Pharmacological characteristics and anatomical distribution of [3H]oxytocin-binding sites in the wistar rat brain studied by autoradiography

Neurophysins, rather than Receptors, are Involved in [3H]Oxytocin and [3H]Vasopressin Binding Detected by Autoradiography in the Hypothalamo‐Neurohypophyseal System

“…This possibility has already been proposed to explain intense binding of VP in the pituitary (21,24). In a previous study, we detected [3H]OT binding in the magnocellular nuclei of Long Evans rats (1 1) but not of Wistar rats, which contain less neurohypophyseal hormones and secretory vesicles than the Long Evans strain (9). However, as already pointed out ( I 9, 20), the interaction characteristics of the neurohypophyseal peptides with neurophysins, such as a K, above the micromolar range and optimal binding around pH 5.5 (26,27), should not permit tritiated peptides to bind to the neurophysins under the conditions used in autoradiographic studies (tritiated peptide concentrations in the nanomolar range, pH 7.4).…”

“…Specific neurohypophyseal hormone-binding sites have been characterized and localized in the brain using binding techniques to acellular preparations (for examples see 1-6) and/or autoradiography (for examples see [7][8][9][10][11][12][13][14]. Two types of binding sites have thus been clearly defined, oxytocin (0T)-binding sites, which havc nanomolar-range affinity for O T and vasopressin (VP), and VP-binding sites, which have nanomolar-range affinity for VP and a much lower affinity for OT (3,11).…”

“…In the rat brain, the two types of sites have quite distinct distributions: OT-binding sites occur mainly in the ventral subiculum, several nuclei of the amygdala, the ventromedial hypothalamic nucleus, the bed nucleus of the stria terminalis and the olfactory tubercle (8-11, 13, 14); VP-binding sites are mainly detected in the nucleus of the solitary tract, several thalamic nuclei, the suprachiasmatic nucleus, the fundus striati and the lateral septa1 nucleus (7, 8, 10-13). The pharmacological characteristics (high affinity, low capacity, saturability) of the OT and VP sites detected in such locations (l-6), and their occurrence in areas where exogenous O T or VP can affect the electrical response of neurons (1 [5][6][7][8][9][10][11][12][13][14][15][16][17], suggest that they are functional receptors.…”

Chronic gestational cocaine treatment decreases oxytocin levels in the medial preoptic area, ventral tegmental area and hippocampus in Sprague-Dawley rats

“…28 Receptors that bind oxytocin, dopamine or cocaine are found in several brain structures of the limbic system including the VTA, HIP and AMY. 20,[28][29][30][31] Cocaine, a dopaminergic (as well as serotonergic and noradrenergic) reuptake inhibitor, may alter oxytocin levels indirectly via its actions on the dopaminergic system in the VTA 32,33 Manipulations of the dopaminergic system have been reported to alter some of the same behaviors that are altered by both cocaine and oxytocin. 34,35 However, since gestational cocaine treatment alters maternal behavior and only slightly increases locomotor and stereotyped behaviors, the dopaminergic system is probably not the only neurotransmitter system implicated in the effects of cocaine on maternal behavior.…”

Oxytocin in the Bed Nucleus of the Stria Terminalis and Lateral Septum Facilitates Bursting of Hypothalamic Oxytocin Neurons in Suckled Rats

“…The presence of specific OT-binding sites particularly within the limbic system (central amygdaloid nucleus, lateral septum and contains a high density of OT-binding sites (13)(14)(15). The increase in this OT-binding capacity during lactation (1 5) and the increase in noradrenergic metabolism within the BST during suckling (17) implicates this area in the response of the CNS to suckling.…”