Ring Doves Research Articles

Effects of Air Drying and Critical-Point Drying on Morphology of Trichomonas gallinae

Upper alimentary tract tissues of ring doves (Streptopelia risoria), experimentally infected with virulent Trichomonas gallinae, were processed for scanning electron microscopy by three procedures. Preparatory schedules which included aldehyde fixation, tannic acid, and guanidine hydrochloride fixation, as well as osmium tetroxide fixation, permitted air drying of large tissue samples from Freon?. Tissue samples prepared by this method revealed improved preservation of surface details and fewer structural artifacts when compared with tissues prepared by standard techniques and critical-point drying. Artifacts in biological tissues that have been prepared for scanning electron microscopy (SEM) may be a result of poor fixation rather than of a specific drying technique (Gamliel, 1985). In studies of megakaryocytes, human myeloblastic leukemia cells, and other soft tissues, Gamliel (1985) indicated that improved preservation of surface details and reduced swelling and shrinkage occurred when tannic acid-guanidine hydrochloride fixation and air drying from Freon? were included in tissue preparation schedules. Gamliel (1985) also indicated that comparative tissues prepared by standard techniques and criticalpoint dried appeared to be in poorer condition. A technique such as this may be beneficial in studies of trichomonad parasites (Protozoa: Sarcomastigophora). Effects of improved fixation and air drying on the morphology of Trichomonas gallinae (Rivolta, 1878) Stabler, 1938 and on avian pharyngeal epithelium were investigated. Modifications to Gamliel's (1985) basic protocol were made, and the results were compared to those obtained by standard methods. These methods were applied to other flagellated protozoa (Buchel et al., 1987; Erlandsen & Bemrick, 1987; Heath, 1981; John & Squires, 1978; Ovcinnikov et al., 1975; Warton & Honigberg, 1979). MATERIALS AND METHODS Ring doves (Streptopelia risoria) known to be specific pathogen-free were each orally intubated with 3.0 x 106 cells of virulent Trichomonas gallinae. ' I thank Dr. Harry T. Horner and Mr. Bruce Wagner, Bessey Electron Microscopy Center, for their help during technical phases of this study. This work was supported in part by a grant from the Iowa State University Graduate College. 2 Present address: Division of Mathematics and Science, Wayne State College, Wayne, Nebraska 68787, U.S.A. TRANS. AM. MICROSC. SOC., 110(2): 172-177. 1991. ? Copyright, 1991, by the American Microscopical Society, Inc. This content downloaded from 207.46.13.103 on Thu, 20 Oct 2016 04:35:14 UTC All use subject to http://about.jstor.org/terms VOL. 110, NO. 2, APRIL 1991 Prior to intubation, parasites were subcultured three times in simplified trypticase-serum (STS) medium (Difco) that had been enriched with 10% fetal bovine serum (Gibco). Birds were killed 72 h post-infection and tissue samples between 5 and 7 mm2 were excised from the pharyngeal region of each bird. Tissues from the six infected birds were processed randomly by one of the following procedures. Procedure 1. Tissue samples were fixed by immersion at 4?C for 24 h in 2% paraformaldehyde and 2.5% glutaraldehyde in 0.1 M Sorensen's dibasic sodium phosphate-monobasic potassium phosphate buffer (Lillie, 1965), pH 7.2. Following primary fixation, tissues were washed in three changes of cold buffer and then placed for 2 h in a solution of freshly filtered 2% tannic acid, 2% guanidine hydrochloride (TA-GuHCI), and buffer. Samples were washed in three changes of cold buffer, fixed in 1% osmium tetroxide (OS04), washed in three changes of cold buffer, dehydrated in ethanol, infiltrated with Freon? 113 (trichlorodifluoromethane) and exposed to air for drying. Gamliel's (1985) procedure differed from this one in that primary fixation was in 2% glutaraldehyde in Dulbecco's phosphate-buffered saline (DPBS) for 4 h or less and that all steps were performed at room temperature. Procedure 2. Tissue samples were treated similarly to those of procedure 1, except that the TA-GuHCI step was eliminated and critical-point drying replaced air drying from Freon?. Procedure 3. Tissues processed by this procedure were fixed for 6 h at 4?C by immersion in 2% paraformaldehyde and 2.5% glutaraldehyde in 0.1 M cacodylate buffer, pH 7.2. Steps following aldehyde fixation were similar to those of procedure 1, except that the TA-GuHC1 and air drying steps were eliminated, and samples were critical-point dried. All dried samples were mounted on brass specimen stubs with colloidal silver paint (Ted Pella, Inc.) and coated with approximately equal amounts of gold palladium. A JEOL JSM-35 scanning electron microscope set at 15 kV was used for all sample examinations. Photomicrographs were taken from approximately the same location on each tissue sample with Polaroid? 665 positive/negative film.

