Ultrastructure of neurons of nucleus preopticus and pars lateralis of the nucleus lateralis tuberis in Gambusia (Teleosta poeciliidae)]

The nucleus preopticus (NPO) and the pars lateralis of the nucleus lateralis tuberis (NLT) have been examined at the ultrastructural level. In the NPO two types of large neurons occur, both containing 140-150 nm secretory granules. The pars lateralis of the NLT contains only one cell type with similar granules. Both of these nuclei may be the source of type A fibres innervating the gonadotropic cells of Gambusia.     

Reversible juvenile hormone inhibition of ecdysteroid and juvenile hormone synthesis by the ring gland ofDrosophila melanogaster

Juvenile hormone bisepoxide (JHB₃) and juvenile hormone III (JH III) both inhibited the in vitro production of ecdysteroids by ring glands and brain-ring gland complexes from third instar post-feeding larvae ofDrosophila melanogaster in a reversible manner, although JHB₃ had greater efficacy. The JH III and JHB₃ precursor, methyl farnesoate, did not affect ecdysteroid production. The in vitro synthesis of total detectable JH (JHB₃+JH III+methyl farnesoate) by the corpus allatum portion of the isolated ring gland was also inhibited reversibly in the presence of exogenous JHB₃ and JH III, but not by methyl farnesoate. These data indicating negative feedback are in agreement with the accepted dogma of endocrine gland regulation.     

Immunocytological localization of peptide analogs of alpha-endorphin in several neurons of the lateral nucleus tuberis of Carassius auratus L. and Cyprinus carpio L.]

Neurons of the pars lateralis of the N.L.T. of Carassius auratus and Cyprinus carpio display a positive immunocytological reaction with an anti alpha-endorphin serum. It is assumed that the peptides produced by these neurons are similar, if not identical, with alpha-endorphin, but their morphinomimetic properties have still to be established. Peptides of this kind may participate in the regulation of pituitary functions.     

Immunohistochemical detection of a substance resembling growth hormone-releasing factor in the brain of the rainbow trout (Salmo gairdneri)

Summary We studied the distribution of an immunoreactive substance resembling growth hormone-releasing factor (GRF) in the hypothalamus and pituitary gland of the rainbow trout by immunofluorescence methods. The GRF-like immunoreactive perikaryon was observed in colchicine-treated fish. The majority of GRF-containing neurons were located in the nucleus lateral tuberis; others were located in the caudal part of the preoptic nucleus of the hypothalamus. The GRF-like immunoreactive neuronal processes projected into the pars distalis via the pars nervosa of the pituitary gland. The distribution of the GRF-like immunoreactive substance in the hypothalamus and pituitary gland suggests that GRF plays a physiological role in the regulation of growth hormone release from the pituitary gland of rainbow trout, as it does in mammals.     

Juvenile hormone and reproduction in the cricket. II. Effect of rearing temperature on corpus allatum activity (in vitro) in adult females

Summary In the Mediterranean field cricket,Gryllus bimaculatus, reproduction is controlled by temperature and the corpus allatum (CA) hormone JH III. In CA of females reared at 24°12°C(168 h) (high reproduction rate) a first peak in JH III synthesis is reached about 4 days earlier than in those of 20°C females (low reproduction rate). Furthermore, in 20°C animals CA activity is low during the entire oviposition period, whereas at 24°12°C high CA activity is found during this period of adult life. The results indicate a stimulation of CA activity and reproduction by thermoperiods around a constant low temperature.Supported by the DFG (SFB 87 A 4).     

Visually guided movement in the cat: difference in the effects of a bilateral lesion of the thalamic nucleus ventralis lateralis performed either before or after training]

Bilatéral lesions of the thalamic nucleus ventralis lateralis were performed in cats, either after [1] or before [2] training to reach a moving target with the forepaw. In situation [1], lesions were ineffective; in situation [2] the animal never reached normal scores. VL thus seems to be essential only in the acquisition phase of the tested visuomotor performance.     

Neurosecretory system and storage of paraldehyde fuchsin positive neurosecretory material in the dorsal aorta in an earwig,Anisolabis annulipes Lucas (Dermaptera: Labiduridae)

Summary Each of the 2 groups of medial neurosecretory cells has 10–12 A and 2–3 B-cells. Each pars intercerebralis lateralis has 3–4 B-cells only. The 2 nervi corporis cardiaci I (NccI) join with the lateral wall of the aorta and Ncc II terminate in corpora cardiaca (Cc). Only 1 corpus allatum is present. The paraldehyde fuchsin positive neurosecretory material is stored in the dorsal aorta and not in the Cc which indicates the neurohaemal nature of the aorta.We are grateful to Prof. U.S. Srivastava for providing laboratory facilities and S.C.S.T. Uttar Pradesh for financial assistance.     

