Oxytocin and Vasopressin Neurones in Principal and Accessory Hypothalamic Magnocellular Structures Express Fos‐Immunoreactivity in Response to Acute Glucose Deprivation

Abstract

Neurohypophyseal secretion of oxytocin and vasopressin is elevated in response to decreased systemic glucose availability. In these studies, dual-label immunocytochemistry was used to identify hypothalamic neuropeptidergic magnocellular neurones that are transcriptionally activated in response to glucose substrate imbalance. Two h after i.p. injection of the glucose antimetabolite, 2-deoxy-D-glucose (2DG), or the vehicle, saline, groups of adult male rats were anaesthetized by i.p. injection with sodium pentobarbital and killed by transcardial perfusion. Sections (25 microm) through anterior and tuberal levels of the hypothalamus were processed for nuclear Fos- and cytoplasmic neuropeptide immunoreactivity (-ir). A high proportion of oxytocin-ir neurones in the supraoptic, paraventricular, and adjunct structures, including the anterior commissural, periventricular magnocellular, posterior perifornical, recurrent supraoptic, medial forebrain, and circular nuclei, were colabelled for nuclear Fos-ir following administration of 2DG. Large numbers of vasopressin neurones in the supraoptic, circular, posterior perifornical, and medial forebrain nuclei, and posterior magnocellular division and posterior subnucleus of the paraventricular nucleus were also immunostained for Fos in rats injected with the antimetabolite. These results show that decreased glucose metabolism is a stimulus for activation of the Fos stimulus-transcription cascade within oxytocin-and vasopressin-immunopositive neurones in several hypothalamic loci, findings that reflect activation of the Fos-stimulus transcription cascade within large proportions of these cell populations during this metabolic challenge. These data suggest that both peripheral hormonal and central modulatory functions of these neuropeptidergic neurones may be influenced by cellular glucose availability.

Vasopressin cell groups exhibit strongly divergent responses to copulation and male–male interactions in mice

“…In Syrian hamsters, only the SON exhibits greater activation in dominant males relative to subordinates (Kollack-Walker et al, 1997), and an extensive analysis of hypothalamic activation in mice found that no loci expressed Fos at higher levels in dominant males relative to subordinates, although dominant males did show activation of many areas above handled controls (Motta et al, 2009). Our results are likewise consistent with findings that suggest virtually all AVP cell groups of the hypothalamus, including the accessory cell groups, are responsive to metabolic challenge (Briski and Brandt, 2000). …”

Maternally involved galanin neurons in the preoptic area of the rat

“…Magnocellular neurons in the ACN have been considered as an anterior magnocellular subdivision of the paraventricular nucleus (Hou-Yu et al 1986; Nylen et al 2001). However, the ACN is often dismissed as an accessory nucleus during investigation and discussion of the oxytocin system (Briski and Brandt 2000; Knobloch and Grinevich 2014; Powers-Martin et al 2008), even though 616 oxytocin cells were counted in the ACN which is more than 50 % of the 1174 oxytocin cells of the paraventricular nucleus in the rat (Rhodes et al 1981), and the morphology as well as the oxytocin content of oxytocin neurons in the ACN were comparable to that in the PVN (Burbach et al 1987, 2006; Castel and Morris 1988). Surprisingly, even recent studies on the detailed parcellation of the paraventricular nucleus fail to mention a rostral magnocellular subdivision (Simmons and Swanson 2008).…”

N-methyl-D-aspartate receptor subunit NR2B is widely expressed throughout the rat diencephalon: An immunohistochemical study

“…Its neurons are tightly packed monopolar cells that respond to acute/chronic in vivo dehydration with intra-and intercellular changes visible at the ultrastructural level (Tweedle and Hatton, 1976), although it is still unknown whether the NC is a true osmoreceptor (Hatton, 1976). Also, many perivascu-lar nuclei, including the NC, are metabolically activated during acute glucose deprivation induced by peripheral injection of the antimetabolite 2-deoxy-D-glucose (Briski and Brandt, 2000). Given the robust NR2B-ir we find in the NC, it is likely that functional NMDA-Rs are present on NC cells and that these NMDA-Rs are involved in the responses of this nucleus to osmotic and metabolic stimuli.…”