Assay validation and characterization of hepatic 5′-deiodinase activity in ring doves using reverse-T 3 as substrate

Adult ring dove hepatic 5′-deiodinase (5′D) activity was studied in vitro using reverse T 3 (rT 3) as substrate. A previous study of ring dove hepatic deiodinase in our laboratory did not include characterization studies and was unsuccessful in relating the pattern of 5′D development to that of plasma T 3. In the present study we established valid assay conditions and characterized the hepatic 5′D in doves to provide a comparison with other avian species and for future use in developmental work. Our validation studies demonstrate that 5′D activity is proportional to enzyme concentration (as postmitochondrial fraction (PMF) protein) over the range measured (0–0.163 mg PMF protein/ml, representing 0–2.19 mg original tissue/ml). Activity was linear with time from 5 to 30 min of incubation at 0.163 mg PMF protein/ml. Our 5′D assays used 20 m M DTT; activity was maximal from 5 to 30 m M DTT. Using the validated conditions the following characteristics were found: the apparent K m was 0.44 μ M rT 3, V max was 255 m M rT 3 degraded/min-mg PMF protein, and activity was completely inhibited by 1 m M PTU. Activity was maximal at pH 8.04 and at 37.5° (although this did not differ from activity at 41.5°, the body temperature of doves). In summary, this study demonstrates conditions that measure 5′D at initial velocities in dove liver and demonstrates that the hepatic 5′D enzyme in ring doves is similar to the deiodinase activity in liver of galliform birds and mammals.

The role of dicofol metabolites in the eggshell thinning response of Ring Neck Doves

Residue data is presented from shell thinning studies in Ring Neck Doves (Streptopelia risoria) fed 33 mg/kg, or 10 mg/kgp,p′ dicofol or the dicofol metabolite 1,1-bis(4-chlorophenyl)2,2 dichloroethanol (p,p′ DCD) at 10 and 32 mg/kg for approximately 90 days. The metabolism and storage of dicofol and dicofol metabolites in breeding females is examined. Concentrations ofp,p′ dicofol, DCDp,p′ dichlorobenzophenone (p,p′ DCBP),p,p′ dichlorobenzydrol (p,p′ DCBH), and 1,1-bis(4-chlorophenyl)-2,2 dichloroethylene (p,p′ DDE) were determined in liver, fat, heart, brain, oviduct and yolk of doves. The major metabolite was DCD. Doves exposed to DCD alone did not produce thinned eggshells at either dose. DCD was poorly metabolized by doves to DCBP and DCBH. DDE was present but in concentrations far below other OCs and was not a metabolite of dicofol. Doves had two metabolic routes for transforming dicofol to more water soluble metabolites, reduction to DCD and oxidation to DCBP with subsequent formation of DCBH. The formation of DCBH was limited by the rate of DCBP formation. Yolk residues of DCBP indicated individual doves varied in their ability to produce DCBP. DCBP accumulation in yolk over time was correlated with individual doves' eggshell thinning response over time of treatment. Doves with low rates of DCBP accumulation in yolk had greater declines in shell thickness per day of dicofol treatment. It is concluded that the dicofol metabolites DCD, DCBP, and DCBH are less toxic than dicofol to eggshell formation in ring neck doves.

