicate that the adrenocortical response following olfactory stimulation is mediated by anterior afferents to the hypothalamus and involves the VMFB and GR.