Selma Zimmerman

Effects of Cannabinoids on Sperm Morphology

Sperm morphology was studied in hybrid mice of genotype (C57BL X C3H)F1 following treatment with specific cannabinoids. Mice were treated for 5 consecutive days with the specific cannabinoid; 35 days after the last treatment, epididymal sperm were scored in the light microscope and assessed in the scanning electron microscope. The animals treated with delta9-tetrahydrocannabinol (delta9-THC) and cannabinol (CBN) had a statistically higher incidence of abnormal sperm than the controls. The incidence of abnormal sperm in the animals treated with cannabidiol (CBD) was not statistically different from the control value. The relative toxicity of the cannabinoids in these studies was delta9-THC greater than CBN greater than CBD. Normal sperm have a smooth kidney-shaped head with a prominent hook; abnormal sperm have shapes which include heads without hooks, banana-shaped heads, amorphous heads and folded heads.

Genetic Effects of Marijuana

Marijuana and its constitutive cannabinoids--tetrahydrocannabinol (THC), cannabinol (CBN), and cannabidiol (CBD)--markedly affect mammalian cells. Cytogenetic studies have revealed that cannabinoids induce chromosome aberrations in both in vivo and in vitro studies. These aberrations include chromosomal breaks, deletions, translocations, errors in chromosomal segregation, and hypoploidy, and are due to the clastogenic action of cannabinoids or to cannabinoid-induced disruption of mitotic events or both. Conflicting reports of the cytogenetic effects of cannabinoids are partially explained by the different experimental protocols, cell types, and animals used by investigators. Cannabinoids also suppress macromolecular synthesis (DNA, RNA, and protein) as well as reduce the level of histone gene expression. In general these studies show that cannabinoids are detrimental to the health of an individual.

Cannabinoids inhibit fertilization in sea urchins by reducing the fertilizing capacity of sperm

Delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) inhibit fertilization in the sea urchin Strongylocentrotus purpuratus by reducing the fertilizing capacity of the sperm. Sperm fertility depends upon their motility, and their capacity to undergo the acrosome reaction upon encountering a specific ligand derived from the eggs jelly coat. The acrosome reaction involves exocytosis of the acrosomal granule at the apex of the sperm head and elongation of the acrosomal filament. This process exposes the sperm membrane that will attach to and fuse with the egg. Pretreatment of sperm with THC prevents the triggering of the acrosome reaction by solubilized egg jelly in a dose and time dependent manner. Motility of THC-treated sperm is not reduced compared to control sperm in sea water or vehicle dissolved in sea water. The adverse effects of THC on the acrosome reaction and sperm-fertilizing capacity are reversible. Studies with ionophores suggest that THC blocks the acrosome reaction by affecting event(s) in the stimulation-secretion coupling mechanism in the sperm preceding the opening of ion channels. Ultrastructural studies show that THC, CBD and CBN block the membrane fusion reaction between the sperms plasma membrane and the acrosomal membrane that normally is elicited in response to stimulation by egg jelly to initiate the acrosome reaction. However, lipid deposits are found in the subacrosomal and centriolar fossae of cannabinoid treated sperm. The nuclear envelope is fragmented in close proximity to the lipid deposits within the subacrosomal fossa. These morphological observations suggest that cannabinoids may activate phospholipase(s) within the sperm. Biochemical studies show that THC activates phospholipase A2 activity in sperm homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

