Comparative Distribution of Vasopressin V1b and Oxytocin Receptor Messenger Ribonucleic Acids in Brain¹

Abstract

The comparative distributions of the vasopressin V1b receptor (V1bR) and the oxytocin receptor (OTR) messenger RNAs (mRNAs) are described in male rat brain using in situ hybridization histochemistry. V1bR transcripts were present in forebrain and hypothalamus and were less abundant in mid- and hindbrain regions, similar to the gradient observed with OTR transcripts. Microscopic analyses indicated that V1bR expressing cells typically demonstrated the morphology of neurons and confirmed V1bR gene expression in regions including the olfactory bulb, supraoptic, suprachiasmatic, and dorsomedial hypothalamic nuclei, piriform and entorhinal cortices, hippocampus, substantia nigra, and dorsal motor nucleus of the vagus. Most regions that expressed V1bR mRNA also expressed OTR mRNA, although OTR gene expression was much more extensive than that of the V1bR. V1bR and OTR mRNA distributions were distinct from each other and from that of the V1a receptor mRNA in brain. A few brain regions express only V1bR transcripts such as the dorsomedial hypothalamic nucleus and the external plexiform layer of the olfactory bulb. Other brain regions, such as the fields of Ammon's horn, the suprachiasmatic nucleus, the substantia nigra pars compacta, and the piriform cortex express mRNAs that encode all three receptor subtypes (V1a, V1b, and OTR), whereas brain areas including the red nucleus and supraoptic nucleus express V1bR and OTR transcripts only. These data suggest functional specialization of the V1b, OTR and V1a receptors in brain.

Amygdala–midbrain connectivity indicates a role for the mammalian parental care system in human altruism

“…Our findings are indirectly consistent with the previously postulated role for the neurotransmitters oxytocin and GABA in caregiving and costly altruism. The amygdala and PAG contain high concentrations of oxytocin [55] and oxytocinergic receptors [56,57]. Endogenous and exogenous oxytocin enhances protective behaviours in humans and other mammals [54,[58][59][60] and modulates functional connectivity specifically between the amygdala and a midbrain region proximal to the region identified here (x ¼ 25, y ¼ 225, z ¼ 218) [61].…”

Oxytocin and Rodent Models of Addiction

“…Lemaire et al (2002) proposed that the oxytocin and vasopressin V1a receptors are the predominant receptor subtypes in rat brain and spinal cord with specific distribution patterns. However, it is the vasopressin V1b2 receptor that is co-localized with oxytocin receptors in forebrain areas, with oxytocin receptor gene expression being much more robust than that of V1b2 (Vaccari, Lolait, & Ostrowski, 1998). …”

Anxiolytic- and antidepressant-like effects of the non-peptide vasopressin V 1b receptor antagonist, SSR149415, suggest an innovative approach for the treatment of stress-related disorders

“…Although it participates in the hypothalamic-pituitary-adrenal axis, regulating pituitary ACTH (corticotropin) secretion by potentiating the stimulatory effects of corticotropin releasing factor (CRF), extrahypothalamic AVP-containing neurons have been characterized in the rat, notably in the medial amygdala, that innervate limbic structures such as the lateral septum and the ventral hippocampus (1). In these latter structures, AVP was suggested to act as a neurotransmitter, exerting its action by binding to specific G protein-coupled receptors, i.e., V 1a and V 1b (2)(3)(4), which are widely distributed in the central nervous system, including the septum, cortex, and hippocampus (2,5).…”