Metabolism and storage ofp,p? dicofol in American kestrels (Falco sparverius) with comparisons to Ring Neck Doves (Streptopelia risoria)

Residues ofp,p′ dicofol,p,p′ dichlorobenzophenone (p,p′ DCBP),p,p′ dichlorobenzhydrol (p,p′ DCBH), 1,1-bis (4-chlorophenyl)-2,2-dichloroethanol (p,p′ DCD) and 1,1-bis (4-chlorophenyl)-2,2 dichloroethylene (p,p′ DDE) are reported in liver, fat, brain and oviducts of American kestrels exposed top,p′ dicofol. Breeding female kestrels were exposed to oral gavage dosages of 3.0 and 0.3 mg dicofol/kg body weight per day, equivalent to 1 or 10 mg dicofol/kg diet, for 39 days. Kestrels exhibited an eggshell thinning response similar to that produced by DDE, under these exposures. The major hepatic metabolite of dicofol in kestrels was DCD, but most organochlorine stored in tissues was in the form of dicofol. DDE was not a major metabolite of dicofol in kestrels. Compared with doves, kestrels had a significantly reduced metabolic capacity to transform dicofol to DCBP and DCBH, and had a steeper dose-response curve for dicofol-induced eggshell thinning.

Effects of brood size on inter-clutch intervals, offspring development and male-female interactions in the ring dov Streptopelia risoria

A reduction in brood size from two squabs to one reduced the inter-clutch interval of ring doves from 31 to 21 days. Development of, and parental behaviour towards, the squabs was not affected by how many there were. However, the reduction in brood size advanced behavioural interactions between males and females, with male cooing, in particular, being stimulated. Ring dove males and females have to interact behaviourally in order to stimulate ovulation. The data suggest that male courtship behaviour may influence the length of the inter-clutch intervals. Furthermore, the behavioural changes that males showed in relation to brood reduction may have contributed to the advancement of egg laying in females.

Iris Stromal Pigment Cells of the Ringed Turtle Dove

Irides from adult Ringed Turtle Doves (Streptopelia risoria) were examined using both light and electron microscopy. The anterior surface of the iris stroma contained numerous large venous sinuses overlying bright yellow pigment cells which we classified as "reflecting xanthophores." The pigment cells were filled with irregularly arranged yellow reflecting crystals and occasional pterinosome-like structures. The irides were extracted in NaOH and the extracted pigments analyzed using paper chromatography and spectrophotometry. A unique bright orange fluorescent band was found in the iris extract, but the chemical nature of the band was not determined. Although guanine was expected to be a major component of the reflecting "platelets," based on previous work with other Columbiformes, it could not be demonstrated chromatographically or spectrophotometrically.

Distribution of aromatase in the brain of the Japanese quail, ring dove, and zebra finch: An immunocytochemical study

An immunocytochemical peroxidase-antiperoxidase procedure using a purified polyclonal antibody raised against human placental aromatase was used to localize aromatase-containing cells in the brain of three avian species: the Japanese quail, the ring dove, and the zebra finch. In quail and dove, immunoreactive cells were found only in the preoptic area and hypothalamus, with a high density of positive cells being present in the medial preoptic area, in the septal area above the anterior commissure, in the ventromedial nucleus of the hypothalamus, and in rostral part of the infundibulum. Immunoreactivity was weaker in zebra finches, and no signal could therefore be detected in the ventromedial and tuberal hypothalamus. The positive material was localized in the perikarya and in adjacent cytoplasmic processes, including the full length of axons always leaving a clear unstained cell nucleus. These features could be observed in more detail on sections cut from perfused brains and stained with an alkaline phosphatase procedure. The distribution of aromatase immunoreactivity was similar in the three species although minor differences were observed in the preoptic area. The localization of labelled neurons coincided with the distribution of aromatase activity as studied by in vitro radioenzyme assays on brain nuclei dissected by the Palkovits punch method. There was one striking exception to this rule: no immunoreactivity was detected in the zebra finch telencephalon, while assays had shown the presence of an active enzyme in several nuclei such as the robustus archistriatalis, the hyperstriatum ventrale pars caudale, and the hippocampus and area parahippocampalis. The origins of this discrepancy and the functional role of the aromatase observed in the axons are discussed.

Changes in Feeding Activity, Plasma Luteinizing Hormone, and Testes Weight in Ring Doves Following Hypothalamic Injections of Prolactin