Cannabinoid Receptors in Sperm

Mammalian and invertebrate sperm contain receptors for a wide variety of neurotransmitters that regulate sperm functions required for fertilization such as motility and the initiation of the acrosome reaction. The acrosome reaction is a ligand-stimulated secretory event in sperm that enables the sperm to penetrate the egg’s investments and to fuse with the egg’s plasma membrane. Previous studies in our laboratory using [3H]CP-55,940 showed that sea urchin sperm contain cannabinoid receptors that are remarkably similar to cannabinoid receptors found in mammalian brain and peripheral organs. Cannabinoid agonists and anandamide (an endogenous ligand for cannabinoid receptors in mammalian tissues) inhibit fertilization in sea urchins by blocking the acrosome reaction. These findings, taken together with other studies showing that the gene for the human brain cannabinoid receptor also is expressed in the human testis and that anandamide is synthesized in the female reproductive tract in mammals, suggested to us that human sperm may contain cannabinoid receptors. We have obtained preliminary evidence that [3H]CP-55,940 binds to putative cannabinoid receptors in live human sperm in a saturable manner, and that cannabinoid ligands affect in vitro capacitation of human sperm. These findings show that functional cannabinoid receptors are present in sperm, suggest that sperm cannabinoid receptors and their endogenous ligands may regulate normal sperm functions required for fertilization within the female reproductive tract in humans, and also imply that smoking marijuana may affect these processes in vivo.

Chapter 23 The Mitotic Apparatus: Methods for Isolation

Publisher Summary This chapter describes the methods for isolation of the mitotic apparatus (MA). The mitotic apparatus (spindle–aster–chromosome complex) functions during cell division to bring about an equal distribution of nuclear material to the daughter cells and is responsible for initiation of cytokinesis. The rationale for the DMSO–glycerol method is to isolate functional MA with stable microtubules. As the functional activity (chromosome movement) cannot be used to assess the merits of the MA isolation method, other criteria must be employed. These involve comparisons of optical and physicochemical properties of isolated MA with MA in vivo . Using a compound microscope with bright-field optics, the MA in vivo cannot be seen and isolates are barely visible. The MA in vivo are cold-labile, pressure-labile, and colchicine-sensitive. Depending upon the method of isolation, in vitro MA also displays lability to cold, hydrostatic pressure, and sensitivity to colchicine.

THE EFFECTS OF SELECTED CHEMICAL AGENTS ON FURROW INDUCTION IN THE EGGS OF ARBACIA PUNCTULATA

Following high speed pressure-centrifugation treatment, fertilized eggs of Arbacia punctulata exhibit a furrowing reaction prior to cytokinesis. Fertilized eggs were incubated in metabolic and mitotic inhibitors and the effects of these agents on frequency, stability and position of the induced furrows were observed. Puromycin and p-fluorophenylalanine (inhibitors of protein synthesis), in concentrations which inhibit cytokinesis in control cells, did not prevent the induced furrowing reaction, although the frequency of furrow induction was reduced. Actinomycin D (an inhibitor of mRNA synthesis) had no effect on furrow induction. Heavy water and colcemid, at concentrations which block pronuclear fusion and cell division, did not block furrow induction. Mercaptoethanol treatment (at concentrations which block cytokinesis) did not reduce the frequency of induced furrows but resulted in less stable furrows and in shifting of the plane of furrow to an equatorial position. Agents that block oxidative phosphory...

The effects of hydrostatic pressure on cell membranes

Publisher Summary This chapter discusses the effects of hydrostatic pressure on cell membranes. The response of cells to high pressure is multifactorial. The cellular response to pressure is mediated through various levels of organization—biochemical, morphological, and physiological. Pressure changes at the structural and physiological levels are intimately associated. This is evident in the protozoa in which related changes occur in cell shape and movement, and in marine eggs in which changes in the structural characteristics of the cortical plasmagel are associated with alterations in cytokinetic events. Pressure-induced modifications in cell architecture quite obviously affect cell activities such as metabolism, growth, and reproduction. A cell response to pressure occurs as a direct result of pressure treatment at one level of cell organization or through association with other pressure-sensitive cellular systems. The effects of pressure on cell membranes are manifested in alterations of membrane potential, permeability, response to anesthetics, and cellular shape. It has been suggested that pressure induces conformational changes of protein and interferes with hydrophobic bonding in the membrane. The use of pressure as a research tool for studying cell membranes offers many advantages and, combined with temperature, offer the investigator new approaches for membrane analysis.