Changes in multiunit activity and EEG induced by the administration of natural progestins to flaxedil immobilized cats

Kubli‐Garfias, Carlos; Cervantes, Miguel; Beyer, Carlos

doi:10.1016/0006-8993(76)91008-8

Cited by 39 publications

(5 citation statements)

References 16 publications

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“…Although some progestins can decrease neuronal ex citability either directly -by acting on the membrane (membrane stabilization) [27][28][29][30][31] -or indirectly -by en hancing the effect of GABA on the GABA-A receptor [32][33][34], by enhancing adenosine actions [35] or by de creasing the response to excitatory amino acids [36] these effects are too rapid and short lasting to explain Pinduced SI. Therefore, the long latency with which pro gestins induce SI suggests the participation of protein synthesis.…”

Section: Discussionmentioning

confidence: 99%

Progesterone, but Not LHRH or Prostaglandin E<sub>2</sub>, Induces Sequential Inhibition of Lordosis to Various Lordogenic Agents

González‐Mariscal

Melo²,

Beyer³

1993

Neuroendocrinology

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In experiment I we studied the capacity of progesterone (P) and two nonsteroidal agents that activate lordosis, but do not bind to the progestin receptor (PR), i.e. luteinizing hormone-releasing hormone (LHRH) and prostaglandin E₂ (PGE₂) to induce sequential inhibition (SI) in ovariectomized estradiol-primed rats. The administration of 1 mg P, 5 µg LHRH or 100 µg PGE₂ induced significant lordosis within 4 h. An injection of 1 mg P, 24 h after the administration of the above lordogenic agents, induced significant lordosis in rats pretreated with LHRH or PGE₂, but not in those pretreated with P. Thus, only P induced SI (p < 0.025). In experiment II we investigated if progestin-induced SI results in a reduced capacity of the subjects to respond only to P or to other lordogenic agents. The synthetic progestin norgestrel (400 µg administered 24 h earlier) significantly reduced the responsiveness to P (p < 0.01), LHRH (p < 0.01), PGE₂ (p < 0.025) and dibutyryl cyclic AMP (db cAMP p < 0.01). Results suggest that SI is triggered only by agents that bind to the PR (experiment I) and that it decreases the responsiveness of rats not only to P but also to other lordogenic agents (experiment II).

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Section: Discussionmentioning

confidence: 99%

Progesterone, but Not LHRH or Prostaglandin E<sub>2</sub>, Induces Sequential Inhibition of Lordosis to Various Lordogenic Agents

González‐Mariscal

Melo²,

Beyer³

1993

Neuroendocrinology

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“…One is that P acts via a direct membrane effect to alter nerve cell membrane stability and affect firing rate (Beyer, Larsson, & Cruz, 1979). The anesthetic properties exhibited by certain progestins is evidence in support of this hypothesis (Kubli-Garfias, Cervantes, & Beyer, 1976;Meyerson, 1967). A second hypothesis suggests that P action is mediated through a second messenger cyclic nucleotide cascade (Beyer, Canchola, & Larsson, 1981).…”

Section: Discussionmentioning

confidence: 94%

Temporal aspects of ventromedial hypothalamic progesterone action in the facilitation of estrous behavior in the female rat.

Glaser¹,

Etgen²,

Barfield³

1987

Behavioral Neuroscience

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Progesterone (P) action following estrogen priming is required normally for the facilitation of estrous behavior in female rats. Although mechanisms by which P exerts its influence on estrous responsiveness have not been elucidated, the primary site of action of P has been shown to be the ventromedial nucleus of the hypothalamus (VMN). The objective of the present series of experiments was to describe the temporal parameters of P action in the VMN in the facilitation of estrous behavior in estrogen-primed female rats. Subjects were female Long-Evans rats stereotaxically outfitted with 23-ga. guide cannulae directed towards the VMN. Crystalline P was applied directly to the brain tissue via bilateral 28-ga. insert cannulae, which could be inserted and removed easily through the guide cannulae. Animals were ovariectomized and estrogen primed with 5% estradiol Silastic capsules. They received a counterbalanced series of two experimental tests: one involving a manipulation with a P-filled implant, and another with a blank implant. In the first experiment, a significant increase in estrous responsiveness occurred only after 2 hr exposure of the VMN to P, whereas 4 hr were required for a full display of estrous behavior, including solicitation. In Experiment 2, P was lowered into the brain for either 1, 2, or 4 hr, and testing took place 4 hr after the lowering of the implant. It was found that 2 hr of P exposure was sufficient to facilitate full estrous responsiveness at 4 hr. In Experiment 3, it was revealed that the duration of estrous responsiveness was directly related to the time the P implant remained in the brain. In the fourth experiment, the time course of P retention in brain tissue, revealed by determination of 3H-progesterone levels in hypothalamus, agreed with the behavioral findings. Progesterone levels in the region of the VMN remained high while a P implant was in place, but declined rapidly after removal. A dual mechanistic hypothesis for P action in the facilitation of estrous behavior is presented.