Estradiol-induced changes in TSH-like immunoreactivity of pituitary cells in female rats

Beta-thyrotropin (TSH)-producing cells in the pituitary pars distalis of female rats were studied using rabbit anti-rat beta-thyrotropin (TSH) serum and a peroxidase-antiperoxidase (PAP) immunohistochemical procedure. Animals were neonatally treated with 1 mg estradiol-dipropionate (EDP) and sacrificed at different stages of development up to adulthood. Intact females of the corresponding age served as the controls. Morphometry and stereology were used to evaluate the changes in TSH-cell number and volume densities of the cells and nuclei. All morphometric parameters examined in estradiol-treated animals showed a significant decrease in comparison with immunoreactive TSH cells of age-matched controls. The most prominent EDP-induced changes were evident in peripubertal 38-day-old rats, the number and volumetric densities of both TSH cells and their nuclei being reduced by about 90% compared to intact pituitary. This decrease in the number and volume densities of TSH cells in EDP-treated rats explicitly demonstrated that this hormone, applied neonatally, has an inhibitory effect on TSH-immunoreactive cells up to adulthood, in accordance with our earlier data obtained by light and electron microscopy.     

Photoperiodic regulation of mating behaviour in the linden bug,Pyrrhocoris apterus,is mediated by a brain inhibitory factor

Active inhibition of mating behaviour in a male insect is reported here for the first time. InPyrrhocoris apterus L. (Heteroptera), the most important inhibitory pathway runs from the pars intercerebralis (PI) of the brain and does not pass through the corpora allata. The inhibitory activity of the PI is promoted by short day conditions and suppressed by long days. As the effect of photoperiod is delayed, transfer procedures enabled us to record daily rhythms in mating behaviour during short days. While the extirpation of the PI results in a discrete phase shift of the long day rhythm, there is a much less significant phase shift after this operation during short days. Thus the PI has been shown to mediate the effect of photoperiod on both the inhibition and the rhythm of mating behaviour.     

Luteinizing hormone content of the pars tuberalis of the hypophysis of neonatally androgenized female rats

Summary The immunoreactive LH content of the pars tuberalis of neonatally androgenized female rats was studied and found to be significantly lower than that of control females at oestrus or of control males. It is concluded that the rat pars tuberalis does secrete LH and that this secretory activity is diminished by neonatal androgenization in a manner that differs from that reported for the LH secretion in the pars distalis.This investigation received financial support from Direccion de Investigacion, grants RMS-80-13 and S-80-26, Universidad Austral de Chile.     

Autoradiographic analysis of the primary visual projections of a diurnal predator (Buteo buteo L.)]

Radioautographic analysis of the optic system of a Common Buzzard (Buteo buteo L.) show hypothalamic (Meier's areas 1, 2 and 3), thalamic (nuclei lateralis anterior, geniculatus lateralis ventralis, dorsolateralis anterior), pretactal (nuclei geniculatus lateralis pretectalis--or Kuhlenbeck's geniculatus lateralis dorsalis--superficialis synencephali, griseus tectalis and area pretectalis), tegmental (nucleus ectomammillaris) and tectal visual projections. A general survey of Common Buzzard optic structures suggest a certain preponderancy of tectofugal system on thalamofugal system. Centrifugal visual system is reduced.     

Effect of amputation and limb regeneration on the pars distalis of the newt,Notophthalmus viridescens

Summary A study of the pituitary of the newt,Notophthalmus viridescens, during limb regeneration indicated no observable changes in histology or ultrastructure of any of the cells of the pars distalis when compared with the pars distalis of unamputated control newts.This investigation supported by a grant from the National Research Council of Canada to S.R. Scadding.     

Endocrine-dependent expression of circadian clock genes in insects

Current models state that insect peripheral oscillators are directly responsive to light, while mammalian peripheral clock genes are coordinated by a master clock in the brain via intermediate factors, possibly hormonal. We show that the expression levels of two circadian clock genes, period (per) and Par Domain Protein 1 (Pdp1) in the peripheral tissue of an insect model species, the linden bug Pyrrhocoris apterus, are inversely affected by contrasting photoperiods. The effect of photoperiod on per and Pdp1 mRNA levels was found to be mediated by the corpus allatum, an endocrine gland producing juvenile hormone. Our results provide the first experimental evidence for the effect of an endocrine gland on circadian clock gene expression in insects. Received 31 October 2007; received after revision 7 January 2008; accepted 9 January 2008 D. Dolezel, L. Zdechovanova: These authors contributed equally to this work.     