Abstract Microinjections of ovine prolactin were administered unilaterally to the ventromedial hypothalamic nucleus and the preoptic-suprachiasmatic region in adult male ring doves in an attempt to determine the site(s) at which intracranial injections of prolactin act to alter feeding behaviour and gonadotropin secretion in this species. Food intake and body weight were measured daily during a 6-day pretreatment period and the 5-day treatment period that immediately followed. During the treatment period, birds received twice daily injections (0.5 mul) of either 2.5 ng ovine prolactin or saline vehicle. An additional group of birds with cannulae in the ventromedial nucleus were given twice daily injections of 25 ng ovine prolactin. Although food consumption was unaffected by low dose prolactin treatment, birds given 25 ng prolactin injections into the ventromedial nucleus showed a significant augmentation in food intake. Injections of 25 ng prolactin into the preoptic area also increased feeding; however, the magnitude of this hyperphagic response, as expressed relative to pretreatment levels, was less than that observed following prolactin injection into the ventromedial nucleus. No differences were observed between prolactin-treated and vehicle-treated birds in either cannulation group when testes weights and plasma luteinizing hormone concentrations were compared at the end of the treatment period. However, the possibility that prolactin influenced changes in luteinizing hormone and testes weight relative to baseline values could not be assessed due to constraints imposed by the experimental paradigm used. These results suggest that prolactin-sensitive neurons in the ventromedial hypothalamic region and the preoptic area are potential sites of prolactin action in promoting hyperphagia in ring doves. However, the role of these sites in mediating prolactin-induced suppression of gonadotropin secretion in this species remains to be clarified.

The Role of Prolactin in Parental Care in a Monogamous and a Polyandrous Shorebird

The Role of Prolactin in Parental Care in a Monogamous and a Polyandrous Shorebird

Are separable aromatase systems involved in hormonal regulation of the male brain?

In vitro study of testosterone (T) metabolism shows that formation of estradiol-17 beta (E2) is regionally specific within the preoptic area (POA) of the male ring dove. The POA is known to be involved in the formation of E2 required for specific components of male sexual behavior. Two sub-areas of high aromatase activity, anterior (aPOA) and posterior preoptic (pPOA) areas, have been identified. Aromatase activity is higher in aPOA than in pPOA. The aromatase activity within the aPOA is also more sensitive to the inductive effects of low circulating T, derived from subcutaneous silastic implants, than the enzyme activity in pPOA. Kinetic analysis of preoptic fractions indicates that a similar high-affinity enzyme occurs in both areas (apparent Km less than 14 nM), but the Vmax of aPOA enzyme activity is higher than pPOA. Cells containing estrogen receptors (ER) are localized in areas of high aromatase activity. There is overlap between immunostained cells in the aPOA and in samples containing inducible aromatase activity measured in vitro. Within the aPOA there is a higher density of ER cells in the nucleus preopticus medialis. The pPOA area also contains ER, notably in the nucleus interstitialis, but at a lower density. We conclude that the hormonal regulation of the male preoptic-anterior hypothalamic region, which is a target for the behavioral action of T, involves at least two inducible aromatase systems with associated estrogen receptor cells.

Vasoactive intestinal polypeptide-like immunoreactivity during reproduction in doves: Influence of experience and number of offspring

To assess the possibility that vasoactive intestinal polypeptide (VIP) plays a role in naturally occurring changes in prolactin secretion in ring doves, we used immunohistochemical techniques to measure VIP-like immunoreactivity in the brain as a function of stage of the reproductive cycle. Differences between parental and nonparental birds in VIP profiles were detected in the ventral portion of the infundibular region. More specifically, there is an increase in cell size and staining intensity in the ventral infundibulum of breeding birds compared to simultaneously processed tissue taken from control animals. In both sexes, an increase in size of VIP-like immunoreactive cells is detectable during courtship and early incubation, anticipating the increase in plasma prolactin levels. VIP cell size remains elevated from about Incubation Day 14 to Brooding Day 14, and a steady decrease is observed during the remaining posthatching period, as squab begin to feed independently. Compared to parents rearing one squab, those with two young have a prolonged interval of increased infundibular VIP immunoreactivity. Furthermore, doves with no previous experience of a breeding cycle exhibit prolonged VIP-like immunoreactivity compared to experienced parents, paralleling previously described differences between these groups in parental behavior.

