Characteristics of prolactin binding sites in the brain of the ring dove (Streptopelia risoria)

Distribution and Characterization of Prolactin Binding Sites in the Male and Female Rat Brain: Effects of Hypophysectomy and Ovariectomy

“…A treatment with estradiol restored the PRL binding in the ovariectomized rats to above normal levels. These results of in vitro biochemical analysis together with the experimental modula tion of hormonal status provide strong preliminary evidence for the presence of PRL binding sites in rat brain.An increasing amount of data indicates that prolactin (PRL) may play a specific role in the central nervous system (CNS) at the hypothalamic level affecting dopamine neurotransmission [1,2] and also in extrahypothalamic areas [3][4][5].The localization of specific PRL binding sites within the CNS may be able to help clarify the mechanisms responsible for the autoregulation of this hormone and its effects on other as pects of CNS activities.In accordance with these observations, over the last few years we have identified and characterized using traditional in vitro competitive binding assay specific binding sites for PRL in rabbit hypothalamus and substantia nigra [6,7] and more re cently in the hypothalamus of pig, horse, pigeon and an anuran amphibian, Xenopus laevis [8.9], Other authors have also found PRL receptors in pig hypothalamus [10] as well as in the fore brain and hypothalamus of ring dove [11] and in different brain regions from the toad, Bufo arenarum [12]. Conversely at tempts to identify PRL binding sites in rat hypothalamus by in vitro competitive binding assays have so far been unsuccessful [8,13,14], Moreover in the rat in vitro autoradiographic analy sis of whole hypothalamus [14] and in vivo autoradiographic analysis of the median eminence [15,16] have generally failed to Received: December 18, 1989 Accepted after revision: June 18, 1990 demonstrate significant specific binding for PRL.…”

The Role of Prolactin in the Regulation of Clutch Size and Onset of Incubation Behavior in the American Kestrel

“…On October 9, 1998, we changed the photoperiod to 10L 14D and stepped it by 2-h intervals each week to 14L 10D. On egg-day 2, we subcutaneously implanted in the scapular region of each female (without anesthesia) an osmotic pump (model 1002: Alza Corporation, Palo Alto, CA) containing ovine (as opposed to avian) prolactin (NIDDK oPRL-21) because previous studies have shown the readily available ovine prolactin (oprolactin) to be effective in birds (Pedersen, 1989;Youngren, El Halawani, Silsby, and Phillips, 1991) and to bind specifically to crude membrane fractions of ring dove, Streptopelia risoria, brain homogenates (Buntin and Ruzycki, 1987). Each pump contained 100 l of one of three o-prolactin concentrations and pumped at a rate of 0.28 l/h.…”

Prolactin Receptors in Dove Brain: Autoradiographic Analysis of Binding Characteristics in Discrete Brain Regions and Accessibility to Blood-Borne Prolactin

“…In ring doves, intra cranial administration of ovine PRL has been shown to inhibit gonadotropin secretion [9], to facilitate food in take [10] and to stimulate parental behavior [11]. Pro lactin receptors that could conceivably mediate these changes have been detected and partially characterized in crude membrane fractions prepared from ring dove brain homogenates [12], Subsequent mapping of these receptors by in vitro autoradiography revealed a nonuniform distribution in midbrain and forebrain with highest specific binding activity in the choroid plexus, the ventromedial, suprachiasmatic, and periventricular hypothalamic nuclei, the tuberal hypothalamic region, and the preoptic area [ 13], Although species differences are apparent, a similar pattern of l25I-ovine (o) PRL binding site distribution has been reported in rabbit brain [14] and in the CNS of four songbird species [15,16] using the same in vitro autoradiographic technique. The precise distribution of CNS specific binding sites for PRL in other vertebrate species remains unknown, although PRL binding sites have been detected in brain tissue homogenates or membrane fractions prepared from several amphibian [17,18], avian [19], and mam malian [19,20] representatives.…”