Immunohistochemical individualization of adenohypophyseal thyrotropic cells in the monkey Macaca irus, using a human anti-beta-TSH antibody

Using the indirect immunofluorescence technique and an antiserum against the specific beta subunit of human TSH, selective immunocytochemical staining was localized in a cell population of the pars distalis of the monkey Macaca irus. These thyrotropic cells, which were positive to aldehyde fuchsin, Alcian blue, and PAS, were localized on the one hand in the ventro-medial zone of the pars distalis, especially alongside the large vessels of this region, and on the other in the zona tuberalis, i. e. at the bottom of the pars tuberalis. Some cells, sparsely distributed, were seen in the posterior part of the lateral lobes of the pars distalis, in the vicinity of the pars intermedia. No thyrotropic cells were encountered in pars tuberalis. Pars intermedia and posterior lobe contained no cells immunoreactive to beta-hTSH. In females, the thyrotropic cells were more numerous and larger than in males. Generally the thyrotropic cells were round or oval in shape, sometimes they were polygonal.     

Age-and sex-related development of ACTH in the pars distalis and neurointermedia of rat pituitary]

The content of ACTH of the pars distalis and neurointermedia of the pituitary of adult Rats is higher in the male than in the female. This differenciation of content, according to sex, appears at puberty at the site of pars distalis; it only appears around the 60th day of life at the site of the pars intermedia. The androgens seem to be responsible for the higher percentages observed in the males.     

Immunocytological identification of two cell types in the intermediate lobe of the hypophysis of salmonids: presence of ACTH and alpha-MSH]

The lead-haematoxylin positive cells (PbH+) of the rostral pars distalis react with antibodies anti-1-24 ACTH and anti-17-39 ACTH; the pars intermedia (PI) is composed of two cell categories, but only one is revealed with cyto-immunological techniques and contains ACTH and alpha-MSH in several Salmonid species.     

Cytoimmunological study of the corticotrophic and corticomelanotrophic cells in the adenohypophysis of Boops salpa L. (marine teleost) in different experimental conditions (variation of salinity and of background color)]

The cytoimmunological study of the adenohypophysis of Boops salpa (marine Teleost), in different experimental conditions confirmed that the MacConaill's hematoxyline-positive cells contain: 1. ACTH (Corticotrophic Hormone) in the pars distalis, 2. MSH (Melanocyte-Stimulating Hormone) and ACTH in the pars intermedia.     

The nucleus lateralis tuberis in the fresh water teleost,Clarias batrachus linn

Zusammenfassung Nachweis, dass die Aktivität der Zellen des Nucleus lateralis bei Fischen, während der Ruhe- und Laichzeit untersucht, eine zyklische ist. Starke Granulation im Nucleus lateralis und Nucleus praeopticus wurde bei einem 21 Tage alten, kastrierten Fisch beobachtet: Granulationsschwund nach Injektion von Testosteronpropionat und Östradiol-dipropionat (Gesamtdosis 5 mg).

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The investigation was supported by a grant from the Ford Foundation, New-Delhi.     

Antidiuretic hormone involvement in the release of α-melanocyte-stimulating hormone by hyperosmotic stimuli

Summary In the normal Wistar rat, the plasma -MSH level was raised by hypertonic saline injection (as compared with control rats injected with isotonic saline). No such rise in -MSH followed hypertonic saline administration in the Brattleboro (hereditary diabetes insipidus) animal (compared to isotonic saline injected controls). It is suggested that, in the rat, endogenous antidiuretic hormone is involved in the secretory response of the pars intermedia to osmotic stimuli.     

Immunohistochemical detection of a substance resembling growth hormone-releasing factor in the brain of the rainbow trout (Salmo gairdneri)

We studied the distribution of an immunoreactive substance resembling growth hormone-releasing factor (GRF) in the hypothalamus and pituitary gland of the rainbow trout by immunofluorescence methods. The GRF-like immunoreactive perikaryon was observed in colchicine-treated fish. The majority of GRF-containing neurons were located in the nucleus lateral tuberis; others were located in the caudal part of the preoptic nucleus of the hypothalamus. The GRF-like immunoreactive neuronal processes projected into the pars distalis via the pars nervosa of the pituitary gland. The distribution of the GRF-like immunoreactive substance in the hypothalamus and pituitary gland suggests that GRF plays a physiological role in the regulation of growth hormone release from the pituitary gland of rainbow trout, as it does in mammals.