Distribution of vasoactive intestinal peptide-like and neurophysin-like immunoreactive neurons and acetylcholinesterase staining in the ring dove hypothalamus with emphasis on the question of an avian suprachiasmatic nucleus

Two nuclei, termed here the medial hypothalamic nucleus and the lateral hypothalamic retinorecipient nucleus, are possible homologs of the mammalian suprachiasmatic nucleus. As the mammalian suprachiasmatic nucleus is characterized by a dense concentration of vasoactive intestinal peptide (VIP)- and neurophysin (NP)-immunoreactive neurons and an absence of acetylcholinesterase (AChE) staining, we decided to examine these factors in the ring dove hypothalamus. Neither the medial hypothalamic nucleus nor the lateral hypothalamic retinorecipient nucleus contained either VIP- or NP-like immunoreactive neurons. The lateral hypothalamic retinorecipient nucleus stained darkly for AChE. Although there was some overlap in the distribution of VIP- and NP-like immunoreactive neurons, a clustering of both types into a well defined nucleus was not observed. Therefore, an avian homolog to the mammalian suprachiasmatic nucleus must differ in its chemoarchitecture from that of mammalian species described to date.

Vigilant Behaviour: Predictability or Randomness? Spectral Analysis of Series of Scan Durations and their Relationship with Inter‐scan Intervals

AbstractWhile feeding, many animals frequently look up and visually scan their environment. Using spectral analysis of continuous series of scan durations from a purple sandpiper Calidris maritima and Barbary doves Streptopelia risoria, we show that there are sequential non‐random patterns and significant periodicities in all the examined series such that the birds cycled regularly between short and long scans. The cycles are comparable to those for the continuous series of inter‐scan intervals of the same behavioural sequences. We suggest a re‐examination of the functional costs and benefits of instantaneous randomness versus sequential predictability in alternating between feeding and scanning and a revision of the models of the way animals alternate between these behaviour patterns.

Metallothionein production: similar responsiveness of avian liver and kidney to chronic cadmium administration

The accumulation of hepatic and renal Cd, Zn, Cu, and metallothionein (MT) was investigated in ringed turtle doves ( Streptopelia risoria) chronically exposed to 3 different concentrations of dietary Cd. When only tissue-Cd was considered as an inducer of MT, kidney was found to be 35% as responsive as liver in producing MT. However, when all potentially relevant inducing metals (Cd + Zn + Cu) were taken into account, kidney was found to be 85% as responsive as liver. The greater production of MT/mol Cd in liver was accounted for mainly by a greater co-accumulation of Zn/mol Cd in liver than in kidney. We conclude that the apparent tissue specificity in expression of MT may be overestimated by failure to consider fluctuations in multiple inducers. Variability in tissue-MT concentrations after chronic dietary Cd administration is best accounted for by a consideration of tissue-Cd, -Zn, and -Cu, rather than tissue-Cd alone.

Steroid control of sexual behavior and brain aromatase in the dove: Effects of nonaromatizable androgens, methyltrienolone (R1881), and 5α-dihydrotestosterone

This study examines the effects of nonaromatizable androgens, methyltrienolone (R1881) and 5α-dihydrotestosterone (DHT) on aggressive courtship and vocal behavior in the male ring dove. Since androgens may influence behavior by increasing the formation of estrogen in the brain, the effects of R1881 and DHT on brain aromatase activity were also studied using an in vitro microassay. Under conditions in which testosterone induced aggressive courtship patterns, the nonaromatizable androgens were ineffective. But DHT and R1881 induced vocal behavior with equal efficiency, indicating that androgens can influence mechanisms of vocal behavior without conversion to estrogens. The behavioral effectiveness of both hormones was reduced (approximately 50%) when the period between castration and treatment was doubled. Testosterone propionate increased formation of E 2 from 3H-testosterone in both the preoptic (POA) and anterior hypothalamic areas. Neither of the nonaromatizable androgens affected POA aromatase activity. The results suggest that only the aromatizable androgen, testosterone, which is also required specifically for male courtship, increases preoptic formation of estrogen.

Tests of the sequential randomness of vigilant behaviour using spectral analysis

Many animals interrupt feeding bouts in order to scan for predators; the initiation of a vigilant scan has been interpreted as a random event because the inter-scan interval (ISI) has a frequency distribution that does not differ from that produced by random models (e.g. the negative exponential distribution). This in itself, however, is a test only of instantaneous (or ‘local’) randomness and not of sequential (or ‘complete’) randomness, since it does not consider the temporal sequence of ISIs. Spectral analysis of data sets for a purple sandpiper, Calidris maritima, and Barbary doves, Streptopelia risoria, showed that, while the frequency distribution of ISIs may indicate instantaneous randomness in scanning behaviour, there are significant periodicities such that long and short ISIs cycle with a degree of predictability. Some functional costs of instantaneous randomness and benefits of sequential predictability in scanning behaviour are suggested.