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“…The overall secretory products of male or female special zone tissue are known to be C19 and C21, 5a-and 5P-reduced steroids (Weiss and Ford, 1982;Weiss, 1984;Weiss and Carson, 1987). These unique steroids are known to modulate brain function and to inhibit uterine contraction in eutherian species (Kubli-Garfias et al, 1976, 1979, 1980. Since these reduced steroid products are found in high concentrations in the adrenal venous blood of female possums (Edgar et al, 19891, it seems likely that there are extra-adrenal target tissues capable of responding to these steroids.…”

Section: Special Zone In Males and Its Relationship To Femalesmentioning

confidence: 99%

Spontaneous or experimentally induced formation of a special zone in the adrenal cortex of the adult brush‐tailed possum (trichosurus vulpecula)

Kerr¹,

Weiss²

1991

Am. J. Anat.

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The cytology and ultrastructure of the hypertrophied special zone, which is formed spontaneously in the adrenal cortex of adult female brush-tailed possums (Trichosurus vulpecula), was compared to the adrenocortical tissue in adult males in which the special zone, normally absent, was induced following castration alone or by additional treatment with follicle-stimulating hormone (FSH). The special zone in females was situated between the zona fasciculata and the zona reticularis, the latter being a rudimentary zone in this species. Special zone tissue extended as a broad band parallel to and on one side of the adrenal medulla. In the luteal phase of the reproductive cycle, the special zone cells showed ultrastructural features commonly associated with steroidogenic tissues, with many mitochondria and compact masses of smooth endoplasmic reticulum. Cytoplasmic lipid inclusions were rarely observed. In lactating females, however, the special zone cells exhibited cytological and ultrastructural features suggestive of a transformation in their morphology broadly divided into two types of cells: (1) cells at the periphery of the special zone (closest to the zona fasciculata) showed variable quantities of lipid inclusions, mitochondria with dispersed cristae, and segregation of the smooth endoplasmic reticulum into compact masses; (2) cells within the more central regions showed an increasing abundance of lipid inclusions which in many cells became the dominant feature of the cytoplasm. These special zone cells contained very little smooth endoplasmic reticulum and their mitochondria contained few cristae together with amorphous granular material within the matrix. In castrated males, special zone tissue developed between the zona fasciculata and the zona reticularis, appearing initially as focal islands of cells (8 months postcastration) and later (11 months postcastration) expanding into a single zone, probably via the proliferation and differentiation of adjacent cells of the zona fasciculata and longitudinal growth of the special zone. Similar focal aggregations of special zone cells were induced after 14 days of FSH treatment given to 2-month castrated males. In all castrated and FSH-treated castrated males, the ultrastructure of special zone cells was similar to that of special zone cells in luteal-phase female possums. The findings suggest that the formation and cellular composition of the special zone is associated with changes in the pituitary-gonadal axis and that FSH plays a primary role in the differentiation of this tissue.

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Changes in multiunit activity and EEG induced by the administration of natural progestins to flaxedil immobilized cats

Cited by 39 publications

References 16 publications

Progesterone, but Not LHRH or Prostaglandin E<sub>2</sub>, Induces Sequential Inhibition of Lordosis to Various Lordogenic Agents

Progesterone, but Not LHRH or Prostaglandin E<sub>2</sub>, Induces Sequential Inhibition of Lordosis to Various Lordogenic Agents

Temporal aspects of ventromedial hypothalamic progesterone action in the facilitation of estrous behavior in the female rat.

Spontaneous or experimentally induced formation of a special zone in the adrenal cortex of the adult brush‐tailed possum (trichosurus vulpecula)

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