Expression of biologically active recombinant-derived chicken prolactin in Escherichia coli.

The putative chicken prolactin (chPRL) cDNA clone PRL101 was manipulated in vitro and cloned into the Escherichia coli expression vector pKK2332 to produce a plasmid coding for recombinant-derived mature chPRL (R-chPRL). Expression of this manipulated cDNA sequence in E. coli resulted in the production of a 23 kDa protein which cross-reacted with specific chPRL antisera in Western blots. The partially purified protein stimulated ring dove crop sac mucosa to proliferate in a PRL bioassay, demonstrating that the R-chPRL was biologically active. R-chPRL was expressed at a level of approximately 1.5% of total cell protein.

Concentrations of plasma prolactin and luteinizing hormone following nest deprivation and renesting in ring doves ( Streptopelia risoria)

Ring doves with increased plasma prolactin and low plasma LH (Group A) or with low plasma prolactin and low plasma LH (Group B) which had been incubating sterile eggs for 12 or 18 days, respectively, had their nests and eggs removed for 3 days. Upon nest return, observations were made on the birds' readiness to renest and on changes in plasma prolactin and LH. Birds from Group A demonstrated a far greater tendency to resume incubation than birds from Group B. Nest deprivation resulted in a sharp fall in the concentration of plasma prolactin in birds which were deprived of their nests after 12 days of incubation (Group A). Following resumption of incubation no subsequent increase in the prolactin levels was observed in Group A or B. The concentration of plasma LH rose sharply after nest deprivation in both sexes of both groups and declined after return of the nests. Birds in Groups A and B which returned to their nests laid a new clutch of eggs while continuing to incubate. The total length of uninterrupted sitting following nest return was 20.9 ± 0.48 days ( n = 8). These results suggest that (1) once the mechanism responsible for the increase in plasma prolactin during incubation is disrupted, it cannot be reactivated unless the whole reproductive cycle is repeated. (2) The inhibition of LH secretion during incubation involves neural mechanisms which do not necessarily involve the anti-gonadotrophic action of prolactin.

Time course and response specificity of prolactin-induced hyperphagia in ring doves.

Intracranial injections of prolactin (PRL) have been previously shown to elevate food and water intake in ring doves. In an attempt to further characterize these PRL-induced behavioral responses and the time course of PRL action, food and/or water intake were measured as frequent intervals in male doves given a single intracerebroventricular (ICV) injection of ovine PRL (44 pmoles) or vehicle under food deprivation, water deprivation, or nondeprivation conditions. PRL increased food consumption by 35-50% over baseline levels in water deprived and nondeprived doves, although response latencies (10 hr) and durations (greater than 24 hr) were considerably longer than those reported for other orexigenic peptides. Behavioral observations of nondeprived doves further revealed that PRL significantly increased total time spent feeding and average feeding bout duration. In contrast to this pattern, water intake remained unchanged in food deprived doves and was only marginally increased in nondeprived doves following PRL treatment. Collectively, these results suggest that PRL promotes a selective and long-lasting hyperphagia which may in turn augment drinking activity.

Localization of prolactin binding sites in ring dove brain by quantitative autoradiography

Specific binding sites for prolactin have been previously detected and characterized in ring dove brain membranes. In order to map the distribution of these sites, specific binding of 125I-ovine prolactin was examined in slide-mounted sections of 6 male and 6 female ring dove brains by in vitro film autoradiography and densitometry. Analysis of 34 brain regions revealed a sex-specific pattern in specific binding activity. Although no significant sex differences were observed in any individual brain region, a trend in this direction was observed in the preoptic area. Specific binding levels in which the lower limit of the 99% confidence interval was greater than zero were detected in choroid plexus, medial habenula, lateral mesencephalic nucleus, hippocampus, parahippocampal area, preoptic area and 4 hypothalamic sites: paraventricular nucleus, ventromedial nucleus, suprachiasmatic nucleus, and tuberal region. Autoradiographic analysis of specific binding in cerebellum, ventromedial hypothalamus, and hippocampus/parahippocampus yielded relative differences that closely approximated those obtained in binding studies on tissue homogenates from these regions. These results suggest possible sites of prolactin action in altering behavioral state and neuroendocrine function in this species.